QCD Evolution 2025

May 19, 2025, 8:00 AM → May 23, 2025, 5:00 PM US/Eastern

CEBAF Center, Auditoriium (Jefferson Lab)

Nobuo Sato (Jefferson Lab), Alexei Prokudin (JLab)

QCD Evolution 2025 will be held at Jefferson Lab, Newport News, VA, USA on May 19- May 23, 2025. 

The QCD Evolution workshop series started in 2011. Since this initial meeting, QCD Evolution has grown to be a leading hadron physics meeting with a focus on hadron tomography.

The main objective of the QCD Evolution Workshop is to provide a forum to discuss the recent scientific accomplishments in areas such as generalized parton distributions (GPDs), transverse momentum distributions (TMDs), and small-x physics, together with advances in perturbative and non-perturbative techniques within QCD, such as lattice QCD and effective field theory (EFT) techniques.

In doing so this workshop also aims to support and guide the physics programs at facilities such as Jefferson Lab, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab, Fermi National Accelerator Laboratory, and the Large Hadron Collider (LHC) complex at CERN. The workshop is also central to the building of the next-generation nuclear physics facility in the US, the Electron Ion Collider (EIC).

The Local Organizing Committee:

• Nobuo Sato (JLab, Chair)
• Joseph Karpie (JLab) 
• Wally Melnitchouk (JLab)
• David Richards (JLab)
• Marco Zaccheddu (JLab)
• Zhite Yu (JLab)

The International Advisory Committee: 

Alessandro Bacchetta (Pavia), Ian Balitsky (ODU and JLab), Daniel Boer (Groningen), Elena Boglione (Turin), Ian Cloet (ANL), Martha Constantinou (Temple), Umberto D'Alesio (Cagliari),  Leonard Gamberg (PSU Berks), Yoshitaka Hatta (BNL), Zhongbo Kang (UCLA), Yuri Kovchegov (OSU), Asmita Mukherjee (IIT Bombay), Barbara Pasquini (Pavia), Alexei Prokudin (PSU Berks and JLab), Jianwei Qiu (JLab), Anatoly Radyushkin (ODU and JLab), Ivan Vitev (LANL), Feng Yuan (LBNL).

Please, send your questions and inquiries about the event to qcd_evolution2025@jlab.org.

 

free day

suggestions.pdf

Mon, May 19

8:15 AM → 8:50 AM Check in

Check in at the front table by the security desk to receive your name tag for the conference.

Convener: Mrs Bernice Whitehead (Jefferson Lab)

8:50 AM → 9:00 AM Welcome

Speaker: David Dean (TJNAF)

9:00 AM → 10:30 AM Plenary

Convener: Jianwei Qiu (Jefferson Lab)

Prokudin_QCD_Evolution25.pdf

9:00 AM Physics at the Intensity Frontier with SoLID: Current Status and Prospects

Speaker: Zein-Eddine Meziani (Argonne National Laboratory)

QCDEVOLUTION2025-SoLID-Meziani-final.pdf

9:30 AM Proton GPDs from Lattice QCD at Leading Twist and Beyond

Speaker: Martha Constantinou (Temple University)

QCD_Evolutions_2025_Constantinou.pdf

10:00 AM Thoughts on Photons, from JLab to the EIC

Speaker: George Sterman (SBU)

sterman-evolution-25-05.19-final-final.pdf

10:30 AM → 11:00 AM Coffee

11:00 AM → 12:00 PM Plenary

Convener: David Richards (Jefferson Lab)

Prokudin_QCD_Evolution25.pdf

11:00 AM Latest Developments in the Theory of Multi-Hadron Fragmentation Functions

High-energy collision processes where multiple hadrons are detected in the final state provide a rich structure to probe QCD dynamics. Establishing the correct quantum field-theoretic operator definition of multi-hadron fragmentation functions is critical in this regard. I will discuss the latest developments in the theory of multi-hadron fragmentation functions in interpreting them as number densities and deriving their associated evolution equations as well as their connection to factorization formulas.

Speaker: Daniel Pitonyak (Lebanon Valley College)

Pitonyak_QCDEvo_2025.pdf

11:30 AM Resummation of Flattened Jet Angularity Using Soft-Collinear Effective Theory

Jet angularity is a classic substructure observable which probes the angular distribution of jet constituents. While soft-drop grooming may suppress complicated contributions from wide-angle, soft radiation, the dependence on jet algorithm also limits the theoretical precision to higher accuracy. In this work we provide resummed calculations of flattened jet angularity which generalizes the power-law angular weight to generic functions using soft-collinear effective theory. This observable provides a new and flexible way of probing jet substructure phase space with applications in boosted particle tagging and hard probes of nuclear matter.

Speaker: Yang-Ting Chien (GSU)

QCDEvo_Flat_2025_Chien.pdf

12:00 PM → 2:00 PM Lunch

2:00 PM → 3:30 PM Parallel I

Convener: Zhite Yu (Jefferson Lab)

2:00 PM Addressing the Deconvolution Problem in DVCS Through String-Based GPDs

Generalized parton distributions (GPDs) are accessible through experimental processes such as deep virtual Compton scattering (DVCS) and deep virtual meson production (DVMP). Extracting GPDs directly from Compton form factors is complicated by the inherent ambiguity of deconvolution when parametrizing GPDs directly in momentum fraction $x$-space using double distributions. To overcome this challenge, we propose parametrizing GPDs via conformal moments in $j$-space, which naturally satisfy the polynomiality condition mandated by Lorentz invariance and offer a clear physical interpretation in terms of spin-$j$ resonance exchanges in the $t$-channel. In this talk, which is based on PRL.133.241901 (2024) and PRD.110.114016 (2024), we introduce a novel string-inspired parametrization for nucleon quark and gluon GPDs, applicable across all skewness $\xi$. Our framework expresses conformal moments explicitly as combinations of skewness-independent nucleon spin-$j$ A-form factors and skewness-dependent nucleon spin-$j$ D-form factors. These structures emerge naturally from $t$-channel string exchanges within an anti-de Sitter (AdS) space, ensuring consistency with Lorentz invariance and unitarity. Leveraging empirical Mellin moments from existing parton distribution functions (PDFs), our approach establishes a unique mapping between conformal moments in $j$-space and GPDs in momentum fraction $x$-space at arbitrary skewness.

