LoopFest XXIV

27 May 2026, 00:00 → 29 May 2026, 17:00 US/Eastern

Physics Department (Bldg. 510), Large Seminar Room (Brookhaven National Laboratory)

LoopFest 2026 will provide a forum for discussing the latest results in precision quantum field theory and their applications to experimental results and projections for future colliders.

Topics Include:

• The potential of the LHC and future e+e- colliders for precision measurements
• Progress in multi-loop and multi-leg calculations
• Applications of effective field theory techniques to precision calculations

 

Go back to Main Website


Confirmed Speakers include:

Samuel Abreu	Giulio Gambuti	Ian Moult
Supratim Das Bakshi	Peter Vander Griend	Christoph Nega
Piotr Bargiela	Marco Guzzi	Tobias Neumann
Riccardo Bartocci	Valentin Hirschi	Fredrick Olness
Luigi Bellafronte	Timothy J. Hobbs	Rudi Rahn
Federico Buccioni	Stefan Hoeche	Laura Reina
Emmet Byrne	Sebastian Jaskiewicz	Jurgen Reuter
Zeno Capatti	Max Knobbe	Felix Ringer
Sergio Carrolo	Manfred Kraus	Farid Salazar
Herschel Chawdhry	Rebecca Von Kuk	Marvin Schnubel
Christoph Dlapa	Juhun Kwak	Giovanni Stagnitto
Gabriele Fiore	Kyle Lee	Adi Suresh
Duarte Fontes	Martin Link	Davide Maria Tagliabue
Matthew Forslund	Cesare Mella	Francesco Ucci
Ayres Freitas	Sebastian Mizera	Shun-Qing Zhang
Daniele Gaggero	Jake Montgomery	Xiaoyuan Zhang

 

Event ID: B000007355

Wednesday 27 May

Opening Session

Convener: Sally Dawson (BNL)

1 Welcome

Speaker: Sally Dawson (BNL)

welcome.pdf

2 Resurrecting LEP

Speaker: Ian Moult

IanMoult_Brookhaven_2026.pdf

3 Heavy Quark Effects in Soft-Collinear Effective Theory

Speaker: Rebecca von Kuk (Bern)

LoopFest2026_RvK.pdf

4 Local Unitarity and numerical perturbative QFT in momentum-space

Speaker: Valentin Hirschl (CERN)

LoopFest_Brookhaven.pdf

10:30 Coffee Break

Plenary Session 2

Convener: Ciaran Williams (SUNY Buffalo)

5 Two-Loop Spacelike Splitting Amplitudes for QCD in Full Color

Speaker: Federico Buccioni (CERN)

buccioni_LF_XXIV.pdf

6 The Charm of Charged Currents: Massive DIS at NNLO

Speaker: Martin Link

loopfest_slides_Link.pdf

7 The Alaric Project

Speaker: Stefan Hoeche (Fermilab)

12:30 Lunch

Plenary Session 3

Convener: Laura Reina (Florida State University)

8 The Fermi Function, Factorization and the Neutron’s Lifetime

Speaker: Peter Vander Grierd (Kentucky)

vander_grierd_loopfest2026.pdf

9 Three-loop rapidity anomalous dimension and N3LL resummation of jet-vetoed Higgs cross sections

Speaker: Samuel Abreu

abreu.pdf

10 Climbing the Spin Tower: Spinning Black Holes from Fixed-Spin Theories

Speaker: MANFRED KRAUS (IF-UNAM)

mkraus.pdf

15:30 Coffee

Parallel Session a

Convener: Federico Buccioni (CERN)

11 Factorization and Resummation for PDFs at threshold

We study factorization at next-to-leading power (NLP) in deep inelastic scattering (DIS) in the endpoint region within the framework of soft-collinear effective theory (SCET). The full QCD process is matched onto two SCET currents, whose matrix elements factorize into individual component functions. By employing endpoint reshuffling theorems that relate these component functions at endpoint kinematics, we remove all endpoint divergences. We then derive the relevant renormalization-group (RG) equations and solve them at leading order in RG-improved perturbation theory, thereby resumming large logarithms to all orders. Our main finding is that, in the endpoint limit, new structures emerge for the parton distribution functions (PDFs). We argue that a non-minimal subtration scheme is well-suited to subtract both UV and endpoint divergences at the same time.

