Recent measurements in hadron-hadron collisions at RHIC and LHC involving heavy quarks will be presented. The results are related to the production of c and b quarks and the study of quarkonium. Also measurements involving the search and study of exotic final states, such as tetraquark and pentaquark candidates, are presented and discussed.
Recent highlights from experiments involving target and/or beam polarization at BNL, CERN, DESY, Fermilab, and Jefferson Lab are presented. These measurements aim at unraveling proton spin in terms of the contributions from its quarks and gluons; how proton spin is correlated with parton motion inside the proton; and how the proton spin influences the spatial distributions of partons, thus...
I will discuss recent progress in the theoretical and phenomenological investigation of the spin structure of the nucleon. In particular, I will report on the status of the verification of the spin sum rule for the proton. I will focus on the possibility to access information on the quark orbital angular momentum from different types of parton distributions, such as transverse momentum...
An impressive amount of data from the Large Hadron Collider (LHC) is allowing searches for physics beyond the Standard Model with remarkable reach. Uncovering the mysteries potentially hiding in this data requires a precision understanding of Quantum Chromodynamics (QCD) both for signal and background processes. In this talk I review recent theoretical progress in our ability to understand...
Ultraperipheral collisions at the LHC and RHIC offer the highest currently available energy for photon-nucleon and photon-nucleus collisions. Thus they are a valuable tool for studying the gluonic structure of hadrons and nuclei at small x. This talk will discuss experimental results in ultraperipheral collisions, most prominently exclusive vector meson production. We will also discuss recent...
We report on the first simultaneous extraction of unpolarized parton distributions and fragmentation functions from a global QCD Monte Carlo analysis of inclusive and semi-inclusive deep-inelastic scattering, Drell-Yan lepton-pair production, and single-inclusive e+e- annihilation data. We use data resampling techniques to thoroughly explore the Bayesian posterior distribution of the...
With the pp collision dataset collected at 13 TeV, detailed measurements of Higgs boson properties can be performed. This talk presents measurements of Higgs boson properties using Higgs boson decays to two photons, two Z bosons, and two W bosons, including production mode cross sections and simplified template cross sections.
In this talk LUXE (Laser Und XFEL Experiment) is discussed. It is an experiment that aims to use the high-quality and high-energy electron beam of the European XFEL and a powerful laser. The scientific objective of the experiment is to study quantum electrodynamics processes in the regime of strong fields. High-energy electrons, accelerated by the European XFEL linear accelerator, and...
We report an update of the ABM PDF fit with a focus on the impact of recent data from the LHC, in particular the ones on W- and Z-boson and not-resonant lepton pair production. Different
approaches to generation of the nucleon photon distribution are considered within the ABM framework and compared to the relevant data. The updated values of strong coupling constant and the heavy quark...
Observables sensitive to saturation in DIS will be reviewed. Particular triggers on final state particles in DIS make unitarity limits and saturation prominent. Perhaps surprisingly, it appears that one can even trigger on events where unitarity limits are visible for quark-antiquark dipoles, due to gluon saturation, but where quark occupancies are below saturation.
The Pierre Auger Observatory is the world's largest detector for the observation of ultra high energy cosmic rays (UHECRs). We use a series of fluorescence telescopes and a particle array at the surface to obtain detailed measurements of the energy spectrum, mass composition and arrival directions of primary cosmic rays with energies above 10^17 eV with accuracy not attainable until now. ...
We present recent results on the analysis of Higgs to WW decays and the corresponding constraints on the Higgs couplings. Focus is concentrated on the recent differential analysis of the Higgs boson transverse momentum and associated production of hadronic jets exploiting the full Run 2 statistics. Recent constraints on new physics models derived from high mass searches in the WW channel are...
The LHCb collaboration has measured cross sections for production of two charmed-particles in pp collisions. These include opposite-sign and same-sign open-charm pair production where the former is dominantly produced in a single parton scattering (SPS) but the latter can be used to study double parton scattering (DPS). In this work we have set up a NLO pQCD framework to calculate double...
The final CT18 global analysis released at the end of 2019 is based on the most complete combination of LHC and non-LHC experimental measurements to date. We discuss implications of this expansive data set for the understanding of the unpolarized PDFs and introduce several alternative fits to explore a number of critical features: the PDF pulls of the high-precision ATLAS 7 TeV W/Z data...
We present a new approach to performing Bayesian inference for QCD analysis of nucleon structure and hadronization, using machine learning to construct the inverse function mapping quantum correlation functions to observables. The new concept provides an alternative paradigm to the standard maximum likelihood or Bayesian posterior sampling methods. The effectiveness of the new technology is...
I will present the most recent developments on the reformulation of small x physics in terms of TMD distributions, and how it allows to study spin physics without going beyond the eikonal approximation.
The measurement of Higgs boson production in association with a ttbar pair is essential to understand the top-quark couplings to the Higgs boson. This talk presents the analyses using Higgs boson decays to bbbar pairs, to two Z bosons, to other multi-lepton final states, and to a pair of photons, using pp collision data collected at 13 TeV.
SoLID spectrometer was proposed to fully exploit the potential of JLab 12 GeV energy upgrade. It is a large acceptance detector which can handle very high luminosity. An overview of the exciting rich physics program will be given, which includes a number of planned measurements: a multi-dimensional mapping of semi-inclusive DIS asymmetries to reach ultimate precision for tomography of the...
Measurements of W/Z-boson production in association with jets provide important tests of perturbative QCD prediction and also yield information about the parton distribution functions of the proton. First, differential cross-sections for Z-boson production in association with jets using proton-proton collisions collected by the ATLAS experiment at √s = 8 TeV are presented. The data are...
We present a constrained analysis of the valence transversity Parton Distribution Functions from dihadron production in semi-inclusive DIS. While usual extractions of the transversity distributions rely explicitly on the fulfilment of the Soffer bounds, our analysis releases that implicit restriction to implement further explicit constraints through the Lagrange multipliers method. The results...
Color charge correlations in the proton at moderately small $x \sim 0.1$
are extracted from its light-cone wave function. The charge
fluctuations are far from Gaussian. Correlators are described by
n-body GPDs which exhibit interesting dependence on impact parameter
as well as on the relative transverse momentum (or distance) of the
gluon probes.
Furthermore, this analysis provides...
I will give an update on the latest major PDF update with the MSTW/MMHT
framework. The update includes the effects of numerous new data sets, mainly
from the LHC. This includes vector boson production, differential in rapidity,
mass or p_T, or usually some combination. We also include new jet data and
inclusive and differential top pair producation data. There have also been...
Precise measurements of the Higgs boson Yukawa couplings are important tests of the Standard Model of particle physics. In this talk, the most recent results of the analyses performed by the CMS experiment studying Higgs boson decays to fermions will be presented.
Measurements of electroweak bosons produced in Pb+Pb collisions as well as photon and jet production in small collision systems are of great interest to understanding the partonic structure of heavy nuclei, and serve as a constraint on the initial state in large collision systems. These channels are sensitive to a broad set of physics effects such as the modification of the parton densities in...
Recently, a new global Monte Carlo analysis of parton distribution functions (PDFs) of the pion determined its valence quark distribution using Drell-Yan data from Fermilab and CERN and its sea quark and gluon PDFs from leading neutron electroproduction data from HERA [1]. While that analysis provided greater constraints at small parton momentum fractions $x$, the pion's gluon PDF remains...
Calculations at small $x$ are usually made in the eikonal approximation. This is the case in the Color Glass Condensate (CGC) effective theory where the propagation of high energy partons in the intense colour field of a hadron or nucleus, approximated by a shockwave, is described by Wilson lines. In this talk we will review attempts to go beyond the eikonal approximation in the CGC framework,...
Apart from a few anomalies, the majority of measurements at the LHC have been consistent with the Standard Model (SM). Searches of new physics signals beyond LHC energies is now being realized by studying available data with an effective field theory framework. In this talk, I present the results from a combined analysis of top quark and Higgs production measurements at the LHC using SM...
The transverse momentum dependent parton distribution functions (TMDPDFs) measure the transverse momentum of partons in a fast moving hadron, and is an important observable for the Electron-Ion Collider. The energy evolution of TMDPDFs is given by the Collins-Soper (CS) anomalous dimension, or the CS kernel, which is essential to the fitting of TMDPDFs from global cross section data at...
We present a new global QCD analysis of inclusive unpolarized and polarized DIS data, using a Monte Carlo approach to simultaneously extract both the spin-averaged and spin-dependent PDFs. We focus on the high-$x$, low-$W$ region, where effects from power corrections, such as target mass corrections (TMCs) and higher twists, are particularly important. We quantify the effects on the extracted...
