Nuclear Physics Seminars at BNL
Joint QED and QCD Factorization Approach to Lepton-Hadron Scattering
by
→
US/Eastern
Description
The factorization theorem plays an important role in the analysis of high energy QCD processes, separating the nonperturbative hadronic interaction into the universal parton distribution functions (PDFs) and fragmentation functions (FFs) and the process-dependent interactions into short distance perturbative calculations. However, the collision induced QED radiation can change the momentum of the exchanged but unobserved virtual photon, making the photon-hadron frame, where the factorization formalism for deeply inelastic scattering (DIS) and semi-inclusive DIS (SIDIS) was derived, ill defined. A new joint factorization approach treats QED and QCD radiation on equal footing, separating the leading power process-independent QED radiative contributions by introducing lepton distribution functions (LDFs) and lepton fragmentation functions (LFFs), while process-dependent effects are perturbatively calculated. These LDFs and LFFs are also universal, so data from experiments can be used to fit and describe these functions across a wide range of lepton scattering, and taking advantage of agentic AI to extract their non-perturbative nature is part of our recent Genesis proposal. In this talk, I apply this new hybrid factorization approach to lepton-hadron DIS and SIDIS. For DIS, I derive the NLO short distance perturbative contribution to the cross section and demonstrate the effects the QED radiation has on the cross section using this approach. I then show the effects on the SIDIS cross section using fixed order calculations for the unpolarized structure function (with a matching between the descriptions for low and high transverse momentum), first focusing on the effect of the radiative corrections on the main kinematic variables, especially the correlation between the internal transverse momentum and the external angular dependence. This new joint QED and QCD factorization method will be important for making predictions for the EIC.