Speaker: Marvin Schnubel (Nikhef)

LoopFest26_MSchnubel.pdf

12 The KLN theorem meets collinear factorisation

The KLN theorem establishes that infrared divergences in parton‑model diagrams cancel when summed alongside diagrams that account for the simultaneous hard interaction of multiple partons within the same hadron. Meanwhile, it is well established that initial-state infrared poles and logarithms are governed by collinear factorisation. In this talk, I introduce a formalism where an initial-state implementation of KLN works hand in hand with collinear factorisation.
I will show that in this framework hadronic cross-sections can be expressed in terms of iterated discontinuities of Feynman diagrams and expanded in virtuality using standard expansion-by-regions techniques. The leading virtuality contribution will be shown to be equivalent to the MSbar parton model result through a universal scheme change. In turn, this enables the application of the Local Unitarity method to the computation of hadronic cross sections.

Speaker: Zeno Capatti (University of Bern)

Loopfest_talk_Capatti.pdf

13 Collinear limits of multi-leg scattering amplitudes

Scattering amplitudes are expected to admit a factorised structure in specific kinematic limits, such as the Regge, soft and collinear limits. However, less is known about the precise mechanisms through which factorisation of n-particle amplitudes is realised at high perturbative orders, where more complex colour and kinematic structures arise. Starting with the soft anomalous dimension, in this talk I will discuss the multi-particle collinear limits of massless amplitudes at three- and four-loop orders. In particular, I will show how strict collinear factorisation of multiple massless final-state coloured particles is achieved, and demonstrate that the conditions on the structure of the soft anomalous dimension required by two-particle collinear limits are sufficient to guarantee factorisation also in any multiple collinear limit. I will also discuss new constraints on the soft anomalous dimension that arise from multi-collinear limits for amplitudes containing massive coloured particles.

Speaker: Sebastian Jaskiewicz

LoopFest26-multi-collinear-limits-jaskiewicz.pdf

14 Automated Calculation of Soft Functions for Non-global Observables

The analytic resummation of non-global logarithms is more involved than resummation in the global case, it for example involves intricate factorisation theorems with ingredient functions of arbitrary final state hard multiplicities. In addition, disparate treatment of distinct emissions allows for a larger set of functional dependences in non-global observables. In this talk I will present progress towards automating the calculation of soft functions for non-global observables to second order in the strong coupling constant, with special focus on a path towards a public code for the calculation of such soft functions.

Speaker: Rudi Rahn (University of Amsterdam)

Loopfest_Rahn.pdf

15 Magic Relations and Critical Varieties of Feynman Integrals

Magic relations are a class of integration-by-parts identities that are generated in a sector which does not itself appear in the identity. They are of particular interest because their presence causes several otherwise successful methods in the Feynman-integral computational pipeline to break down. In this talk, we present a first step toward a systematic characterisation of such identities. In particular we discuss methods and algorithms for detecting and computing magic relations, which we find are deeply connected to the critical point varieties produced by Feynman integrals.

Speaker: Giulio Crisanti

loopfest_presentation_split.pdf

16 An Analytic Regression Path to Precision QCD

In precision studies of QCD, obtaining exact analytic expressions for physical observables is important for both phenomenological predictions and uncovering theoretical structure, yet is often hindered by the complexity of Feynman integrals. While perturbative bootstrap programs have achieved remarkable success for scattering amplitudes in theories like N=4 super Yang-Mills, their extension to QCD has remained challenging. We develop a hybrid framework that applies bootstrap principles to QCD observables by combining analytic constraints with numerical data. In particular, we employ analytic regression with lattice reduction, a technique that reconstructs exact rational coefficients by fitting a functional ansatz to high-precision numerical samples. As a first example, we apply this method to energy correlators in the multi-collinear limit, taking a concrete step toward an analytic bootstrap for precision QCD.

Speaker: Xiaoyuan Zhang (MIT)

LoopFest2026.pdf

Parallel Session b

Convener: Ayres Freitas (University of Pittsburgh)

Bartocci_LoopFest.pdf

17 Including Dimension-8 Effects in SMEFT: Renormalization, and Phenomenology

Recent studies in the Standard Model Effective Field Theory (SMEFT) highlight the importance of consistently retaining terms of order O(1/$\Lambda^4$) in theoretical predictions. In this presentation, we analyze SMEFT at O(1/$\Lambda^4$), including 1-loop renormalization group evolution (RGE) effects arising from the scale dependence of Wilson coefficients, with explicit incorporation of dimension-8 operators. We review the current status of dimension-8 renormalization and summarize recent progress in the computation of SMEFT RGEs. Finally, we investigate the phenomenological impact of Wilson-coefficient running within both a bottom-up EFT framework and a model-dependent top-down approach.