I present new theoretical results at approximate N$^3$LO for double-differential distributions in top-quark transverse momentum and rapidity. The higher-order corrections are from NNLL resummation of soft-gluon contributions. The corrections are very significant and they reduce theoretical uncertainties. The theoretical predictions are in very good agreement with recent LHC data.
We present results on the nucleon valence quark distribution extracted from Lattice QCD simulations, using a gauge ensemble of $N_f=2+1$ Wilson-Clover fermions with a pion mass of $m_\pi = 350$ MeV and lattice spacing of about $a=0.093$ fm. We obtain reduced Ioffe Time Distributions (rITDs) by computing appropriate matrix elements on the lattice, and elaborate on the extraction of the desired...
We present the first measurements of diffraction in $\sqrt{s_{NN}}=8.16$ TeV proton-lead collisions within CMS. The very large angular coverage of CMS is used to tag rapidity gaps on both the proton-going and lead-going sides and to identify both pomeron-lead and pomeron-proton topologies. Since the previous highest energy measurement of these processes was at $\sqrt{s_{NN}}=30$ GeV, the...
Comprehensive measurements of differential cross-sections of top-quark-antiquark pair-production are presented. The measurements are performed in the lepton+jets and the all-hadronic channels which allow for reconstruction of the top-quark and top-quark-pair kinematic distributions. The two channels are complementary in terms of range and resolution for several variables. Both measurements use...
Jet production is the primary signal for hard scattering of the partons inside protons, which is one of the dominant processes in proton-proton collisions at the RHIC energies. The jet double-spin asymmetries $A_{\text{LL}}$, measured at the STAR detector in polarized $pp$ collisions, remain one of the main sources of constraint for the polarized gluon parton distribution function $\Delta g$....
The LHeC provides a comprehensive physics programme with strong implications on that of the HL-LHC. We will present a chapter of the 2020 LHeC White Paper, that is firstly the implications of the precise determination of proton PDFs at the LHeC on the measurement of key SM parameters at the HL-LHC: EW mixing angle, W mass and their impact on EW precision measurements. Then we will address the...
The most precise measurements of Higgs boson cross sections, using the framework of simplified template cross sections, are obtained from a combination of the measurements performed in the different Higgs boson decay channels. This talk presents the combined measurements, as well as their interpretation.
In recent years, parton distributions have been calculated from ab initio QCD using non-perturbative lattice field theory. In this presentation, I focus on a Lorentz invariant generalization of the Ioffe time distribution which can be calculated directly on the Lattice. Just like experimental cross sections, these matrix elements can be factorized into the PDF. I present our latest results for...
The CMS Precision Proton Spectrometer consists of tracking and timing detectors placed close to the beam at about 200m from the interaction point. The goal of PPS is to measure the kinematic parameters of the protons scattered in interactions where at least one of them emerges intact. Silicon tracking detectors measure the momentum lost by the proton and diamond timing detectors measure its...
The Solenoidal Tracker at the Relativistic Heavy Ion Collider (STAR) experiment probes the gluon helicity distribution $\Delta G(x)$ using collisions of longitudinally polarized protons at $\sqrt{s} = $ 200 GeV and $\sqrt{s} =$ 510 GeV. Access to $\Delta G(x)$ is possible through the double spin asymmetries $A_{LL}$ in gluon-dominated hard scattering processes of inclusive jet and di-jet...
The hard scattering process in which two top-quark-antiquark pairs are produced is also called four-top-quarks production and is predicted to have a small cross-section of 12 fb in the Standard Model. This very rare process has not been observed yet. The background mainly comes from top-quark-antiquark production in association with heavy flavor jets. In this presentation, two analyses are...
We present a quantitative assessment of the impact the future Electron-Ion Collider would have in the determination of parton distribution functions in the proton and parton-to-hadron fragmentation functions through semi-inclusive deep-inelastic electron-proton scattering data.
Specifically, we estimate the kinematic regions for which the forthcoming data are expected to have the most...
The Higgs boson pair production via gluon fusion at high-energy hadron colliders, such as the LHC, is vital in deciphering the Higgs potential and in pinning down the electroweak symmetry breaking mechanism. In this talk, I will present the NNNLO QCD calculations in the infinite top-quark mass limit and predictions for both the inclusive and differential cross-sections. At the inclusive...
In the Ingelman-Schlein approach for hard diffraction the cross sections can be factorized into diffractive PDFs and perturbatively calculable partonic coefficient functions. The diffractive PDFs can be determined in a global QCD analysis using data for diffractive processes in DIS in a similar manner as for inclusive PDFs. However, it has been observed that this factorization breaks down in...
We present NLOPS matched predictions for $pp \to \ell \nu_\ell j j b \bar b$ at $\alpha^4 \alpha_s^2$ within the POWHEG BOX RES framework. This process is dominated by top-pair production and decay in the semileptonic channel. The hadronic decay of the W-boson is considered in an approximation that allows for consistent inclusion of the contributions from $t\bar t$ and $Wt$ single-top...
The most precise measurements of Higgs boson single and double Higgs production cross sections are obtained from a combination of measurements performed in different Higgs boson production and decay channels. While double Higgs production can be used to directly constrain the Higgs boson self-coupling, the latter can be also constrained by exploiting higher-order electroweak corrections to...
At RHIC energies high pT direct photons are mainly produced by the quark-gluon Compton scattering process. Being not disturbed by fragmentation processes, they provide access to initial condition of partonic collisions. Direct photon production in pp collisions serves an ideal probe for gluon parton distribution functions (PDF), whereas quark PDFs are well constrained by deeply inelastic...
We asses the impact of the future Electron-Ion Collider
on the collinear gluon helicity distribution ($\Delta g$).
In particular, we study the constraining power of longitudinally
polarized inclusive deep-inelastic scattering on $\Delta g$
using the $Q^2$ range covered by the EIC kinematics.
Latest results on inclusive and differential top quark pair and single top quark production cross sections are presented using proton-proton collision data collected by the CMS experiment. The differential cross sections are measured as a function of various kinematic observables of the top quarks and the jets and leptons of the event final state. The results are confronted with precise theory...
We present the first attempt to access the x-dependence of the gluon polarized and strange parton distribution functions (PDFs) from lattice calculations, using large-momentum effective theory (LaMET). LaMET methods have been applied to a wide variety of isovector nucleon distributions and valence pion distributions. However, the polarized gluon and strange-quark distributions have not yet...
Top quark production can probe physics beyond the SM in different ways. The Effective Field Theory (EFT) framework allows searching for BSM effects in a model independent way. CMS experiment is pioneering EFT measurements that move towards using full potential of the data in the most global way possible. Searches for flavour-changing neutral currents (FCNC) and anomalous top quark interactions...
The virtual photon asymmetry $A_1$ is one of the fundamental quantities that provide
information on the spin structure of the nucleon. The value of A1 at high $x_{Bj}$
is of particular interest because valence quark dominate in this region, which makes
it a relatively clean region to study the nucleon spin structure. There are several
theoretical calculations that apply to the high x...
Measurements of top quark properties using data collected by the CMS experiment at 13 TeV are presented. They include direct measurements of properties or extractions using differential cross section measurements. Among them, the latest results on top mass and its running, top Yukawa coupling, the top sector of the CKM matrix, ttbar forward backward asymmetry will be discussed.
Lattice QCD and global PDF analyses have both made significant strides in recent years. Much of this progress owes to the growing availability of computational resources as well as steady theoretical advances in lattice gauge theory and perturbative QCD. In this context, it is increasingly suggested that the output of lattice QCD calculations could serve as important input to global fits for...
Most hard scattering processes at the LHC lead to breakup of the proton because of the single-parton exchange of the proton. However, since the proton is an electrically charged object, quasireal photon-exchange interactions can also take place. Since photons are color-singlet, sometimes the protons remain intact after the interaction, and these can be detected with forward proton detectors...
We present NLO QCD predictions for dijet photoproduction on heavy nuclei for three future collider options at CERN, the LHeC, its high-energy (HE) version and the electron-hadron/nucleus version of the FCC, and compare them to our previous predictions for the EIC. We focus on the potential of these colliders to constrain nuclear parton densities, in particular in the small-x region, based on...
Using a newly proposed formalism which generalizes the Color Glass Condensate formalism and extends it to large Bjorken $x$, we calculate the dijet double differential cross section and investigate its properties for different kinematics; from small $x$ to large $x$ and from low to high transverse momenta.
Jets, clusters of collimated particles, produced from parton scatterings in high energy
proton-proton collisions are an effective tool to study the internal proton structure. At center of mass
energies of $\sqrt{s} = $ 200 and 510 GeV, jet production is dominated by the quark-gluon, $qg$ and
gluon-gluon, $gg$, scattering processes. The STAR experiment at the Relativistic Heavy Ion...