Speaker: Kiminad Mamo (William and Mary)

string-GPDs-QCD-Evolution-May-19-2025-Mamo.pdf

2:30 PM All-Order Factorization for Virtual Compton Scattering at next-to-leading Power

We discuss all-order factorization for the virtual Compton process at next-to-leading power (NLP) in the $\Lambda_{\rm QCD}/Q$ and $\sqrt{-t}/Q$ expansion (twist-3), both in the double-deeply-virtual case and the single-deeply-virtual case. We use the soft-collinear effective theory (SCET) as the main theoretical tool. We conclude that collinear factorization holds in the double-deeply virtual case, where both photons are far off-shell.
The agreement is found with the known results for the hard matching coefficients at leading order $\alpha_s^0$, and we can therefore connect the traditional approach with SCET. In the single-deeply-virtual case, commonly called deeply virtual Compton scattering (DVCS), the contribution of non-target collinear regions complicates the factorization. These include momentum modes collinear to the real photon and (ultra)soft interactions between the photon-collinear and target-collinear modes. However, such contributions appear only for the transversely polarized virtual photon at the NLP accuracy and in fact it is the only NLP $\sim (\Lambda_{\rm QCD}/Q)^1 \sim (\sqrt{-t}/Q)^1$ contribution in that case.
We therefore conclude that the DVCS amplitude for a longitudinally polarized virtual photon, where the leading power $\sim (\Lambda_{\rm QCD}/Q)^0 \sim (\sqrt{-t}/Q)^0$ contribution vanishes, is free of non-target collinear contributions and the collinear factorization in terms of twist-3 GPDs holds in that case as well.

Speaker: Jakob Schoenleber (Brookhaven National Laboratory)

All_order_factorization_of_DVCS_at_NLP__Talk_at_QCDevo_2025-1.pdf

3:00 PM Probing the Nucleon's Spin Structure: A String-Based Approach to Generalized Parton Distributions

We extend the formalism of Phys.Rev.Lett. 133 (2024) 24, 241901 to helicity generalized parton distributions (GPDs) with the skewness dependence modeled by t-channel exchanges of spin-j operators in AdS space. Based on the conformal moment expansion, the GPDs are obtained through Mellin-Barnes integrals which bypass the convolution problem and are valid for all values of the skewness parameter. With a minimal set of free parameters and the helicity parton distribution functions (PDFs) from the Asymmetry Analysis Collaboration (AAC) as an input, we predict the functional dependence of the conformal moments which enables us to construct the isoscalar, isovector, flavor separated and singlet quark and gluon helicity GPDs. Additionally, we compute the impact parameter representation of the associated helicity, angular momentum and spin-orbit contributions of the valence and sea constituents, enabling a full tomographic analysis of the proton spin decomposition.

Speaker: Florian Hechenberger (Stony Brook University)

HECHENBERGER_qcd_evo25.pdf

2:00 PM → 3:30 PM Parallel II

Convener: Adam Freese (Jefferson Lab)

2:00 PM Quark and Gluon GPD Global Analysis with DVCS and DVMP at NLO

We use the GUMP (Generalized Parton Distributions (GPDs) through Universal Moment Parametrization) framework, based on the conformal moments of GPDs, to perform a unified global analysis incorporating Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP) data. By performing simultaneous fits across these processes and incorporating Next-to-Leading Order (NLO) corrections, we are able to constrain the valence quark, sea quark and gluon GPDs.

Speaker: Fatma Aslan (JLab)

QCDEV25.pptx

2:30 PM An Impact Study of the 3D Structure of the Nucleon through DVCS and EIC Simulations

In this talk, I will present an impact study of pseudo-data from the future Electron-Ion Collider (EIC) on nucleon tomography and Compton Form Factors (CFFs), based on detector simulations performed with the EICROOT package. The pseudo-data are generated using the EpIC Monte Carlo event generator, a flexible and modular framework for simulating a broad range of exclusive processes, including DVCS, TCS, DDVCS, and various DVMP channels. A key feature of EpIC is the incorporation of second-order radiative corrections, which further enhances its precision for theoretical studies. Together, these tools provide a comprehensive toolset for probing the nucleon’s internal structure in preparation for future EIC experiments. I will also highlight recent CFF extractions from Jefferson Lab (JLab) data, which offer valuable insights but also reveal limitations in fully constraining these fundamental quantities. These challenges underscore the importance of the EIC’s expanded kinematic coverage and polarization capabilities in advancing CFF determinations and achieving a more complete understanding of the nucleon’s three-dimensional structure.