Speaker: Supratim Das Bakshi (Argonne National Laboratory)

Supratim+Brookhaven+May27.pdf

18 Higgs Production via Gluon Fusion in the SMEFT at Next-to-Leading Order

Gluon-gluon fusion is the dominant channel for Higgs production at the Large Hadron Collider (LHC) and will remain a key probe of Higgs interactions at the High-Luminosity LHC, where improved experimental precision will require equally precise theoretical predictions. In this talk we focus on Higgs production via gluon-gluon fusion within the Standard Model Effective Field Theory (SMEFT) at NLO, including two-loop corrections computed using both analytic and numerical techniques. The calculation considers the full set of dimension-six operators contributing to the $gg \to h$ amplitude.

The analysis includes a phenomenological study of the SMEFT coefficients, with particular emphasis on the operator $C_{\phi G}$, which gives large contributions to the cross section. The results are compared with existing approaches in the literature, as well as with bounds obtained from global-fit analyses.

Speaker: Luigi Bellafronte (Florida State University)

BNL_seminar.pdf

19 Parity-Violating Moller Scattering at NNLO: Electroweak bosonic contribution

We present the analytic computation of the two-loop electroweak bosonic correction to the parity asymmetry in Moller scattering at low energy. The hierarchy of scales, namely $m_Z^2\gg q^2\gg m_e^2$, and the IR singularities are treated with the method of regions. We discuss the implications of our results to MOLLER at JLab and give an outlook for electron-proton and electron-nucleus scattering at P2.

Speaker: Juhun Kwak (University of Pittsburgh)

J.Kwak_PVES@EWNNLO.pdf

20 Electroweak corrections to gg → γγ

Since the discovery of the Higgs boson at LHC, particle physics has entered a new precision era in which improving the accuracy of Standard Model predictions is essential for testing the theory and uncovering potential hints of new physics. In this context, diphoton production plays an important role, both as a probe of the Standard Model and as a background for Higgs measurements. As theoretical and experimental precision continue to improve, electroweak effects become increasingly relevant. In this talk, I will present our calculation of the electroweak corrections to diphoton production through gluon fusion, focusing on the contributions arising from the first two quark generations. The two-loop amplitude is computed using a combination of analytic and semi-numerical methods, allowing us to efficiently handle the most challenging parts of the calculation. I will present numerical results relevant for the LHC, where electroweak effects modify the leading-order gg→γγ cross section by a few percent. These results have been implemented in the parton-level Monte Carlo program MCFM, enabling their use in phenomenological studies.

Speaker: Gabriele Fiore (ETH Zurich)

Loopfest2026_GF.pdf

21 NLO corrections to inclusive $\bar{B} \to X_s \gamma$ decays at subleading power

Theoretical predictions in hadron physics are often limited by non-perturbative uncertainties in QCD. Nevertheless, several phenomenologically important processes require improved theoretical control. Effective field theories, such as Soft-Collinear Effective Theory (SCET) and Heavy Quark Effective Theory (HQET), provide powerful tools to overcome these limitations by exploiting factorisation.
A particularly interesting class of observables arises in flavour physics, and in particular in inclusive $\bar{B} \to X_s \gamma$ decays. Among the resolved contributions to this process, the dominant theoretical uncertainty currently originates from the interference between the WET operators $O_1$ and $O_7$, which corresponds to non-local subleading power corrections.
In this work, we derive a factorisation formula for the $O_1$--$O_7$ interference that is suitable for the inclusion of perturbative $\alpha_s$ corrections. The factorised expression involves four distinct functions. We present explicit results for all of them, with particular emphasis on the renormalisation-group evolution of the shape function $g_{17}$, a generalised light-cone distribution amplitude depending on both light-cone directions, and the two-loop penguin jet function, which was computed fully analytically.
These ingredients complete the $\mathcal{O}(\alpha_s)$ corrections to the $O_1$--$O_7$ interference. Moreover, they provide important insight into the technical structure of these higher-order corrections. These results are expected to be highly relevant for future precision studies at subleading power.