Heavy quarkonium production provides valuable grounds to explore fundamental QCD dynamics with multiple scales. Thus far, NRQCD factorization has been successful in describing many features of the data. Despite many theoretical efforts at NLO accuracy, however, there are still unresolved issues, including the lack of a full understanding of quarkonium polarization at high $p_t$. One...
We determine the small Bjorken $x$ asymptotics of the quark and gluon orbital angular momentum (OAM) distributions in the proton in the double-logarithmic approximation (DLA), which resums powers of $\alpha_s \ln^2 (1/x)$ with $\alpha_s$ the strong coupling constant. Starting with the operator definitions for the quark and gluon OAM, we simplify them at small $x$, relating them, respectively,...
The proposed high luminosity high energy Electron Ion Collider (EIC) will explore the proton/nuclear structure, search for gluon saturation and precisely determine the nuclear parton distribution functions (nPDFs) in a wide x-$Q^{2}$ phase space. Heavy flavor and jet measurements at the future EIC will allow us to better constrain the nPDFs within the poorly constrained high Bjorken-x region,...
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial
upgrade of the B factory facility at KEK in Tsukuba, Japan. It aims to record a factor of 50 times
more data than its predecessor. The experiment completed a commissioning run in 2018, and
began full operation in early 2019. Belle II is uniquely capable of studying the so-called "XYZ"
particles:...
Recent multiboson results at CMS are presented.
We find the small-$x$ asymptotics of the quark helicity distribution in the large-$N_c$ & $N_f$ limit by numerically solving small-$x$ evolution equations derived in earlier works, where $N_c$ is the number of quark colors and $N_f$ is the number of quark flavors. Previously, those evolution equations were solved only in the large-$N_c$ limit. We find that $\Delta q$ oscillates as a function...
The discovery of pentaquark candidates in Lb->JpsipK decays at LHCb has opened a new field in exotic spectroscopy. Analysis of full dataset of b-hadron decays collected during Run I and II provides opportunities to examine the established states with better precision, their investigation in new decay modes and for searches of new exotic hadron candidates. Recent results of these studies will...
Measurements of electroweak boson pair production at the LHC constitute a stringent test of the electroweak sector and provide a model-independent means to search for new physics at the TeV scale. In this talk, we present recent results from the ATLAS experiment for WW, ZZ and Z𝛾 production in proton-proton collisions at √s=13 TeV. The measurements in each channel exploit the leptonic decays...
The worldline representation of quantum field theory is a powerful framework for the computation of perturbative multi-leg Feynman amplitudes. In particular, in gauge theories, it provides an efficient way, via point particle Grassmann functional integrals, to compute spinor and color traces in these amplitudes. In my talk I will give a short introduction into the worldline formalism and show...
The associated production of vector bosons V (W, Z or gamma) and jets originating from heavy-flavour (c or b) quarks is a large background source in measurements of other standard model processes, Higgs boson studies, and many searches for physics beyond the SM. The study of events with a vector boson accompanied by heavy-flavour jets is crucial to refine the theoretical calculations in...
Recently, there has been increasing recognition that jet measurements can be an important component of the physics program at the future Electron-Ion Collider (EIC). Jets are a more effective proxy for partonic kinematics than the single hadron measurements usually performed in Deep Inelastic Scattering experiments, while substructure techniques can be used to examine non-perturbative effects...
A statistical combination of the search results for the X(5568) resonance decaying into $B_s π$ is reported, based on published results from the ATLAS, CMS, CDF and LHCb Collaborations.
A narrow structure in the invariant mass distribution of $B^0_s π^±$ has been observed by the D0 Collaboration with a mass value of 5568 MeV but not confirmed by any of the latest searches from the other...
We present prospects for the direct measurement of ratios of differential cross sections for the production of Z and Higgs bosons in proton-proton collisions, using data taken by CMS during the LHC Run II. The aim of the study is to investigate soft and hard gluon emission in the initial state for Higgs and Z production mechanisms. Hence, we focus on variables known to be sensitive to the...
We calculate the single transverse spin asymmetry (STSA) in polarized proton-proton and polarized proton-nucleus collisions ($A_N$) generated by a partonic lensing mechanism. The polarized proton is considered in the quark-diquark model while its interaction with the unpolarized target is calculated using the small-x/saturation approach [1], which includes multiple rescatterings and small-x...
Jet production measurements have represented one of the cornerstones of global PDF analyses since the early days of the Tevatron. Here we critically revisit the impact of jet production measurements from the LHC at 7 and 8 TeV within a global PDF fit by exploiting recent progress in NNLO QCD calculations. For the first time, we demonstrate that dijet production measurements can be successfully...
The associated production of vector boson with quarkonia is a key observable for understanding the quarkonium production mechanisms, including the separation of single and double parton scattering components.
This talk will present the latest measurements from ATLAS on quarkonium production, including associated production, and recent results from heavy flavour production. In addition, recent...
The Election-Ion Collider (EIC) is a next generation accelerator, which is designed to answer longstanding questions in nuclear physics. The EIC with its wide range of center of mass energies from 20 to 140 GeV, polarized beams, and beam species, as well as high luminosity, is designed to precisely image the quarks and gluons and their interactions, and to explore the new QCD frontier of...
In the Color Glass Condensate effective theory framework, the evolution of high energy scattering amplitudes with collision energy is given by thy Balitsky-Kovchegov (BK) equation. It is usually derived from the JIMWLK hierarchy in the in the large-Nc limit. The next-to-leading order evolution equation for the 2-point correlator, related to the total deep inelastic scattering cross section,...
Recent experimental measurement of deeply virtual Compton scattering off the neutron by Hall A JLab collaboration [Benali et al., Nat. Phys. 16, 191 (2020)] provides welcome addition to the endeavor of determination of nucleon GPDs. This should be an important step towards both determination of elusive GPD E and flavor decomposition of DVCS amplitude. We will describe repercussions of this...
Latest results about searches for new resonances with the CMS experiment will be presented. Prospects for Run III and beyond will be also discussed.
The CJ15 global next-to-leading-order analysis of PDFs utilized, amongst others, inclusive and tagged DIS structure function data from Jefferson Lab (JLab) and high-precision charged lepton and W-boson asymmetry data from Fermilab. As an extension to the CJ15 analysis, new JLab Hall A and C data from experiments jl00106F2, e06009d, e99118, jlcee96 and e03103, and Hall B data from the BONuS and...
We present the first computation of the next-to-leading order (NLO) photon+dijet impact factor in e+A DIS at small $x$ in the framework of the Color Glass Condensate (CGC) effective field theory. When combined with the recent derivation of JIMWLK small $x$ evolution to next-to-leading logarithm (in $x$) accuracy, this result provides us with a prediction of the photon+dijet cross-section in...
Using a recent extraction of deeply virtual Compton scattering (DVCS) Compton form factors, done within the PARTONS framework, we derive timelike Compton scattering (TCS) amplitudes and calculate TCS observables only assuming leading-twist dominance. In the framework of collinear QCD factorization, the leading-twist scattering amplitudes for DVCS and TCS are intimately related thanks to...
The heavy quarkonium together with b-hadrons provide a rich material for testing effective theories of strong interaction via production, decay and spectroscopy studies. This talk presents recent progress on these studies at LHCb obtained using the full dataset collected during runs I and II of the LHC.
Many extensions to the Standard Model predicts new particles decaying into two bosons (W, Z, photon, or Higgs bosons) making these important signatures in the search for new physics. Searches for such diboson resonances have been performed in final states with different numbers of leptons, photons and jets and b-jets where new jet substructure techniques to disentangle the hadronic decay...
Using data from a recent reanalysis of neutron structure functions extracted from inclusive proton and deuteron DIS, we re-examine the constraints on the shape of the $\bar d − \bar u$ asymmetry in the proton at large parton momentum fractions $x$. A global analysis of the proton–neutron structure function difference from BCDMS, NMC, SLAC and Jefferson Lab DIS measurements, and of Fermilab...
The LHeC and the FCC-eh will open a new realm in our understanding of nuclear structure and the dynamics in processes involving nuclei, in an unexplored kinematic domain. In this talk we will review the most recent studies as shown in the update of the 2012 CDR recently delivered. We will discuss the determination of nuclear parton densities in the framework of global fits and for a single...
Ioffe time essentially quantifies the distance along the lightcone that the quark fields that enter the correlator describing the Parton Distribution Function (PDF) are separated by. In this sense, it is a natural candidate for clearly separating the short distance physics from the long distance physics. We study how the behavior of the psrton distribution in Ioffe time can be mapped out given...