Speaker: Kemal Tezgin

QCD_Evolution_25.pdf

3:00 PM Probing the Proton's Correlated Spatial Structure Through Exclusive Processes

Generalized parton distributions (GPDs) serve as indispensable tools in filling in the gaps of the angular momentum sum rules as well as mapping the partonic spatial structure of hadrons. In this work, we extend the utility of GPDs in mapping the proton’s spatial structure beyond the typical one-body partonic picture, obtainable through Fourier transformations of GPDs to impact parameter space. Connecting two-body densities with the correlation functions that define double GPDs, we find that exclusive processes give access to relative distances and overlaps between partons.

Speaker: Panjsheeri Zaki

QCD_evolution_2025_ZP.pdf

3:30 PM → 4:00 PM Coffee

4:00 PM → 5:00 PM Parallel I

Convener: Joe Karpie

4:00 PM Zero Mode Issue in the Minus-Minus Component Calculation of the Meson-Photon Transition Form Factors in the Light-Front Dynamics

Zero mode issue in the minus-minus component calculation of the transition form factors in the light-front dynamics Among the three forms of Hamiltonian dynamics Dirac proposed in 1949, the light-front dynamics (LFD) has the most kinematical Poincare operators. In particular, the longitudinal boost operator becomes kinematical in the LFD. The LFD has very distinct vacuum properties, leading to its zero-mode issue which complicates calculations. The minus components in the LFD, related to higher-twist terms in the PDF and GPD formulations, have been notoriously difficult to calculate. In this talk, I will discuss the "minus-minus" component of the transition amplitude in the meson to two photon process, and discuss the role light-front zero-modes play. I will show the existence of spurious form factors, and that they cancel when the light-front time-ordered diagrams are summed. I will discuss the implication of this toy calculation for the GPD formulation.

Speaker: Bailing Ma (Argonne Natioinal Lab)

talkMay19.pdf

4:30 PM D-term and Dispersion Relations beyond Kinematic Twist-4

Quantum Chromodynamics (QCD) is the theoretical framework to study hadrons by means of their fundamental degrees of freedom, i.e.~quarks and gluons, collectively referred to as partons. QCD defines many types of distributions describing a given hadron in terms of partons. For the purposes of this talk, we are interested in the so-called generalized parton distributions (GPDs) which are off-forward matrix elements of quark and gluon operators and are typically accessed in exclusive Compton scattering. Convolutions of GPDs with coefficient functions describing the interaction of photons with the partons in the hadron are named Compton form factors (CFFs). Real and imaginary parts of CFFs are related by subtracted'' dispersion relations, i.e.~the difference between the real and imaginary parts is given by a constant. This subtraction constant can be written by means of the so-called $D$-term, which is one of the functions that parameterize the GPDs. The $D$-term is of special interest in hadron physics as it is the bridge connecting the subtraction constant (accessible in experiments by measurements of the CFFs) to the internal distribution of pressure in the hadron. The latter is given the gravitational form factor (GFF) $C$. These GFFs are functions which parameterize the QCD energy-momentum tensor and can be related tomechanical'' properties of the hadron such as mass, pressure or shear forces. In this talk, we propose a dispersion relation valid to all-orders in perturbation theory and up to kinematic twist four accuracy in order to study the $D$-term and its implications in the subtraction constant and the pressure inside the hadron.

Speaker: Victor Martinez-Fernandez

VMartinezFernandez_qcdEvol_slides__2025_.pdf

4:00 PM → 5:00 PM Parallel II

Convener: Marco Zaccheddu (Jefferson Lab)

4:00 PM Progress Towards the Extraction of GPDs Utilizing Machine Learning

I will present recent progress on the extraction of GPDs from data utilizing machine learning.

Speaker: Eric Moffat (Argonne National Lab)

Moffat_QCDEv_5-19-25.pdf

4:30 PM The Ecology of Uncertainty: Capturing Epistemic Doubt in Hadron Structure Analyses

Inverse problems are ubiquitous in hadron structure and tomography, where accurately characterizing uncertainties is crucial for unraveling new physics hiding within these uncertainties. In this new precision era of QCD, it is vital to create a translation between our physics and next generation AI/ML algorithms, using tools such as evidential deep learning and information-theoretic metrics to capture and separate contributions from aleatoric, epistemic, and distributional uncertainties. My research focuses on deploying evidence-based machine learning methods to decode parton distribution functions (PDFs) while exploring the vast parameter space of phenomenological and beyond-the-Standard-Model scenarios. Incorporating physics observables such as lattice QCD constraints and experimental measurements within these AI/ML paradigms refines the fidelity of PDF extractions and deepens our understanding of non-perturbative QCD. Ultimately, this integrated approach pushes the frontier of hadron structure discovery, aligning cutting-edge AI/ML progress with emerging opportunities at existing and future experimental physics facilities such as the EIC.

Speaker: Brandon Kriesten (Argonne National Lab)

Kriesten_QCDEvolution_2025.pdf

5:30 PM → 6:30 PM Reception

Come meet & great with some of the world's most renowned minds and enjoy a variety of light delectable hors d’oeuvres.

Tue, May 20

9:00 AM → 10:30 AM Plenary: Plenay

Convener: M Gabriel Santiago (Center for Nuclear Femtography)

Prokudin_QCD_Evolution25.pdf

9:00 AM Perturbative Corrections to Quark TMDPDFs in the Background-Field Method

I'll discuss calculation of the NLO corrections to the unpolarized quark TMDPDFs using the factorization scheme defined in arXiv:2311.16402. The scheme aims to take into account the all collinear twist content of the TMDPDFs in the region of large $b_\perp\lesssim\Lambda^{-1}_{QCD}$ and bridge together the limits of large and small-x. I'll discuss different aspects of this derivation including the role of the QCD equations of motion.