Speaker: Riccardo Bartocci (Karlsruhe Institute of Technology (KIT))

Bartocci_LoopFest.pdf

22 A perturbative framework to probe IR sensitivity in non-Abelian gauge theories

Infrared sensitivity in asymptotically free non-abelian gauge theories is intimately connected to non-perturbative effects in processes with large momentum transfer. In the renormalon framework, such effects are probed by introducing a small gluon mass. Yet this procedure breaks gauge invariance, effectively restricting collider applications to reactions without gluons at Born level. In this talk, I present a gauge-invariant framework in which gluons acquire a small mass via the Higgs mechanism. I compute the heavy-quark pole–$\overline{{\rm MS}}$ mass relation through $\mathcal{O}(\alpha_s^2)$, providing a controlled laboratory to study infrared sensitivity in genuinely non-abelian processes.

Speaker: Duarte Fontes

Presentation.pdf

Thursday 28 May

PDFs

Convener: Clara Lavinia Del Pio (Brookhaven National Laboratory)

23 Precision matching kernels for lattice PDFs and TMDs in the HL-LHC era

Speaker: Tobias Neumann (SMU)

Neumann_Tobias.pdf

24 Precision QCD and Nuclear Structure: Toward the EIC with Precision nPDFs

Speaker: Fredrick Olness (SMU)

Olness_Loopfest_2026.pdf

25 Higher order corrections and PDF determinations

We discuss important aspects of global PDF analyses beyond NNLO in QCD with emphasis on the impact of recent higher-order calculations that are part of the ingredients of recent approximate N^3LO PDF determinations. In particular, we discuss the role of heavy-quark mass treatments and DGLAP evolution at N^3LO in QCD.

Speaker: Marco Guzzi (Kennesaw)

LoopFest2026-MGuzzi.pdf

10:25 Coffee Break

Jets and PDFs

Convener: Fredrick Olness (SMU)

26 PDFs at the precision frontier: collider phenomenology and jet physics

Speaker: Tim Hobbs (Argonne National Laboratory)

Hobbs_LoopFest_26.pdf

27 Jet physics at higher perturbative orders

Speaker: Giovanni Stagnitto (Milan)

stagnitto.pdf

28 Conformal Colliders Meet the LHC

Speaker: Kyle Lee (ANL)

Loopfest_KyleLee.pdf

12:30 Lunch

Parallel Session c

Convener: Sebastian Jaskiewicz

29 The spectrum of Feynman-integral geometries at two loops

In this talk, I will present the results of our recent paper arXiv:2512.13794 for a complete classification of the Feynman-integral geometries at two-loop order in four-dimensional Quantum Field Theory with standard quadratic propagators. Concretely, we consider a finite basis of integrals in the ’t Hooft–Veltman scheme, i.e. with D-dimensional loop momenta and four-dimensional external momenta, which belong to 79 independent topologies, or sectors. Then, we analyze the leading singularities of the integrals in those sectors for generic values of the masses and momenta, using the loop-by-loop Baikov representation. Aside from the Riemann sphere, we find that elliptic curves, hyperelliptic curves of genus 2 and 3 as well as K3 surfaces occur. Moreover, we find a smooth and non-degenerate Del Pezzo surface of degree 2, a particular Fano variety known to be rationalizable, resulting in a curve of geometric genus 3. These geometries determine the space of functions relevant for Quantum Field Theories at two-loop order, including in the Standard Model.

Speaker: Piotr Bargiela (The University of Edinburgh)

slides.pdf

30 Tropical Integration for Gauge Theory Feynman Integrals

I will present recent progress in extending the tropical integration framework originally proposed by Borinsky to Feynman integrals with numerators. This generalisation is essential for applications in gauge theories and significantly broadens the scope of tropical Monte Carlo methods to physically relevant observables in Quantum Chromodynamics (QCD) and N=4 super Yang–Mills theory (SYM).

I will introduce the extended tropical integration framework and a corresponding numerical implementation, which will be made publicly available. As a key benchmark, I will demonstrate the numerical evaluation of high-loop integrals arising in correlation functions of N=4 SYM, including the integrated correlator verified up to eight loops—far beyond the reach of existing analytic techniques.

In addition, the method has been tested on a variety of phenomenologically relevant QCD integrals involving multiple external legs, internal masses, and non-trivial numerators. In all cases, we find excellent agreement with established numerical tools such as pySecDec, while achieving substantially improved performance.