The ATLAS experiment has performed accurate measurements of mixing and CP violation in the neutral B mesons, and also of rare processes happening in electroweak FCNC-suppressed neutral B-mesons decays.
This talk will focus on the latest results from ATLAS, such as rare processes: B^0_s → mu mu and B^0 → mu mu; and CPV in Bs to Jpsi Phi, where Standard Model predicts the CP violating phase,...
We formulate a general approach to the inclusion of theoretical uncertainties, specifically those related to the missing higher order uncertainty (MHOU), in the determination of parton distribution functions (PDFs). We demonstrate how, under quite generic assumptions, theory uncertainties can be included as an extra contribution to the covariance matrix when determining PDFs from data. We...
We study the relative importance of double Bethe-Heitler, single Bethe-Heitler and QCD processes in the electroproduction of two photons with a large invariant mass, for both JLab and EIC kinematics.
Many theories beyond the Standard Model (BSM) predict new
phenomena at the highest energies accessible by the LHC. These often give rise to heavy resonances consisting of either isolated high-pt leptons or pairs of jets, either exclusively or in conjunction with other objects. Alternatively, should new physics be beyond the scale of the LHC, non-resonant signatures in these final states can...
The agreement between calculations inspired by the resummation of energy logarithms, known as BFKL approach, and experimental data in the semi-hard sector of QCD has become manifest after a wealthy series of phenomenological analyses. However, the contingency that the same data could be concurrently portrayed at the hand of fixed-order, DGLAP-based calculations, has been pointed out recently,...
We present a new, simultaneous extraction of spin-averaged and spin-dependent PDFs within a multi-step Monte Carlo analysis. Utilizing data from inclusive jet production in unpolarized and polarized proton-proton and proton-antiproton collisions, we determine for the first time the spin-dependent gluon distribution, $\Delta g(x)$, at the same time as the unpolarized gluon PDF, $g(x)$....
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. With this data set, Belle II will be able to measure...
The form factors of the energy-momentum tensor (EMT) contain a wealth of information about the nucleon. At the density level, this information can be described in terms of energy, pressure, shear forces and angular momentum distributions inside the nucleon. In this talk we present recent results on the associated 2D densities of the energy-momentum tensor in the bag model, formulated in the...
Since the discovery of the Higgs boson with the mass of about 125 GeV much effort has been spent looking for further scalars, which are motivated in many scenarios. Here we report on searches for new neutral heavy Higgs bosons decaying to pairs of third generation fermions: tau leptons or b quarks. These searches are based on full Run2 data of the ATLAS experiment at the LHC.
We perform analysis of the pole structure of the BFKL eigenvalues in Mellin space with different forms of the kinematical constraint imposed on the low x evolution. We find that all of them generate the same leading anti-collinear poles which agree with BFKL up to NLL order and up to NNLL in N=4 sYM. The coefficients of subleading poles vanish up to NNLL order for all constraints and we prove...
We present a comprehensive review of existing Monte Carlo methods used in global QCD analyses of parton distribution functions. We critically examine the interpretability of uncertainties on extracted parton distributions against nested sampling and the more traditional Hessian approach. We show how in some cases the inclusion of resampling, partition, and cross-validation of the data can...
We present the use of machine learning to reconstruct deep inelastic scattering (DIS) kinematics. In particular, we trained deep neural networks to reconstruct $x$ and $Q^2$ based on information from the lepton and the hadronic system in $e^{\pm}p$ scattering at the ZEUS experiment at HERA. These models were trained by a careful selection of Monte Carlo events. The results from the neural...
Deep inelastic scattering (DIS) total cross section data at small-x as measured by the HERA experiments is well described by Balitsky-Kovchegov (BK) evolution in the leading order dipole picture [1-3]. Recently the full Next-to-Leading Order (NLO) dipole picture total cross sections have become available for DIS [4-6], and a working factorization scheme has been deviced which substracts the...
PHENIX has made a comprehensive measurement of low p$_\mathrm{T}$ direct photon yield in Au+Au collisions at 200 GeV that show both a large yield and a large azimuthal anisotropy produced. The mechanism for such simultaneous large production is not well understood yet.
Recently the PHENIX collaboration has improved on those measurements by using the Au+Au data collected in 2014 which...
Experimental measurements of Drell-Yan (DY) vector-boson production
are available from the Large Hadron Collider (LHC) and from lower-energy collider and fixed-target experiments. In the low transverse momentum end of DY spectra, important for the extraction of the $W$-boson mass at the LHC, QCD contributions from non-perturbative Sudakov form factors and intrinsic transverse momentum become...
While the investigation of TMDs is a major objective of the EIC, Double Parton Ditributions (DPDs) are crucial for a first principle QCD description of double parton interactions at LHC, which contribute to the standard model background for various BSM searches. Both groups of functions are genuinely non-collinear and non-perturbative. The non-collinearity required the development of new...
I present ongoing progress towards a new global PDF analysis from the NNPDF Collaboration: NNPDF4.0. As compared to its predecessor, NNPDF3.1, it contains several improvements from the theory input, dataset, and methodology points of view. NNPDF4.0 includes a large number of new experimental measurements from HERA, ATLAS, CMS, and LHCb, among others for the first time the HERA jet...
Investigating the three-dimensional structure of the nucleon has been an active field of research, especially so since the introduction of the generalized parton distributions (GPD). Research focused on this three-dimensional structure continues to be central to the hadron physics program at facilities like Jefferson Lab. The GPD formalism provides a unified description of many important...
Using the formalism of the light-cone wave function in pQCD together with the hybrid factorization, we compute the cross-section for two and three particle production at forward rapidities in proton-nucleus collisions. We focus on the quark channel, in which the three produced partons -- a quark accompanied by a gluon pair, or two quarks plus one antiquark -- are all generated via two...
The muonic-deuterium spectroscopic measurements obtained a significantly smaller (5.6 $\sigma$) deuterium charge radius as compared to the CODATA 2014 value. It is also 2.6 $\sigma$ away from the combined value of the proton charge radius from the muonic-hydrogen measurements and the isotope shift value from ordinary hydrogen and deuterium measurements, indicating an effect from the neutron...
Precision measurements of the production cross-sections of W/Z boson at LHC provide important tests of perturbative QCD and information about the parton distribution functions for quarks within the proton. We present measurements of fiducial integrated and differential cross sections for inclusive W+, W− and Z boson production using data collected by the ATLAS experiment at center-of-mass...
Photon-induced processes in proton-proton interactions have become recently very topical. The large energy at the LHC, when combined with relatively large luminosity at run II, allows to start the exploration of such processes.
We discuss production of $W^+ W^-$ pairs and $t \bar t$ quark-antiquark pairs in proton-proton collisions induced by two-photon fusion including, for a first time,...
We present the computation of exclusive and inclusive dijet production in electron-proton and electron-nucleus collisions at small-x within the Color Glass Condensate effective field theory. We compute the cross-sections differentially in mean dijet momentum and momentum imbalance, as well as its corresponding elliptic anisotropy. For exclusive dijet production, we employ a dipole model with...
Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under...
A. SHABETAI (for the ALICE Collaboration)
Highly energetic point-like partons produced in a hard scattering will lead to a parton shower which will be fragmenting into a hadronic spray of particles called a jet. The partonic stage of such shower can be calculated from first principles using the QCD factorisation theorem. Jet substructure observables, such as jet fragmentation functions...
The study of the associated production of vector bosons and jets constitutes an excellent testbench to check numerous QCD predictions. Total and differential cross sections of vector bosons produced in association with jets have been studied in pp collisions at 7, 8 and 13 TeV center-of-mass energies. Differential distributions as function of a broad range of kinematical observables are...
We present cross sections for the weak bosons measured by the STAR experiment at
RHIC in unpolarized proton-proton collisions at $\sqrt{s}$ = 500(510) GeV. The results combine data from run 2011, 2012, and 2013, corresponding to an integrated luminosity of 350~$pb^{-1}$. The differential $Z^{0}$ cross section measured as a function of the boson's $p_{T}$, provides important constraints on...
In the search for a clear signal of underlining BFKL dynamics in high-energy diffractive processes the Mueller-Tang jet observables have been proven to be a particularly fortunate choice.
Despite unavoidable unperturbative effects that can affect the rapidity gap signature good agreement was found between the BFKL predictions and the Tevatron data.
The extent of the agreement was partially...
A number of PDF sets have either recently been produced (CT18), or will be coming out in the near future (from MMHT, NNPDF), utilizing high statistics, high precision data from the LHC. In 2015, an intense year-long benchmarking exercise was carried out among the global PDFs then available (CT14, MMHT2014, NNPDF3.0). This exercise allowed a better understanding of the relative influence of the...