Speaker: Andrey Tarasov (North Carolina State University)

Tarasov_Evolution.pdf

9:30 AM Probing Small-x Helicity and OAM Distributions in Particle Production at RHIC and EIC

Speaker: Yuri Kovchegov (The Ohio State University)

Evolution_2025.pdf

Evolution_2025.pptx

10:00 AM Unveiling off lightcone effects in hadronic processes

The spacetime structure underlying hadronic processes plays a
central role in shaping their factorization properties. In many
important cases, the relevant dynamics unfold along two opposing
light-cone directions, and any deviation from the lightcone is commonly
assumed to be negligible at leading power. In this presentation, I will
demonstrate the significance of these off lightcone effects and reveal
the universal geometric features they share across seemingly unrelated
processes. Special emphasis will be given to the role of the
Collins–Soper kernel, and specifically its unexpected appearance in the
threshold limit of Deep Inelastic Scattering (DIS).

Speaker: Andrea Simonelli (ODU and JLAB)

QCDevolution_2025.pdf

10:30 AM → 11:00 AM Coffee

11:00 AM → 12:30 PM Plenary

Convener: Alexei Prokudin (JLab)

Prokudin_QCD_Evolution25.pdf

11:00 AM Status of the Simultaneous Global Analysis of PDFs and TMDs

Speaker: Patrick Barry (Argonne National Lab)

Barry_QCD25.pdf

11:30 AM First Neural-Network Extraction of Unpolarized Transverse-Momentum-Dependent Distributions

We present the first extraction of transverse-momentum-dependent distributions of unpolarized quarks from experimental Drell-Yan data using neural networks to parametrize their nonperturbative part. We show that neural networks outperform traditional parametrizations providing a more accurate description of data. This work establishes the feasibility of using neural networks to explore the multi-dimensional partonic structure of hadrons and paves the way for more accurate determinations based on machine-learning techniques.

Speaker: Chiara Bissolotti (Argonne National Laboratory)

2025_QCDEvolution_v3.pdf

12:00 PM Experimental Program at JLab to Explore Tensor-TMDs in Deuteron

Speaker: Nathaly Santiesteban (University of New Hampshire)

Santiesteban_2025_QCDevoluion.pdf

12:30 PM → 2:00 PM Lunch

2:00 PM → 3:00 PM Parallel I

Convener: Yuxun Guo (Lawrence Berkeley National Lab)

2:00 PM Imaging Bound Nucleons

In this talk, I will discuss recent advances in our ability to image parton distribution functions (PDFs) in bound nucleons. I will review topics from last year’s QCD Evolution workshop, such as methods for extracting nuclear-modified PDFs and TMDs. Additionally, I will discuss perturbative approaches that show how the evolution of TMD PDFs in Drell-Yan (p+A) collisions follows a BFKL evolution equation, arising from interactions between the collinear mode and the anti-collinear medium. I will also explore how these methods can be used to study TMD fragmentation functions (FFs) in semi-inclusive deep-inelastic scattering (SIDIS) with nuclei. Finally, I will discuss how these techniques can be generalized to other PDFs and how they can aid in imaging the properties of a Quark-Gluon Plasma.

Speaker: John Terry (Los Alamos National Lab)

QCD-Evolution-2025-2.pdf

2:30 PM Probing Hadron Structure and Hadronization at Colliders Using Chiral Effective Theory

Speaker: Marston Copeland (Duke University)

2:00 PM → 3:00 PM Parallel II

Convener: Fatma Aslan (JLab)

2:00 PM Upgrading the Knowledge on TMD Distributions in the Proton

The understanding of the three-dimensional internal structure of the proton has significantly been developed over the past few decades. In particular, the extraction of Transverse Momentum Dependent distributions (TMDs) from global fits of experimental data has now reached an impressive level of precision. In this talk, I will present first indications of flavor dependence emerging from the latest simultaneous extraction of unpolarized quark TMD parton distribution functions (PDFs) and fragmentation functions (FFs), based on a global analysis of Drell–Yan and Semi-Inclusive DIS data at next-to-next-to-next-to-leading logarithmic (N3LL) accuracy within the MAP collaboration framework.
I will also discuss the extension of our knowledge of the proton's 3Ds tructure in the case of longitudinal polarization. In particular, I will show recent results on the extraction of the quark helicity TMD PDF, which provide insight into the differences in the three-dimensional motion of quarks with spin parallel or antiparallel to the longitudinal
polarization of the proton.

Speaker: Matteo Cerutti (Hampton University and Jefferson Lab)

QCDEvo25_key.pdf

2:30 PM Towards a Pixel-Based Imaging of TMDs Distribution Functions

Speaker: Marco Zaccheddu (Jefferson Lab)

MZ_qcdevo_2025.pdf

3:00 PM → 3:30 PM coffee

3:30 PM → 4:35 PM Parallel I

Convener: Chiara Bissolotti (Argonne National Laboratory)

3:30 PM EEC and the extraction of Collins-Soper kernel

In this work we explore the possibilities to obtain the values of the CollinsSoper kernel and the strong coupling constant offered by what so far is the highest order result ever achieved in perturbation theory, that is for the energy correlators in the back-to-back limit at $N^4LL+N^3LO$.
The cross-section was implemented within ARTEMIDE’s code, using the $\zeta$-prescription for the runnings needed to sum up the large logarithms.
In contrast to the perturbative computation, the experimental data avaliable is from several years ago, but we tried to consider, to the best of our knowledge, the largest set of points in the analysis, for which we had to deal with some issues that will be briefly discussed also in this talk.
Finally we will give our predictions for the measurement of this observable in Belle and FCC-ee.