Speaker: Shun-Qing Zhang (Max Planck Institute for Physics)

LoopFest_Zhang.pdf

31 On Leading Singularities and Canonical Bases beyond Polylogarithms

Feynman integrals associated with geometries beyond the Riemann sphere, such as elliptic curves, K3 surfaces, and Calabi-Yau manifolds, are playing an increasingly important role in modern precision calculations, from collider physics to gravitational-wave theory. A systematic way to evaluate these integrals is through differential equations, with the goal of casting them into
epsilon-form, where their analytic behaviour and transcendental structure become more transparent.
In this talk, I will discuss the connection between leading singularities and canonical bases for Feynman integrals beyond the realm of multiple polylogarithms. In particular, I will show how the transcendental functions needed to describe the differential equation matrix of a canonical system can be identified directly from the integrand. The discussion will be illustrated through examples of increasing complexity involving the interplay of several geometries, including elliptic curves, K3 surfaces, and Calabi-Yau threefolds.

Speaker: Cesare Mella

loopfest_2026.pdf

32 Calabi-Yau Periods in Black Hole Scattering at the Fifth Post-Minkowskian Order

In recent years, it has been observed that period integrals of Calabi-Yau manifolds, which originate from the compactification of string theory, appear in the classical scattering of black holes. These mathematical structures were observed for the first time at the fifth post-Minkowskian (5PM) order. In my talk, I will provide a brief introduction to these objects, particularly from a practitioner’s perspective, and explain how they arise in the two-body problem of general relativity. Additionally, I will discuss our recent computations in the conservative sector at 5PM. Specifically, I will demonstrate that by analyzing canonical differential equations, we can understand the analyticity structure of the scattering angle, which in turn will constrain the boundary constants in our problem.

Speaker: Christoph Nega (employee@tum.de;member@tum.de;faculty@tum.de;alum@tum.de)

LoopFest.pdf

Parallel Session d

Convener: Juergen Reuter (DESY Theory Group)

33 Color coherent subtraction at NNLO QCD - The double-real case

Precision QCD calculations are essential for exploiting the physics potential of future high-luminosity lepton colliders such as the FCC-ee. We present a new local infrared subtraction scheme for next-to-next-to-leading order (NNLO) QCD calculations. The method employs scalar multipole radiator functions and pure splitting remainders that are fully color and spin dependent, valid across the complete phase space. Overlapping singularities in multipole radiators are systematically disentangled through partial fractioning, guided by coherent branching techniques. Numerical results for the double-real correction to e⁺e⁻ $\to$ 2j at the Z pole are presented.

Speaker: Max Knobbe

loopfest_2026_knobbe.pdf

34 Integrated subtraction terms and finite remainders for arbitrary massless QCD processes with jets at colliders using the nested soft-collinear subtraction scheme

The computation of higher-order corrections in QCD is complicated by infrared singularities, which must be isolated and cancelled to obtain a finite result.
I will present recent progress on the nested soft-collinear subtraction scheme, which provides a fully local and analytic subtraction for any QCD process with massless quarks and an arbitrary number of jets in the final state.

Speaker: Davide Maria Tagliabue (KIT - TTP)

LoopFestXXIV_2026 .pdf

35 On the local IR structure of scattering amplitudes

In this talk I will review recent progress in our understanding of infrared (IR) factorisation of scattering amplitude integrands. I will discuss how a detailed picture of the IR properties of gauge-theory scattering amplitudes can be exploited to derive finite-remainder integrands which are amenable to direct numerical integration, bypassing the complexity encountered in standard analytic calculations. As a proof of concept, I will use two-loop amplitudes in massless QED, where integrand-level finite remainders are known for generic processes. Finally, I will discuss generalisations to QCD, in particular the first steps towards a systematic understanding of the non-trivial interplay of colour flow, loop-momentum bases and the factorisation of collinear divergences.

Speaker: Giulio Gambuti (ETH Zurich)

slides_gg.pdf

36 Taking the First Step Toward the Higgs at N4LO in QCD: the Single-real Ingredient

We present partonic contributions to the inclusive gluon-fusion Higgs boson and Drell-Yan production cross sections at Hadron colliders at next-to-next-to-next-to-next-to leading order (N4LO). Specifically, we compute the “single-real” contributions: the interference of one-loop with two-loop amplitudes and the interference of three-loop (in the generalized leading-color limit) with tree-level amplitudes, consisting of three QCD partons and the Higgs boson or a virtual photon. Our result is in the form of a Laurent expansion in the dimensional regulator ϵ, the coefficients of which are analytic functions in the ratio of the Higgs boson or virtual photon mass to the partonic center of mass energy. Furthermore, we introduce and deploy a new package implemented in Mathematica, CIFAR ("Color Invariant Feynman Amplitude Reducer"), to express color factors in terms of general Casimir invariants of simple compact Lie algebras.