The internal structure of the Nucleon has been studied for more than 60 years providing a very good understanding of its dynamics. On the other hand, the internal structure of the pion, which is in principle the simplest QCD bound state, is less explored, and its Parton distribution functions less known. Nevertheless, the presence of a virtual meson-cloud surrounding the Nucleon has been...
Heavy flavor production is an ideal tool to study the properties of the QCD medium created at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). The kinematic coverage and production mechanisms of the heavy flavor are different between RHIC and LHC. The PHENIX experiment has a comprehensive physics program which studies open heavy flavor and quarkonium production...
In this talk, I am going to introduce our recent works about TMD factorization and resummation for Z boson tagged jets production at the LHC, which can be used to study the proton TMD structure and QCD factorization violation effects. We investigated jet production with the standard jet axis and also the winner-take-all axis. In the first case, we derived an all-order factorization formula,...
We present an extraction of unpolarized transverse-momentum dependent (TMD) parton distribution functions (PDFs) based on a fit on data from Drell-Yan processes in different experiments and kinematic ranges, including in particular LHC experiments. The analysis is performed in the TMD factorization framework with perturbative accuracy up to next-to-next-to-next-to-leading-log (N$^3$LL),...
A study of events where the two leading jets are separated by a large pseudorapidity interval void of particle activity, known as jet-gap-jet events, is presented. The jets have transverse momentum pT, jet > 40 GeV and pseudorapidity 1.4 < | ηjet | < 4.7, and opposite-signed pseudorapidities ηjet1 · ηjet2 < 0. The analysis is based on an inclusive dijet data sample collected by the CMS...
I will discuss complications that arise in the factorization of hard processes differential in transverse momentum due to ambiguities in the transition from the small to large transverse momentum regions. I will relate questions about the region transition to the implementation of evolution in transverse momentum sensitive processes such as spin asymmetries. In addition, I will relate the...
The lack of a neutron target has resulted in a decades-long effort to understand the free neutron structure in order to test SU(6) symmetry breaking mechanisms. Approaches to address this open question traditionally extract the free neutron structure from proton + deuterium DIS data (and various other reactions such as jet production or W charge asymmetries).
Here we present a novel...
The central issue of the presentation will be theoretical study of four charged pion photoproduction that come from ultraperipheral heavy-ion collision. I take into account the single photoproduction of the radial excitations of the $\rho^0$ vector meson. The analysis includes a contribution from the incoherent sum of the $\rho'(1450)$ and $\rho''(1700)$ vs single $\rho(1570)$ vector mesons. I...
The talk will focus on physics goals with Run-III data and the status of ongoing and planned detector upgrades. A brief view on software upgrades and an outlook towards HL-LHC wiil also be presented.
I will present a new class of jet/event substructure observable called collinear drop and its use in the search for novel signatures of jet modifications and medium responses. I will demonstrate using Monte Carlo simulations generated with Jewel how underlying jet-medium interactions can be systematically examined using collinear-drop observables. I will also give analytic insights on the...
The span of uncertainties of the PDFs obtained in a global analysis depends on criteria for selection of acceptable PDF fits. I review several such criteria for estimating the goodness of fit in a large-scale analysis such as CT18, where they are applied in addition to the commonly used value of the global log-likelihood. On the example of CT18(Z) predictions for electroweak precision...
The electromagnetic field of a fast charged particle can be described as a flux of quasi-real photons whose intensity is proportional to the square of the electric charge of the particle. In the case of lead ions circulating in the LHC there are copious photonuclear interactions. If the impact parameter of the colliding lead ions is larger than the sum of their radii, photon-induced processes...
Measurements of the internal properties of jets allow QCD to be studied at a new regime at a hadron collider. In this talk, we discuss recent measurements of jet substructure and jet fragmentation that were performed using data collected by the ATLAS experiment at a centre-of-mass energy of √s=13 TeV. For jet substructure, a comprehensive suite of substructure observables are measured for...
In the global analysis of nuclear Parton Distribution Functions
(nPDFs), one of the major sources of debate is how to include the
neutrino Deep Inelastic Scattering (DIS) data. The controversy comes
from the precise NuTeV neutrino DIS data which might indicate an
incompatibility with neutral current charged lepton DIS data. The
compatibility of NuTeV data was studied independently by...
The transverse momentum spectrum of low mass Drell-Yan (DY) production at low
center-of-mass energies $\sqrt{s}$ is calculated by applying transverse momentum
dependent (TMD) parton distributions obtained from the Parton Branching (PB)
evolution method, combined with the next-to-leading-order (NLO) calculation of
the hard process in the MCatNLO method. We compare our predictions with...
In recent years the STAR Collaboration collected a large sample
of ultra-peripheral heavy-ion collisions. The photoproduction of
J/Psi vector mesons is sensitive to the gluon content of the target
nucleon or nucleus. We will present results from a statistically
large sample of J/Psi production in Au+Au collisions. A significant
result comes from the study of the pT distributions, which...
We report on our progress of including the latest LHC p-Pb measurements on W$^\pm$, dijet, and D-meson production into the EPPS analysis of nuclear PDFs. The new data are observed to set strong constraints particularly on the gluons across a wide range in the momentum fraction $x$.
We study the angle between i) the standard jet axis, ii) the axis of a jet
which has been groomed using soft drop, with reduced sensitivity to soft radiation, iii) the
jet axis obtained with the winner-take-all recombination scheme, which is insensitive to
soft radiation at leading power. We calculate the distributions for these angles at next-to-leading logarithmic accuracy, including...
The LHeC and the FCC-eh, offer unique prospects for the measurement of EW parameters and top properties in energy frontier, luminous ep scattering. In this talk we will revisit the determination of $Z$, $W$ and top mass through inclusive measurements. Next, we will show the possibilities for the determination of the vector and axial couplings of light quarks, of the effective weak mixing angle...
I will present the program “reSolve”, a publicly available tool for calculating the resummed contributions to transverse momentum and other spectra. It makes use of the Catani-de Florian- Grazzini resummation formalism in impact parameter space and Mellin space and exploits its largely process-independent nature to be general purpose, applying to any final state excluding coloured particles....
I will discuss the cross section for the production of two unpolarized hadrons in the large transverse momentum configuration from $e^+ e^-$ annihilation, which is based on collinear fragmentation functions (FFs). Comparing with standard transverse-momentum-dependent (TMD) FF-based predictions intended for the small transverse momentum region, when the center of mass energy is not very large...
Precision physics calculation are now slowly becoming a standard in Monte Carlo event generation. In particular now, many MC generators allow the possibility to automatically include higher order EW-corrections on top of the usual QCD ones. Nevertheless these corrections can become quite computationally intensive, in particular for many-particles final states (or processes where one includes...
A complete understanding of the nucleon spin structure requires the knowledge of unpolarized parton distribution functions, helicity distribution functions, and the transversity distributions. Transversity, which describes the transverse spin structure of quarks in a transversely polarized proton, is the most difficult to probe and is still quite unconstrained in global analyses. It is...
Jet substructure represents a cornerstone in current BSM searches at the LHC. Further, it is instrumental in the on-going endeavor to pinpoint the effect of a hot, thermal medium, namely the QGP, on QCD dynamics. In this talk, based on [1], I will present a new set of jet substructure observables and an associated grooming technique rooted on identifying the hardest splitting in an angular...
Understanding the structure and dynamics of hadron structure entails the question how the roughly 1-GeV mass scale that characterizes the proton and atomic nuclei appears, and in stark contrast why are composite Goldstone bosons such as pions and kaons abnormally light in comparison. To understand this a strong interplay between experiment and theory is crucial. The talk will present the...
We investigate saturation e?ffects in ep scattering as well as in ultraperipheral pA and AA collisions at small x with four variants of the impact parameter dependent color dipole model: with and without gluon saturation and with and without a novel mechanism that suppresses unphysical dipole radii above the confinement scale.
We show that ep scattering at HERA can be very well described by...
Studies on the production of light- and heavy-flavour baryons are of prominent importance to characterise the partonic phase created in ultrarelativistic heavy-ion collisions and to investigate hadronization mechanisms at the LHC, in particular through the study of the evolution of the baryon-over-meson production ratio as a function of the transverse momentum. Measurements performed in pp and...
The nCTEQ15 fit of nuclear Parton Distribution Functions (nPDFs)
includes data on Deep Inelastic Scattering (DIS), Drell-Yan (DY) and
single-inclusive pion production. In preparation for the upcoming
nCTEQ nPDF update, we present an analysis assessing the impact of
additional single-inclusive hadron production data in a nCTEQ15-like
fit. Specifically we look at pion production data from...