Speaker: Alejandro Bris (Universidad Complutense Madrid)

QCD_Evolution_2025.pdf

4:00 PM Kinematic Power Corrections in TMD Factorization

I will present the study of the DY and SIDIS structure functions within the TMD factorization theorem with the inclusion of Kinematic Power Corrections (KPCs). This new theory allows the description of previously theoretically inaccessible parts of the cross-section in a Lorentz invariant manner using only twist-two TMD distributions. Examples of application include Drell-Yan angular distributions and the Lam-Tumg relation, and the subleading SIDIS structure functions FUU,T and FUU,L. The impact of these corrections to the present and future SIDIS measurements is discussed.

Speaker: Sara Piloneta

Piloñeta_QCDEvolution2025.pdf

3:30 PM → 5:00 PM Parallel II

Convener: Eric Moffat (Argonne National Lab)

3:30 PM On the partonic structure of hadrons from low to high transverse-momentum

Speaker: Leonard Gamberg (Penn State Berks)

QCD_Evo_2025_Gamberg-2.pdf

4:00 PM New Insights into Lambda Fragmentation Functions

In this talk I present a new determination of the unpolarised fragmentation functions (FFs) for Lambda production from single-inclusive e+e- annihilation, semi-inclusive deep-inelastic scattering and pp collisions data. The analysis is done at both next-to-leading order (NLO) and next-to-next-to-leading order (NNLO). We extract the unpolarised FFs defining a parametrisation in terms of a neural network and determine their uncertainties with a Monte Carlo sampling method.

Speaker: Alessia Bongallino (Universidad del País Vasco UPV/EHU)

ABongallino_QCDEv2025.pdf

4:30 PM Energy Independence of the Collins Asymmetry in pp Collisions at STAR

Study of the origin of transverse single-spin asymmetries has triggered the development of the twist-3 formalism and the transverse-momentum-dependent parton distribution functions (TMDs). Measurement of the azimuthal distribution of identified hadrons within a jet in transversely polarized hadronic interactions provides an opportunity to study the TMD physics in the final state, {\it i.e.}, the Collins effect, which involves the convolution of the quark transversity with the Collins fragmentation functions. Significant discrepancies have been observed between experimental measurements of the Collins effect and theoretical predictions. Further precise measurements of the Collins effect can provide new insights into the three-dimensional structure of the proton. STAR experiment at RHIC has reported precision measurements of Collins asymmetries from jet + $\pi^{\pm}$ production in transversely polarized ${pp}$ collisions at a center-of-mass energy of $\sqrt{s}$ = 200 GeV. The STAR experiment reports high precision measurements of the Collins asymmetries for $\pi^{\pm}$ within jets from transversely polarized ${pp}$ collisions at $\sqrt{s}$ = 510 GeV. With energy-scaled jet $x_T$= $2p_T/\sqrt s$, a remarkable consistency is observed for Collins asymmetries of $\pi^{\pm}$ between 200 GeV and 510 GeV. This indicates that the Collins asymmetries are nearly energy independent, with at most a very weak scale dependence, in $pp$ collisions. This energy independence is significantly contrast to predictions that TMD evolution of the Sivers function leads to a substantial suppression of TSSA for $W^{\pm}$ production. These results extend to high momentum scales ($Q^2$ up to 3400 GeV$^2$) and enable unique tests of evolution and universality in the transverse-momentum-dependent formalism, thus providing important constraints for the Collins fragmentation functions.

Speaker: Yixin Zhang (Shandong University)

Yixin_QCD_evolution_2025.pdf

Wed, May 21

9:00 AM → 10:30 AM Plenary

Convener: Yoshitaka Hatta (Brookhaven National Laboratory)

Prokudin_QCD_Evolution25.pdf

9:00 AM Connecting Theory to Experiment and Event Generator Development for Hard Exclusive Reactions

I would like to present recent work done for developing an event generator aimed at making projections for hard exclusive reactions such as Compton-like reactions and meson production, for JLab to EIC energies. We extended our framework to include new reactions (phi, gamma-meson...), radiative corrections, etc. In this talk we also would like to discuss the connections between this work and the use of AI/ML tools to duplicate these simulations for systematic studies of error propagation in Compton Form Factor fits. Finally, we will show projections for observables measurable in near-coming JLab experiments, and our impact studies on how CFF fits will be improved provided these new measurements in a multichannel approach.

Speaker: Marie Boer (Virginia Tech)

9:30 AM Quantum Anomaly and GPDs

Speaker: Shohini Bhattacharya (University of Connecticut)

QCDevolution25_SB.pdf

10:00 AM Proton Gravitational Form Factors with Threshold Heavy-Quarkonium Production at NLO

I will discuss some recent progresses in constraining the gravitational form factors (GFFs) of the proton via near-threshold heavy quarkonium production with next-to-leading order alpha_S corrections. Particularly, I will show with Bayesian inference that such processes provide important constraint on the gluonic GFFs as well as the quark GFFs whose contributions emerge at next-to-leading order.

