The turn-on of high energy hadron colliders, such as RHIC and the LHC, have created a new arena for the study of TMDs. The collisions of protons over a wide range of center-of-mass energies allow for tests of universality and factorization as well as the study of evolution effects. The wide-acceptance and variety of technologies featured in typical collider detectors have paved the way for...
In this talk, I will summarize the TMDs from the Collins-Soper-Sterman Resummation formalism. Phenomenological results from recent global analysis of ResBos approach will also be presented, including the TMDs and the associated Collins-Soper evolution kernel.
We present a global extraction of unpolarized Transverse Momentum Dependent (TMD) Parton Distribution Functions (PDFs) and Fragmentation Functions (FFs) from two different types of processes: Semi-Inclusive Deep Inelastic Scattering (SIDIS) and Drell–Yan (DY). The analysis is performed in the TMD factorization framework and is based on data from several experiments and kinematic ranges.
The...
I will present our work, https://inspirehep.net/literature/2628962, on the first simultaneous extraction of parton collinear and transverse degrees of freedom from low-energy fixed-target Drell-Yan data in order to compare the transverse momentum dependent (TMD) parton distribution functions (PDFs) of the pion and proton. We demonstrate that the transverse separation of the quark field encoded...
Semi inclusive deep inelastic scattering is a well established tool to study TMDs and fragmentation functions. With the CLAS12 detector at Jefferson Laboratory (JLab) precise, multidimensional measurements of cross sections and asymmetry observables become possible in the valence quark regime, for the first time.
As a first observable, the structure function ratio $F_{LU}^{\sin\phi}/F_{UU}$...
We propose an observable $q_*$ sensitive to transverse momentum dependence (TMD) in
$e N \to e h X$, with $q_*/E_N$ defined purely by lab-frame angles. In 3D measurements of confinement and hadronization this resolves the crippling issue of accurately reconstructing small transverse momentum $P_{hT}$. We prove factorization for $\mathrm{d} \sigma_h / \mathrm{d}q_*$ for $q_*\ll Q$ with...
We present an updated analysis of Belle data for the transverse $\Lambda$ polarization in $e^+e^−$ annihilation processes within a TMD factorization approach. $SU(2)$ isospin symmetry and charm quark contribution, with their impact on the description of the experimental data as well as on the extraction of the polarizing fragmentation functions, will be discussed.
Predictions for SIDIS...
In this talk we will provide a survey of three fundamental objects: quasi-TMDPDF, quasi-LFWF amplitudes and (quark non-singlet) quasi-PDF matching kernel that appears naturally in the application of LaMET to lattice calculation of various parton distribution functions. We demonstrate how TMD factorization or threshold factorization works for the corresponding objects with a common perturbative...
I review the latest progress in the determination of Collins-Soper kernel. There are two main subjects to be discussed. The first one is the recent N4LL global analysis of the Drell-Yan data, which provides a very precise control of the evolution due a huge span of energies (from 4 GeV to 1000 GeV). The second one is the determination of the Collins-Soper kernel from the twist-three TMD distributions.
We present a first calculation of the unpolarized proton’s isovector transverse-momentumdependent parton distribution functions (TMDPDFs) from lattice QCD, which are essential to predict observables of multi-scale, semi-inclusive processes in the standard model. We use a Nf = 2 + 1 + 1 MILC ensemble with valence clover fermions on a highly improved staggered quark sea (HISQ) to compute the...
The status of an ongoing program of evaluating TMD observables
within Lattice QCD is reviewed. These lattice calculations are
based on a definition of TMDs through hadronic matrix elements
of quark bilocal operators containing staple-shaped gauge
connections. A parametrization of the matrix elements in terms
of invariant amplitudes serves to cast them in the Lorentz frame
preferred for a...
This work presents a determination of the quark Collins-Soper kernel, which relates transverse-momentum-dependent parton distributions (TMDs) at different rapidity scales, using lattice Quantum Chromodynamics (QCD). This is the first lattice QCD calculation of the kernel at quark masses corresponding to a close-to-physical value of the pion mass, with next-to-next-leading order matching to...
Generalized parton distributions (GPDs) are important quantities that characterize the 3-D structure of hadrons, and complement the information extracted from TMDs. They provide information about the partons’ momentum distribution and also on their distribution in position space. Most of the information from lattice QCD is on the Mellin moments of GPDs, namely form factors and their...
We report an ongoing analysis of the lattice-QCD calculation of the isovector quark transversity distribution of the proton at physical pion mass at lattice spacing 0.06~fm using large-momentum effective theory. We compare our results with previous lattice calculations and discuss potential synergies with global analysis.
I will report on a recent QCD global analysis of single-spin asymmetries involving observables where single-hadron fragmentation is relevant. This includes measurements of the Sivers, Collins, and \sin(\phi_S) effects in SIDIS, Collins effect in electron-positron annihilation, Sivers effect in Drell-Yan, and AN in single-inclusive proton-proton collisions, which are sensitive to important TMD...
We propose a new definition of unintegrated dihadron fragmentation functions (DiFFs) which is compatible with the probability interpretation of collinear DiFFs and derive the leading-order evolution equations for these DiFFs. With these new definitions, we perform the first simultaneous extraction of DiFFs and transversity PDFs using data from semi-inclusive annihilation (SIA) in...
Two-particle azimuthal correlations provide valuable insights into the dynamics of gluon saturation in collider experiments. In the kinematic regime where the two particles are produced sufficiently forward in rapidity but back-to-back in the transverse plane, the differential cross-section computed in the Color Glass Condensate (CGC) EFT, admits a small-x Transverse Momentum Dependent (TMD)...
We propose semi-inclusive
diffractive deep inelastic scattering (SIDDIS) to investigate the gluon tomography in the nucleon and
nuclei at small-x. The relevant diffractive quark and gluon parton distribution functions (DPDF) are computed in terms of the color dipole S-matrices in the fundamental and adjoint representations. respectively.
Typically, a production of a particle with a small transverse momentum in hadron-hadron collisions is described
by CSS-based TMD factorization at moderate Bjorken $x_B\sim 1$ and by $k_T$-factorization at small $x_B$.
A uniform description valid for all $x_B$ is provided by rapidity-only TMD factorization developed in a series
of recent papers. In this talk, I will discuss two applications:...
Resolution of the proton spin puzzle, which is inability of the constituent quark model to explain discrepancy between the spin-$1/2$ of the proton and the amount of spin carried by its quarks and gluons, as measured in experiment, is an outstanding problem in modern hadronic physics. One possibility is that ‘’missing” spin of the proton may be found at small values of Bjorken-x. I’ll give an...
We initiate the study of transverse momentum-dependent (TMD) fragmentation functions for heavy quarks, demonstrate their factorization in terms of novel nonperturbative matrix elements in heavy-quark effective theory (HQET), and prove new TMD sum rules that arise from heavy-quark spin symmetry. We discuss the phenomenology of heavy-quark TMD FFs at $B$ factories and find that the Collins...