Pairing of nucleons at short-range is a universal phenomenon in nuclei, and has far-reaching implications outside of understanding traditional nuclear structure. Short-range correlations (SRCs) have been extensively studied over the past few years, using facilities around the world. Although this remarkable progress has brought deep, new insight into the nature of SRCs, there are still many...
The associated production of top quarks with neutral bosons is measurable in 13 TeV pp LHC collisions thanks to the unprecedented accumulated luminosity. It directly probes top quark couplings to photons and Z bosons and tests for deviations from the standard model.Three measurements are presented. The cross sections for the production of top quark pairs in association to a photon (ttgamma) or...
We present a model with which we predict the cross sections for exclusive and dissociative photo and electroproduction of light and heavy vector mesons off protons; the model describes correctly available experimental data. The model is based on the color-dipole approach and incorporates geometric fluctuations of the target-proton partonic structure in the impact-parameter plane. The number of...
Resolving the quark and gluon structure of nuclei has been a crucial aim of the QCD physics community since the discovery of the EMC effect. Such information is given by the nuclear parton distribution functions (nPDFs), which describe the collinear momentum substructure of nucleons bound within nuclei and are accessed via global QCD analyses of lepton-nucleus and hadron-nucleus measurements....
We present a new extraction of unidentified charged hadron collinear fragmentation functions (ffs) using a multi-step Monte Carlo analysis. The extraction utilizes available charged hadron data from e+/e- and SIDIS experiments including the most recent results from COMPASS.
The LHCb experiment at the Large Hadron Collider (LHC) at CERN is suited for studying various aspects of the theory of strong interaction, Quantum Chromo-Dynamics. One area of active research is to understand how hadrons are formed from scattered quarks and gluons, collectively referred to as partons, in energetic proton-proton collisions. The hadronization process is a non-perturbative...
We study the production of a single top quark in association with a heavy extra Z' at hadron colliders in new physics models with and without flavor-changing neutral-current(FCNC) couplings. We use QCD soft-gluon resummation and threshold expansions to calculate higher-order corrections for the total cross section and transverse-momentum distributions for tZ' production. The impact of the...
We show how exclusive vector meson production off light ions can be used to probe the spatial distribution of small-𝑥 gluons in the deuteron and 3He wave functions. In particular, we demonstrate how short range repulsive nucleon-nucleon interactions affect the predicted coherent J/Psi production spectra. Fluctuations of the nucleon substructure are shown to have a significant effect on the...
We outline a strategy to compute deeply inelastic scattering structure functions using a hybrid quantum computer [1]. Our approach takes advantage of the representation of the fermion determinant in the QCD path integral as a quantum mechanical path integral over 0+1-dimensional fermionic and bosonic worldlines [2]. The proper time evolution of these worldlines can be determined on a quantum...
The analysis of single transverse-spin asymmetries (SSAs) gives us tremendous insight into the internal structure of hadrons. For example, the Sivers and Collins effects in semi-inclusive deep-inelastic scattering (SIDIS), Sivers effect in Drell-Yan, and the Collins effect in electron-positron annihilation have been widely investigated over many years in order to perform 3D momentum-space...
In preparation for the era of the High-Luminosity LHC, it will be crucial to enhance the precision of theoretical predictions for BSM-sensitive observables in the electroweak and Higgs sectors. In many cases, such as the extraction of the $W$-boson mass, contemporary PDF uncertainties are a dominant limitation in the quest to achieve the necessary precision. In this talk, I will review this...
We present a theoretical formalism and associated results for soft-gluon resummation for $2 \rightarrow n$ processes in single-particle-inclusive kinematics.
We study exclusive quarkonium production in the dipole picture at next-to-leading order (NLO) accuracy, using the non-relativistic expansion for the quarkonium wavefunction. This process offers one of the best ways to obtain information about gluon distributions at small $x$, in ultraperipheral heavy ion collisions and in deep inelastic scattering. The quarkonium light cone wave functions...
We start with an overview of the recent results on charmonia and bottomonia production in electro- and photoproduction processes. An emphasis will be given to the careful treatment of light-front wavefunctions of heavy quarkonia in the potential approach formulated in the color dipole picture. A significant role of spin effects and the D-wave component is found and quantified. Our light-front...
The CJ (CTEQ-Jefferson Lab) Collaboration provides a global fit of parton distribution functions (PDFs) with a special emphasis on the large x region. The latest fit (CJ15) implemented deuteron nuclear corrections at the parton level, and included data that were sensitive specifically to the neutron. These nuclear corrections allow for a calculation of the F2 structure functions of the proton,...
Transverse spin phenomena have challenged our understanding of the structure of the nucleon and the strong interaction in many ways. The single transverse spin asymmetries that were measured at RHIC continue to challenge us as the contributions from initial and final state effects as well as the contributions from various flavors are not well understood. The PHENIX experiment has contributed...
The factorization of short-distance partonic cross sections from universal nonperturbatively-generated kinematic distributions is fundamental to phenomenology at hadron colliders. It has been predicted however that certain observables cannot be factorized in the usual way, even at high energies. Specifically, observables that are sensitive to momenta transverse to the direction of an energetic...
Possible electroweak and beyond the Standard Model searches at the future Electron-Ion Collider will be discussed. Measurements of the charged current reactions, parity violating asymmetries, as well as possible searches for e-tau charged lepton flavor violation will be reviewed. This talk will discuss importance of the beam polarization, high luminosity and benefits of the positron beam.
We analyze within the JAM framework the impact on unpolarized parton distributions of heavy-flavor production measurements in deep inelastic scattering. In particular, we investigate the recent combined results of inclusive and heavy-flavor production cross sections at HERA, which impose additional constraints on the gluon and the sea-quark distributions at low $x$.
We perform a systematic study on the twist-3 gluon distribution and fragmentation
functions which appear in the collinear twist-3 factorization for hard inclusive
processes. Three types of twist-3 distribution and fragmentation functions,
i.e., intrinsic, kinematical and dynamical ones, which are necessary to describe
all kinds of twist-3 cross sections, are related to each other by...
The status of the three-loop heavy-flavor corrections to unpolarized and polarized deep-inelastic scattering is reviewed. We discuss the analytic results on the single and two-mass corrections and also outline the consequences for the variable flavor number scheme in high energy hadronic scattering and heavy quark distribution functions.
In ultra-relativistic heavy-ion collisions, one expects copious rates of γγ processes through the interaction of the large electromagnetic fields of the nuclei, which can produce new particles (e.g. leptons) or even lead to light-by-light scattering via loop diagrams. The latter process is a notable prediction of QED and was only recently observed by ATLAS using the full 2018 dataset. In...
We present our study of proton structure functions in view of the CLAS12 experiments planned in the near future, which are to study electron scattering observables at a wide $Q^2$ range and with high precision in x. CLAS experiments have achieved major advances in the study of the $N^∗$ region of the electroproduction spectrum, and the data on electrocouplings of the many baryon resonances in...
We report on the measurement of the Central Exclusive
Production of charged particle pairs $h^{+}h^{-}$ ($h = \pi, K, p$)
with the STAR detector at RHIC in proton-proton collisions at
$\sqrt{s} = 200$ GeV. The charged particle pairs produced in the
reaction $p+p \rightarrow p^\prime+h^{+}h^{-}+p^\prime$ are reconstructed from
the tracks in the central detector and identified using the...
Measurements at the EIC have stringent requirements on high luminosity and acceptance of the collision final state particles, particularly in the directions along the beamline or, equivalently, extremely high rapidity. Accessing the EIC physics of interest requires unprecedented integration of the interaction region and detector designs. In this presentation, we review current detector...
Through the 21st and 22nd International Workshop on Deep Inelastic Scattering, a possibility of the non-perturbative contribution for the non-zero transverse single spin asymmetry of forward $\pi^{0}$ ($2 < \eta < 4$) was brought up. Bigger asymmetry was observed with more isolated final state which was connected with the non-perturbative event topology. Since the non-perturbative contribution...
Abstract In this talk we present our theoretical results for the multiplicity dependence of $J/\psi$ production and compare it with recent experimental data from STAR and ALICE collaborations. We argue that a rapidly growing multiplicity dependence presents a strong evidence in favor of multigluon fusion mechanisms of the quarkonia states. We demonstrate that the experimentally observed...
Latest results from the NA62 experiment at CERN.
The NA62 experiment at the CERN SPS is designed to measure the branching ratio of the K+→π+vv ̅ decay, one of the best candidates to reveal indirect effects of new physics at the highest mass scales with a very precisely predicted branching ratio of less than 10-10.
NA62 took data in 2016-2018.
Data statistics collected in 2016 allowed...
Central exclusive production at hadron colliders results in a hadronic state at or close to midrapidity, and forward scattered protons. The rapidity range between the midrapidity tracks and the forward scattered system is void of particles, thereby yielding a double gap topology which can be identified experimentally. At the high energies of the LHC, pomeron-pomeron fusion dominates the...