Speaker: Yuxun Guo (Lawrence Berkeley National Lab)

10:30 AM → 11:00 AM Coffee

11:00 AM → 12:30 PM Plenary

Convener: Martha Constantinou (Temple University)

Prokudin_QCD_Evolution25.pdf

11:00 AM Reframing Azimuthal Modulations in Hard Exclusive Diffraction Processes

I am going to present a new formulation of the azimuthal modulations in hard exclusive diffraction processes. These are crucial in the phenomenological extraction and separation of various generalized parton distributions (GPDs). Traditionally, GPDs could be extracted from angular modulations of the deeply virtual Compton scattering (DVCS) in the Breit frame. However, the Bethe-Heitler subprocess (BH) interferes with the DVCS and contaminates the azimuthal modulations from DVCS, making it challenging to extract GPDs cleanly. We provide a new formalism and choice of frame to describe the azimuthal distributions, and demonstrate that they are more suitable for experimental analysis to separate contributions to a physical cross section from GPD sensitive (such as DVCS) and insensitive (e.g., BH) subprocesses in a consistent and uniform way.

Speaker: Zhite Yu (Jefferson Lab)

QCDEVO_DVCS_ZhiteYu.pdf

11:30 AM All About Pion from Lattice QCD: From Form Factors to TMDPDFs

Speaker: Swagato Mukherjee (Brookhaven National Laboratory)

Mukherjee.pdf

12:00 PM Perturbative Results of the Axial Current and the Axial Anomaly

In the Standard Model of particle physics, the axial current is not conserved, due both to fermion masses and to the axial anomaly. Using perturbative quantum chromodynamics, we calculate matrix elements of the local and non-local axial current for a gluon target, clarifying their connection with the axial anomaly. In so doing, we also reconsider classic results obtained in the context of the nucleon spin sum rule as well as recent results for off-forward kinematics. An important role is played by the infrared regulator, for which we put a special emphasis on the nonzero quark mass. We highlight cancellations that take place between contributions from the axial anomaly and the quark mass, and we elaborate on the relation of those cancellations with the conservation of angular momentum. Furthermore, we discuss the connection of related recent publications and our work.

Speaker: Ignacio Castelli (Physics Department, Temple University, Philadelphia)

slides

12:30 PM → 2:00 PM Lunch

2:00 PM → 5:00 PM Free afternoon

5:30 PM → 8:00 PM Dinner

Enjoy a wonderful evening with collogues to include dinner and conversations.

Thu, May 22

9:00 AM → 10:30 AM Plenary

Convener: Robert Edwards (Jefferson Lab)

Prokudin_QCD_Evolution25.pdf

9:00 AM Learning Parton Structure from Lattice QCD

Speaker: Joe Karpie

Karpie_qcd_evo_2025.pdf

9:30 AM tiktaalik: Code for Ultra-Fast GPD Evolution

Generalized parton distributions (GPDs) are functions of four variables, one of which is a renormalization scale. The functional dependence on this renormalization scale is fully determined by a renormalization group equation---or "evolution equation"---that can be derived from perturbative QCD. A fast numerical implementation of the scale evolution is vital to any global phenomenology effort. Moreover, for a framework leveraging neural networks, differentiability is also necessary. In this talk, I will discuss an ultra-fast, differentiable implementation of GPD evolution in momentum fraction space, in which the evolution equation itself is (approximately) rendered as a differential matrix equation.

Speaker: Adam Freese (Jefferson Lab)

Freese_2025.05.22_qcd_evolution.pdf

10:00 AM Investigating the Transverse Structure of Hadrons Using Parton Pseudodistributions

Within the pseudo-PDF framework, we investigate the perturbative contributions to correlators that are used to study transverse momentum dependent parton distributions (TMDs) on the lattice. Our results contain the full perturbative corrections which arise as artifacts from performing the calculation for a Euclidean separation between the parton fields, as well as the corrections which yield the evolution equations for the TMDs.  This gives a path to extraction of the genuine non-perturbative features of the three-dimensional structure of the hadrons from lattice calculations.

Speaker: Gabriel Santiago (Center for Nuclear Femtography)

santiago_evolution_2025.pdf

10:30 AM → 11:00 AM Coffee

11:00 AM → 12:30 PM Plenary

Convener: Shohini Bhattacharya (University of Connecticut)

Prokudin_QCD_Evolution25.pdf

11:00 AM Recent Results and Future Prospects of Di-Hadron Production in Polarized Proton-Proton Collisions at RHIC

Speaker: Bernd Surrow (Temple University)

11:30 AM Global QCD Analysis of Proton’s Transverse Spin Structure through TMDs and DiFFs

A new global QCD analysis by the JAM collaboration performs the first extraction of transversity PDFs and tensor charges using both the Transverse Momentum Distribution (TMD) and Dihadron Fragmentation Function (DiFF) channels simultaneously, including all currently available experimental data. Known theoretical constraints on transversity, namely, its small-$x$ asymptotic behavior and the Soffer bound, are incorporated in the fit. We test compatibility with lattice-QCD calculations for the tensor charges by including them in the fit, in order to further examine whether there is a universal nature to all of the available information on transversity distributions and tensor charges of the nucleon.

Speaker: Christopher Cocuzza (College of William & Mary)

QCDEvolution2025.pdf

12:00 PM SIDIS Studies with CLAS12

Speaker: Harut Avagyan (Jefferson Lab)

2025-QCD-May22.pdf

2025-QCD-May22.pptx

12:30 PM → 2:00 PM Lunch

2:00 PM → 3:30 PM Parallel I

Convener: Swagato Mukherjee (Brookhaven National Laboratory)

2:00 PM Better operators for boosted hadrons

Pion and nucleon operators with spin structures inspired by light-cone physics and perturbative QCD have recently been discovered to have kinematically enhanced ground-state overlap and signal-to-noise in lattice QCD calculations with large momentum. I will discuss the physics of these operators and exploratory lattice QCD results for parton structure functions using these new operators.

