Transverse-momentum-dependent (TMD) factorization in reactions with nuclei: From Drell-Yan to hadron production

Theoretical Division, Los Alamos National Laboratory, Los Alamos NM 87545, United States

^* e-mail: weiyaoke@ccnu.edu.cn
^** e-mail: ivitev@lanl.gov

Published online: 26 June 2024

Abstract

We study cold nuclear matter effects on Drell-Yan production at small and moderate p_T in proton/pion-nucleus collisions using a new transversemomentum dependent (TMD) factorization framework. Both collisional broadening and medium-induced radiative corrections in the initial state are considered in the soft-collinear effective theory with Glauber gluons (SCET_G) approach. We demonstrate that in-medium bremsstrahlung exhibits rapidity divergences as x → 1 and collinear divergences at the endpoints x = 0, 1 of the medium-induced emission spectra. We further show that the rapidity divergences lead to the Balitsky-Fadin-Kuraev-Lipatov (BFKL) evolution of the collision kernel and can be resummed into the transverse momentum broadening of particle production. In turn, the endpoints divergences of in-medium radiation can be resummed through the collinear evolution of parton densities in nuclear matter. The TMD factorization framework is applied to understand the transverse-momentum spectra of Drell-Yan pair production in pA and πA collisions and provides calculations with improved accuracy for hadron production in cold QCD processes at RHIC and LHC.