Following our recent Monte Carlo determination of the pion’s PDFs from Drell-Yan (DY) and leading neutron electroproduction data, we extend the analysis by including effects from threshold resummation. At higher orders in the strong coupling, $\alpha_S$, large logarithmic corrections due to soft gluon emissions become important in the $q\bar{q}$ channel near threshold, which can be summed over...
We present our recent results on the QCD evolution of the Jaffe-Manohar orbital angular momentum distributions. We discuss both $Q^2$ evolution and small-$x$ evolution.
The confinement of quarks and gluons, the building blocks of all visible matter, is perhaps the ultimate example of quantum entanglement. Inside nucleons they are not just correlated, they do not even exist as isolated states. However, in the parton model formulated by Bjorken, Feynman, and Gribov, the partons are viewed by an external hard probe as independent when the nucleon is boosted to...
In this talk, we will present recent results on ultra-peripheral heavy-ion collisions with the CMS detector. This will include measurements on vector meson photoproduction in ultra-peripheral pPb and PbPb collisions, as well as light-by-light scattering measurements, and new studies of exclusive processes in photon-induced interactions to study low-x QCD dynamics. In addition, recent results...
Latest results about searches for long-lived particles with the CMS experiments will be presented. Prospects for Run III and beyond will also be discussed.
The realisation of the LHeC and the FCC-eh at CERN require the development of the energy recovering technique in multipass mode and for large currents ${\cal O}(10)$ mA in the SRF cavities. For this purpose, a technology development facility, PERLE, is under design to be built at ICLab Orsay, which has the key LHeC ERL parameters, in terms of configuration, source, current, frequency and...
We discuss the impact of top-quark pair production data on the CT18 PDFs family.
In particular, we discuss the individual impacts of differential ttbar cross section measurements at 8 TeV collision energy from CMS and ATLAS which have been analyzed using different statistical frameworks (ePump and PDFSense) to assess their impact on PDFs before the global fit. We discuss tensions between...
Ultra-relativistic heavy ion collisions are expected to produce some of the strongest magnetic fields ($10^{13}-10^{16}$ Tesla) in the Universe[1].
These intense electromagnetic fields have been proposed as a source of linearly-polarized, quasi-real photons[2] that can interact via the Breit-Wheeler process to produce $e^+e^-$ pairs[3]. Demonstration that these photons are linearly polarized...
The Electron-Ion Collider will be the first collider to use both polarized electron beams and polarized proton and light ion beams. This will offer unique opportunities to study the structure of protons and nuclei and to answer fundamental questions in QCD.
The uncertainties on the polarization measurement translate directly into the uncertainties of final physics observables. Hence, a...
The production of prompt isolated photons and jets at hadron colliders provides stringent tests of perturbative QCD and can be used to evaluate the probability density functions of partons in the proton. In this talk, we present the measurements of the isolated-photon plus two jets and the inclusive isolated-photons cross sections, both measured using proton-proton collision data collected by...
Various theories beyond the Standard Model predict unique signatures which are difficult to reconstruct and for which estimating the background rates is also a challenge. Signatures from displaced decays anywhere from the inner detector to the muon spectrometer, as well as those of new particles with fractional or multiple values of the charge of the electron or high mass stable charged...
Deep Inelastic Scattering (DIS) and especially Semi-Inclusive Deep Inelastic Scattering (SIDIS) are leading processes in the study of hadron structure. The theoretical treatments of these processes involve approximations which only hold true in specific regions of kinematics, each region corresponding to a different physical picture. Ratios have been defined to be representative of terms which...
We develop a systematic treatment of heavy-flavor hadroproduction in the framework of the General-Mass Variable-Flavor-Number Scheme (GM-VFNS). By following the idea of the Simplified-ACOT-$\chi$ Scheme in Deep Inelastic Scattering (DIS), we categorize the open heavy-flavor diagrams into Flavor Excitation (FE) and Flavor Creation (FC) contributions. In order to avoid double counting,...
Rare and exotic decays of the Higgs boson provide a unique
window for the discovery of new physics, as the Higgs boson may couple to leptons in flavour violating or otherwise anomalous ways, or to hidden-sector states that do not interact under the Standard Model gauge transformations. This talk summarizes recent ATLAS searches for unexpected decays of the 125 GeV Higgs boson: enhanced...
We study the semi-inclusive production of hard, isolated photons in unpolarized and polarized lepton-proton collisions, i.e., $\ell p\to \ell\gamma X$. We analyze the transverse nucleon single-spin asymmetry within the collinear twist-3 formalism in perturbative QCD to leading order accuracy (LO). We find that this spin asymmetry is generated by twist-3 dynamical quark-gluon-quark ($qgq$)...
An important phenomenological consequence of the phenomenon of gluon saturation is the suppression of back-to-back hadron and jet pairs produced in the forward region of pA collisions. We present a new calculation of this process within the dilute-dense formalism of the color glass condensate (CGC) effective theory. Following Ref. [1], we collide a large-$x$, dilute probe, described in terms...
Over the past several years, parton distribution functions (PDFs) have become more precise. However there are still kinematic regions where more data are needed to help constrain global PDF extractions, such as the ratio of the sea quark distributions $\bar{d}$/$\bar{u}$ near the valence region. Furthermore, current measurements appear to suggest different high-$x$ behaviors of this ratio. The...
The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will enable a spectrum of new or improved cold QCD measurements. With its excellent tracking and full calorimetry (hadronic and electromagnetic) in the central pseudo-rapidity region, sPHENIX provides excellent opportunities for the studies of the partonic structure and dynamics in nucleons and nuclei. This includes the...
In order to perform precise Standard Model measurements or to search for new physics phenomena at hadron colliders, it is important to have a good understanding of not only the short-distance hard scattering process, but also of the accompanying activity – collectively termed the underlying event. In this talk we present a study of the underlying event activity in events containing a Z-boson...
The main focus of this talk is our recent work [1] on transverse single spin asymmetry (SSA) in semi-inclusive DIS in a collinear twist-3 framework. I will explicitly demonstrate that a genuinely new contribution containing the $g_T$ distribution function (alongside the kinematical and the dynamical Qiu-Sterman functions) is first seen at two loops. The phase required for a non-zero SSA from...
The presence of a non-baryonic dark matter (DM) component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model (SM) it could be produced at the LHC. The ATLAS experiment has developed a broad search program for DM candidates, including resonance searches for the mediator which would couple DM to the SM. The...
The interplay between the small x limit of QCD amplitudes and QCD factorization at moderate x has been studied extensively in recent years. It was finally shown that semiclassical formulations of small x physics can have the form of an infinite twist framework involving Transverse Momentum Dependent (TMD) distributions in the eikonal limit. In this work, we demonstrate that small x...
While significant steps toward the formal definition of quark TMDs and their extraction from experimental data through global fits has been made in the last years, the gluon-TMD field represents a largely unexplored territory. Pursuing the goal of extending our knowledge of this sector, we present analytic expressions for all $T$-even gluon TMDs at twist-2, calculated in a spectator model for...
The tremendous phenomenological success of the Standard Model (SM) suggests that its flavor structure and gauge interactions may not be arbitrary but should have a fundamental first-principle explanation. In this work, we explore how the basic distinctive properties of the SM dynamically emerge from a unified New Physics framework tying together both flavour physics and Grand Unified Theory...
The differential cross section measurements of the production of a pair of opposite-charged leptons as a function of pt and phi* in various bins of its invariant mass M are presented. The results are obtained using proton-proton collision data recorded with the CMS detector at the LHC. Measurements are also compared to state-of-the-art generators as well as TMD based predictions.
The scattering and neutrino detector (SND) at the LHC will measure for the first time neutrino properties from $pp\rightarrow \nu X$ and search for Dark Matter in an unexplored energy and pseudo-rapidity range. It will be located in the TI18 tunnel, which is ideal due to the low environmental and machine-induced background. The detector will measure the neutrino energy and identify all three...
Scattering amplitudes have always been essential to compute cross sections and production rates at colliders. In the last few years, though, there has been terrific progress in understanding the rich mathematical structure of scattering amplitudes, the more so in specific kinematic regions, like the Regge limit. In this talk, I will outline what we have learnt about the weak-coupling...
Two-particle azimuthal correlations have been measured in neutral current deep inelastic ep scattering with virtuality $Q^2 > 5$ GeV$^2$ at a centre-of-mass energy $\sqrt{s}=318$ GeV recorded with the ZEUS detector at HERA. The correlations of charged particles have been measured in the range of laboratory pseudorapidity $-1.5 < \eta < 2$ and transverse momentum $0.1 < p_T < 5$ GeV and event...