Speaker: Michael Wagman (FNL)

Wagman_QCD_Evolution_25.pdf

2:30 PM Disconnected Contributions in Pseudo-PDF Reconstruction

I will present on the extraction of disconnected contribution to the isoscalar matrix elements for light and strange quarks for the proton using Lattice QCD. While the connected contributions dominate the disconnected contributions are non-zero and must be considered to properly determine the matrix elements. In the case of the strange quark, there is no connected contribution, thus it is paramount to correctly measure these contributions.

Speaker: Christopher Chamness (The College of William & Mary)

QCD_Evolution_2025.pdf

2:00 PM → 3:30 PM Parallel II

Convener: Jia-Yue Zhang (Jefferson Lab)

2:00 PM Entanglement as a Probe of Hadronization

Speaker: Charles Joseph Naїm (Stony Brook University (CFNS))

QCD_evolution_2025_NAIM.pdf

2:30 PM Quark TMDs from back-to-back Dijet pPduction at Forward Rapidities in pA Collisions beyond Eikonal Accuracy in the CGC

We study dijet production in pA collisions at forward rapidities at next-to-eikonal accuracy. We restrict ourselves to the next-to-eikonal corrections that are induced by the quark background field of the target. Computing the scattering amplitudes, for all possible channels, in the back-to-back limit allows the study of leading twist quark TMDs in the high energy limit. We indeed express the back-to-back production cross section in a factorized form with a quark TMD times associated hard factor for each channel. These TMDs show different gauge links (with future and past pointing stapple and more complex structures).

Speaker: Etienne Bianco

QCD_Evolution_2025-Etienne_Blanco.pdf

3:00 PM Probing Hadronization and Quark-Gluon Plasma Using Collinear-Drop Jet Observables

Speaker: Oleh Fedkevych (Georgia State University)

OFedkevych_22_05_25.pdf

3:30 PM → 4:00 PM Coffee

4:00 PM → 5:00 PM Parallel I

Convener: Michael Wagman (FNL)

4:00 PM Accessing the Nucleon Gluon Momentum Fraction using the Gradient Flow on the Lattice

Speaker: Alexandru Sturzu

Presentation.pdf

4:30 PM Parton Distributions from Boosted Fields in the Coulomb Gauge

Speaker: Xiang Gao (BNL&Tsinghua University)

QCDevo_XG.pdf

4:00 PM → 5:00 PM Parallel II

Convener: Patrick Barry (Argonne National Lab)

4:00 PM Proton Spin from Small-x With Constraints from the Valence Quark Model

We apply the valence quark model to constrain the non-perturbative initial condition for the small-x helicity evolution. The remaining free parameters are constrained by performing a global analysis to the available polarized small-x deep inelastic scattering data. A good description of the world data is obtained with only 8 free parameters. The model parameters are tightly constrained by the data, allowing us to predict the proton polarized structure-function to be negative at small x. Furthermore, we obtain the small-x quark and gluon spins, depending on the applied running coupling prescription.

Speaker: Daniel Adamiak (Ohio State University)

QCD Evolution - Valence Quark Model.pdf

4:30 PM Effects of Threshold Resummation for Large-x PDF in Large Momentum Effective Theory

Parton distribution functions (PDFs) at large $x$ are challenging to extract from experimental data, yet they are essential for understanding hadron structure and searching for new physics beyond the Standard Model. Within the framework of the large momentum $P^z$ expansion of lattice quasi-PDFs, we investigate large $x$ PDFs, where the matching coefficient is factorized into the hard kernel, related to the active quark momentum $x P^z$, and the threshold soft function, associated with the spectator momentum $(1-x) P^z$. The renormalization group equation of the soft function enables the resummation of the threshold double logarithms $\alpha^{k} \ln^{2k}(1-x)$, which is crucial for a reliable and controllable calculation of large $x$ PDFs. Our analysis with pion valence PDFs indicates that perturbative matching breaks down when the spectator momentum $(1-x)P^z$ approaches $\Lambda_{\rm QCD}$, but remains valid when both $x P^z$ and $(1-x)P^z$ are much larger than $\Lambda_{\rm QCD}$. Additionally, we incorporate leading renormalon resummation within the threshold framework, demonstrating good perturbative convergence in the region where both spectator and active quark momenta are perturbative scales.

Speaker: Yushan Su (UMD)

LaMET_asymptotic_analysis_V5.pdf

Fri, May 23

9:00 AM → 10:30 AM Plenary

Convener: Marie BOER (Virginia Tech)

Prokudin_QCD_Evolution25.pdf

9:00 AM New Avenues in Hadronic Physics at JLab with 22 GeV

Speaker: Patrizia Rossi (Jefferson Lab)

Rossi_QCD Evolution.pdf

9:30 AM Quasifragmentation Functions and Quasiparton Distributions in the Massive Schwinger Model

Speaker: Sebastian Grieninger (Stony Brook University)

Grieninger_QCD_evo_25.pdf

10:00 AM Kinematic Power Corrections to DVCS to Twist-Six Accuracy

We calculate $(\sqrt{-t}/Q)^k $ and $(m/Q)^k$ power corrections with $k\le 4$, where $m$ is the target mass and $t$ is the momentum transfer, to several key observables in Deeply Virtual Compton Scattering (DVCS). We find that the power expansion is well convergent up to $|t|/Q^2\lesssim 1/4$ for most of the observables, but is naturally organized in terms of $1/(Q^2+t)$ rather than the nominal hard scale $1/Q^2$. We also argue that target mass corrections remain under control and do not break QCD factorization for coherent DVCS on nuclei. These results remove an important source of uncertainties due to the frame dependence and violation of electromagnetic Ward identities in the QCD predictions for the DVCS amplitudes in the leading-twist approximation.