Speaker: Adi Suresh (SLAC)

LoopFest2026_AdiSuresh.pdf

15:30 Coffee

Parallel Session e

Convener: Yoshitaka Hatta (BNL)

37 Extracting Meson Distribution Amplitudes from Nonlocal Euclidean Correlations at Next-to-Next-to-Leading Order

Light-cone distribution amplitudes (DAs) describe the longitudinal momentum structure of quarks inside mesons and play a central role in exclusive QCD processes and precision flavor physics. As intrinsically non-perturbative quantities, their reliable determination from first principles has long been a major challenge.
In this talk, I will review recent progress in extracting light meson DAs from lattice QCD within the LaMET framework. I will present the first complete NNLO matching kernel and discuss its numerical impact in reducing perturbative uncertainties and improving the precision of lattice determinations.

Speaker: Fei Yao

Loopfest_Fei.pdf

38 Quasi-PDFs and quasi-GPDs in the massive Schwinger model using tensor networks

Generalized Parton Distribution functions (GPDs) are off-diagonal light-cone matrix elements that encode the internal structure of hadrons in terms of quark and gluon degrees of freedom. In this work, we present a nonperturbative study of quasi-PDFs and quasi-GPDs in the massive Schwinger model, quantum electrodynamics in 1+1 dimensions (QED2), within the Hamiltonian formulation of lattice field theory. Quasi-distributions are spatial correlation functions of boosted states, which approach the relevant light-cone distributions in the luminal limit. Using tensor networks, we prepare the first excited state in the strongly coupled regime and boost it to close to the light-cone on lattices of up to 400 lattice sites. We compute both quasi-parton distribution functions and, for the first time, quasi-GPDs, and study their convergence for increasingly boosted states. In addition, we perform analytic calculations of GPDs in the two-particle Fock-space approximation and in the Reggeized limit, providing qualitative benchmarks for the tensor network results. Our analysis establishes computational benchmarks for accessing partonic observables in low-dimensional gauge theories, offering a starting point for future extensions to higher dimensions, non-Abelian theories, and quantum simulations.

Speaker: Jake Montgomery (Stony Brook University)

LoopFestXXVI_PDFs 2.pdf

LoopFestXXVI_PDFs.key

39 Loops in Dense Fields: Precision QCD in the Color Glass Condensate

The Color Glass Condensate (CGC) describes QCD at very high energies, where gluons inside hadrons form a dense state that can be treated as a strong classical color field. In this regime, loop calculations differ significantly from the familiar perturbative expansion around the vacuum: quantum fluctuations propagate through a background field, Wilson lines become the relevant degrees of freedom, and large logarithms of energy must be resummed.

In this talk I will give a brief overview of how loop corrections are computed in the presence of such dense fields. After introducing the basic framework, I will discuss the structure of nonlinear rapidity evolution equations, as well as recent progress at next-to-leading order for selected observables.

Speaker: Farid Salazar (Temple University / Brookhaven National Lab)

LoopFest-CGC.pdf

40 Bootstrapping QCD amplitudes

In this talk, we present a framework for computing the maximally transcendental part of planar QCD scattering amplitudes. By analyzing the maximal-weight projection of amplitudes at the integrand level, we relate these contributions to prescriptive unitarity integrals and uncover a novel analytic structure: the rational prefactors multiplying functions of maximal transcendental weight coincide with the four-dimensional leading singularities of the theory. This observation implies that the pre-factors admit a complete classification and can be systematically computed using on-shell methods. As an application, we determine the two-loop pre-factors for planar MHV gluon amplitudes at arbitrary multiplicity. Combining these results with the known six-point function space, we bootstrap the symbol of the two-loop six-gluon MHV amplitude in QCD in the planar limit.

