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...
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...
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...
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...
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.
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...
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....
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...
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...
I revisit the factorization of inclusive deep inelastic scattering near the kinematic threshold to explicitly track off-lightcone effects. Particle production develops around two opposite near-lightcone directions like in transverse-momentum-dependent processes, and the Collins-Soper kernel emerges as a universal function in the rapidity evolution of the relevant parton correlators. I clarify...
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...