Speaker: Vladimir Braun (University of Regensburg)

QCD-Evolution-2025.pdf

10:30 AM → 11:00 AM Coffee

11:00 AM → 12:00 PM Plenary

Convener: Anatoly Radyushkin (ODU/JLab)

Prokudin_QCD_Evolution25.pdf

11:00 AM Rapidity Factorization and Rapidity Evolution in QCD

Speaker: Ian Balitsky (JLab/ODU)

QCDevol25.pdf

11:30 AM Gravitational Form Factors of Pions and Nucleons from Heavy Vector Meson Production Near Threshold

Speaker: Yoshitaka Hatta (Brookhaven National Laboratory)

QCD evolution.pdf

12:00 PM → 2:00 PM Lunch

2:00 PM → 3:30 PM Parallel I: Parallel

Convener: Eric Moffat (Argonne National Lab)

2:00 PM Partonic and Nuclear Dynamics Through the CJ Global Analysis Lens

Speaker: Alberto Accardi (Christopher Newport U. and Jefferson Lab)

CJ talk - Accardi.pdf

2:30 PM Impact of Parity-Violating DIS on the Nucleon Strangeness and Weak-Mixing Angle

Speaker: Richard Whitehill (Old Dominion University / Jefferson Lab)

QCD-Evolution-2025_RWhitehill.pdf

3:00 PM Markov chain Monte Carlo (MCMC) based Likelihood Analysis of spin structure function g1p from polarized DIS experiments

From polarized Deep Inelastic scattering (DIS) asymmetries, and cross-section data, it is possible to extract the polarized structure functions g1 and g2. In the Parton model picture of proton, the structure function g1p is expressed in terms of g1p = ∆Σ + ∆G, the net quark and gluon helicity contributions to the proton spin. This spin structure function can also be used to understand the controversies associated with the sign problem of ∆G. We present a rigorous approach to study the correlations between the spin structure function g1 with ∆Σ and ∆G. We perform a likelihood analysis of the polarized DIS spin structure function data using Markov chain Monte Carlo (MCMC) sampling method. The analysis shows preliminary results with a detailed explanation of the method employed. We also try to address some of the problems arriving in the approach which obstruct in studying the sign problem of ∆G.

Speaker: Saraswati Pandey (Banaras Hindu University)

QCD_Evolution25.pdf

2:00 PM → 3:30 PM Parallel II

Convener: Daniel Adamiak (Ohio State University)

2:00 PM Meson electroproduction at very high transverse momentum

When electrons strike a proton or nuclear target, there is a regime where electroproduction of the highest momentum pion or rho mesons proceeds by a perturbatively calculable process. The process is not the leading twist fragmentation process but rather a higher twist process that produces kinematically isolated mesons. Our calculations demonstrate, that in conditions that can be expected at JLab, there is a significant and broad kinematic region for the perturbative QCD mechanism of meson production. The application of this semiexclusive data would be to teach us more about parton distribution functions of the target at high Bjorken x and about the meson distribution amplitudes. In addition, there is a connection to generalized parton distribution calculations of exclusive processes in that the perturbative kernel is the same.

Speaker: Carl Carlson (William & Mary)

Carlson_QCDEvo_25.pdf

2:30 PM Two-Photon-Exchange Effects for the Azimuthal Asymmetries of SIDIS Cross Section

Calculations of the QED corrections to semi-inclusive deep-inelastic scattering (SIDIS) are crucial for studies of the 3D structure of the nucleon at JLab and future Electron Ion Collider (EIC). Previously, the important role of two-photon exchange (TPE) was discovered for the studies of nucleon structure in elastic electron-proton scattering. Here, we address the role of TPE corrections on the azimuthal asymmetries of SIDIS. Using the formalism developed in Ref. [2], we evaluate TPE corrections in a soft-photon approximation and demonstrate that the TPE mechanism alone can generate azimuthal asymmetries at a few per cent level that is crucial for interpretation of experimental data on azimuthal moments. In addition, TPE is shown to contribute to the prospective measurements of L/T separation in SIDIS [3]. The predictions are directly related to the anticipated asymmetries of electron/positron scattering cross sections that can be measured with future positron beams at JLab. References [1]. A. Afanasev, P.G. Blunden, D. Hasell, B.A.Raue, Prog. Part. Nucl. Phys. 95, 245 (2017). [2]. A. Afanasev, A. Aleksejevs, S. Barkanova, Phys. Rev. D 88, 053008 (2013). [3]. H. Avakian et al., Jefferson Lab Experiment E12-16-010C. [4]. A. Accardi, A. Afanasev, I. Albayrak, S. Ali, M. Amaryan, J. Annand, J. Arrington, A.Asaturyan, H. Atac, H. Avakian, et al., The European Physical Journal A 57, 261 (2021).

Speaker: Andrei Afanasev (GWU)

Afanasev_QCDEvolution2025.pdf

3:00 PM Quantum Algorithms for High Energy Evolution

Speaker: Shaswat Tiwari (North Carolina State University)

Quantum_evolution_Shaswat_S_Tiwari.pdf

3:30 PM → 4:00 PM Coffee

4:00 PM → 4:30 PM Plenary: closing

Convener: Alexei Prokudin (JLab)

Prokudin_QCD_Evolution25.pdf