Speaker: Sergio Carrolo (Max Planck Institute For Physics)

Loopfest_Sergio.pdf

Parallel Session f

Convener: Tobias Neumann (SMU)

41 Streamlining canonical differential equations through factorized Picard-Fuchs operators

The method of differential equations has become one of the most powerful tools for the evaluation of multiloop Feynman integrals. In recent years, substantial progress has been made in extending the notion of canonical differential equations beyond the multiple polylogarithm case to integrals involving more general geometries. Nevertheless, deriving canonical forms for such systems remains challenging and often requires significant case-by-case insight.

In this talk, I present a new algorithm—soon to be published—for systematically deriving canonical differential equations for Feynman integrals, irrespective of the underlying geometry. The approach combines several recent conceptual and algorithmic developments with new techniques that allow one to efficiently identify suitable bases and canonicalize the associated differential systems. The algorithm is constructive and well suited for practical computations.

I will demonstrate the method on a range of nontrivial examples, showing how it produces canonical differential equations for integrals that go beyond the polylogarithmic class in a largely automated, black-box fashion. These results provide further evidence that the canonical differential equation framework can be extended in a systematic way to broader classes of Feynman integrals and represent an important milestone toward streamlining future multiloop calculations relevant for precision collider physics.

Speaker: Christoph Dlapa (University of Hamburg)

Loopfest_2026_singleslide.pdf

42 Advances in quantum computation of perturbative QFT scattering

Perturbative QFT calculations can pose considerable computational challenges at higher orders and higher multiplicities. At the same time, the inherently quantum-mechanical nature of these calculations makes them promising candidates to exploit the qualitatively new computational capabilities of emerging quantum computing hardware. In this talk I will present recent advances in quantum computer algorithms for perturbative QFT calculations, including early hints that such machines could eventually outperform classical computers in this domain. Demonstrations are performed on state-of-the-art quantum computers with O(100) qubits. We anticipate that in time the work can lead to improved reach and precision for perturbative QFT predictions.

Speaker: Herschel Chawdhry (Florida State University)

2026_05_28_Loopfest_BNL_Advances_Quantum_Computation_perturbative_QFT_scattering_1548.pdf

43 $\mathcal{O}(\alpha \alpha_s^2)$ corrections to the top mass

We present the calculation of the 3-loop \mathcal{O}\alpha\alpha_s^2 corrections to the top quark mass. We discuss the evaluation of the elliptic integrals which appear as iterated solutions of a differential equation in canonical form.

Speaker: Mr Daniele Gaggero (SUNY Buffalo)

DG_Loopfest26.pdf

44 Off-shell triphoton production via quark loops from numerical integration

I will give an overview of our approach for the direct numerical integration of two-loop corrections to electroweak production. After locally subtracting infrared and ultraviolet singularities, we enable numerical integration in momentum space through analytic integration over the energy components of the loop momenta, subtraction of threshold singularities, and the use of importance sampling with the multi-channel Monte Carlo method. I will illustrate these features with examples from our recent calculations of fermionic two-loop corrections to di- and triboson production at the LHC and will show preliminary results towards the complete two-loop corrections.

Speaker: Dario Kermanschah

loop_fest_26_dario.pdf

18:00 Dinner at Desmond's, East Wind, Meet in Seminar Lounge for carpools

Friday 29 May

FRIDAY LUNCH INFO

Convener: Sally Dawson (BNL)

Friday.pdf

FCC-ee

Convener: Patrick Meade (SBU)

45 Higgs Physics for Future Colliders

Speaker: Matthew Forslund (Princeton)

LoopFest2026_MForslund_5-29-26.pdf

46 Event Generators for FCC-ee

Speaker: Juergen Reuter (DESY)

2026_05_LoopFest.pdf

47 Higher order corrections for FCC-ee

Speaker: Ayres Freitas (University of Pittsburgh)

LoopFest 2026.pdf

48 Efficient computation of soft and beam functions at NNLO

Speaker: Emmet Byrne

Emmet_LoopfestBNL_2026.pdf

10:45 Coffee

Closing Session

Convener: Robert Szafron (Brookhaven National Laboratory)

49 QED Corrections for e+e-

Speaker: Francesco Ucci (Pavia)

BNL_ucci.pdf

50 Global Fits of the Standard Model and Beyond

Speaker: Laura Reina (Florida State University)

loopfest26.pdf

51 Toward AI-based new physics searches at the EIC

Speaker: Felix Ringer (YITP Stony Brook)

Loopfest26_FRinger.pdf

52 SubTropica

Speaker: Sebastian Mizera (Columbia)

Mizera_LoopFest_XXIV.pdf

13:05 Conference Close