We propose an all-loop expression for scattering amplitudes in planar N=4 super Yang-Mills theory in multi-Regge kinematics valid for all multiplicities, all helicity configurations and arbitrary logarithmic accuracy. Our expression is arrived at from comparing explicit perturbative results with general expectations from the integrable structure of a closely related collinear limit. A crucial...
The leading-twist azimuthal asymmetries in the pion induced Drell-Yan process in the COMPASS kinematics are calculated considering any polarization of the proton target. The calculations are performed at tree level in the framework of TMD factorization using the predictions from the light front constituent model. The results are compared to the available COMPASS data, and predictions for not...
Tau neutrino properties are not well known in comparison to those of muon or electron neutrinos. The tau neutrino interaction cross-section is known with large uncertainties. In particular, measured by the DONuT experiment in 2008, it has about 30% statistical error and systematical error of about 50% due to a poor knowledge of the tau neutrino flux in this beam dump experiment. Precise...
The study of hadron production and anisotropic flow are key to the understanding of the medium produced in heavy ion collisions and its event-by-event fluctuations. Recent results in small systems both at RHIC and LHC support the formation of such medium at those scales.
PHENIX has measured the spectra of charged and identified particles for several small systems and at various energies, as...
Most recent results on searches for supersymmetric (SUSY) particles decaying to final states containing high energy photon(s) are presented. The searches are based on data collected at the center-of-mass energy of 13 TeV in proton-proton collisions recorded by the CMS detector. Photons may arise directly from a decay of a SUSY particle or due to the decay of a Higgs boson created in the SUSY...
We analyze the possibilities for the study of inclusive diffraction offered by future electron-proton/nucleus colliders in the tera-electron-volt regime, the Large Hadron-electron Collider (LHeC) as an upgrade of the HL-LHC, and the Future Circular Collider in electron-hadron mode. Compared to ep collisions at HERA, we find an extension of the available kinematic range in x by a factor of...
Transverse momentum dependent (TMD) parton distributions enter QCD factorisation formulas which include resummation and nonperturbative contributions to non-inclusive collider observables such as Drell-Yan differential cross sections. Recently, a parton branching (PB) formalism has been proposed for the evolution of TMDs, given in terms of Sudakov form factors and splitting functions. This...
In the context of the Physics Beyond Colliders initiative at CERN, the COMPASS++/AMBER proto-collaboration recently submitted a proposal to the SPSC in which a broad experimental programme of measurements at the M2 beam line of the CERN SPS is described. It addresses fundamental issues leading to significant improvements in our understanding of strong interactions in the medium and long-term...
Sivers function is a fundamental TMD which allows to investigate the 3D structure of polarized nucleons. We present a recent extraction of this function from azimuthal asymmetries in semi-inclusive DIS. This study includes for the first time TMD evolution contributions and a parametrization of unpolarized TMDs determined directly from data. Through this analysis we can obtain a tomography of...
ATLAS measurements of flow harmonics ($v_n$) and their fluctuations in Pb+Pb and Xe+Xe collisions covering a wide range of transverse momenta, pseudorapidity and collision centrality are presented. The measurements are performed using data from Xe+Xe collisions at 5.44 TeV and Pb+Pb collisions at 2.76 and 5.02 TeV. The $v_{n}$ are measured up to $n=6$ using the two-particle correlations,...
Many theories beyond the Standard Model predict new phenomena, such as Z’ and leptoquarks, in final states containing bottom or top quarks. Such final states offer great potential to reduce the Standard Model background, although with significant challenges in reconstructing and identifying the decay products and modelling the remaining background. The recent 13 TeV pp results, along with...
We compute DIS structure functions using off-shell matrix elements based on kT-factorization. The obtained results are used together with parton branching evolution and HERA data in order to fit unintegrated (transverse momentum dependent) parton distributions. This allows us to have a consistent framework where off-shellness of initial partons is treated both in parton evolution and in matrix...
Quantum tomography reconstructs higher dimensional features of quantum mechanical
systems from lower dimensional experimental information. The method is practical and directly processes experimental data while bypassing field-theoretic formalism. Quantum tomography can probe entanglement while avoiding model assumptions such as factorization. We review recent work applying quantum tomography...
The sPHENIX detector currently under construction at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) is designed to significantly advance studies of the microscopic nature of the Quark
Gluon Plasma. With a multi-year physics program beginning in 2023, sPHENIX employs state-of-the-art detector technologies and will fully exploit the highest planned RHIC luminosities. ...
This talk presents multiple recent ATLAS measurements form the ATLAS collaboration that study features of the azimuthal distributions for charged particles in $pp$ and $p$+Pb collisions. The measurement of the azimuthal anisotropy of charged hadrons in $p$+Pb collisions up to a transverse momentum of 50 GeV are presented. In A+A collisions non-zero flow coefficients at high-$p_{T}$ are...
Supersymmetry (SUSY) provides elegant solutions to several
problems in the Standard Model, and searches for SUSY particles are an important component of the LHC physics program. This talk will present the latest results from searches conducted by the ATLAS experiment, covering both strong and electroweak SUSY particle production processes. The searches target multiple final states and...
We present a new determination of Transverse Momentum Dependent (TMD) parton distributions obtained with the Parton Branching method. The PB TMDs are extracted from fits to precision DIS data using DGLAP splitting functions at leading and higher order.
In addition the fit sensitivity to dynamical resolution scales on TMD evolution in different kinematical region of x and Q2 will be investigated.
The Large Hadron Collider (LHC) has been successfully delivering proton-proton collision data at the unprecedented center of mass energy of 13 TeV. An upgrade is planned to increase the instantaneous luminosity delivered by LHC in what is called HL-LHC, aiming to deliver a total of about 3000/fb of data to the ATLAS detector at a center of mass energy of 14 TeV. To cope with the expected...
Nuclear and particle physics are both presently grappling with an array of fundamental questions, running from the dynamical origin of hadronic mass and spin on the one side, to high-energy tests of the Standard Model on the other. Given this situation, we expect a future DIS collider --- the Electron-Ion Collider (EIC) for which DOE recently announced CD-0 --- to play an essential role in...
The study of QCD has served as a unifying focus and a common ground for the disciplines of high-energy and nuclear physics, and for both phenomenological and formal studies in theoretical physics. We are embarking on a historic journey. Existing facilities, from JLab to the LHC, and the now-approved Electron-Ion Collider, will provide unprecedented opportunities and challenges to reach a...
We present a first measurement of two-particle angular correlations for charged hadrons emitted from photon-proton, $\gamma p$, interactions over a wide range of pseudorapidity and full azimuth. The $\gamma p$ events were produced within ultra-peripheral pPb collisions at $\sqrt{s_{NN}}$ = 8.16 TeV and were selected by requiring a large rapidity gap in the lead-going direction and no neutron...
Future high luminosity experiments, such as sPHENIX or any EIC detector, will greatly benefit from the use of a Time Projection Chamber (TPC) as one of its main tracking systems. A TPC’s ability to measure space points of charged tracks makes it an excellent detector for the desired resolution in momentum and energy loss dE/dx. The resolution is limited by distortions from Space Charge (SC) in...
There is a nationwide drive to get more girls into physics and coding, and some educators believe gaming could be a way to get girls interested in coding and STEM topics. This project, sponsored by NSF, is to create a Quantum Chromodynamics (QCD) game that will raise public interest in QCD, especially among K-12 girls, and increase interest in coding among girls. Through the immersive...
In this talk, we will present recent results on ultra-peripheral heavy-ion collisions with the CMS detector. This will include measurements on vector meson photoproduction in ultra-peripheral pPb and PbPb collisions, as well as light-by-light scattering measurements, and new studies of exclusive processes in photon-induced interactions to study low-x QCD dynamics.
We investigate the forward-jet energy spectrum within the color glass condensate framework at 5 TeV center-of-mass energy. In particular, we focus on the kinematic range covered by the CMS-CASTOR calorimeter. We show that our saturation-model calculations are compatible with the CASTOR measurements and that to optimally reproduce the data, effects of multiparton interactions need to be...
We will present results on the nucleon spin decomposition and the momentum distribution among quarks in the nucleon. Techniques for lattice QCD simulations at the physical pion mass applied for the computation of sea-quark and gluon contributions will be presented. We will discuss several challenges and perspectives for future developments.
The STAR Collaboration is constructing a forward rapidity (2.5 < $\eta$ < 4) upgrade that will include charged particle tracking and electromagnetic/hadronic calorimetry. Charge particle tracking capabilities are achieved via a combination of silicon detectors and small strip thin gap chamber detectors. Combining these detector types to achive tracking in the STAR forward region poses unique...
