Next-to-leading order transverse momentum broadening for Drell-Yan production in p+A collisions

TL;DR

This paper calculates the transverse momentum broadening for Drell-Yan production in proton-nucleus collisions at next-to-leading order, demonstrating the factorization and evolution of twist-4 nuclear correlations within perturbative QCD.

Contribution

It introduces a NLO calculation of transverse momentum broadening with a verified QCD evolution equation for twist-4 nuclear correlations, confirming their universality.

Findings

Verified factorization of NLO cross section into PDFs, twist-4 correlations, and hard coefficients.

Derived and confirmed the universality of the QCD evolution equation for nuclear gluon-quark correlations.

Demonstrated the predictive power of pQCD for parton multiple scattering in nuclear media.

Abstract

We present the nuclear transverse momentum broadening for Drell-Yan lepton pair production in p+A collisions at next-to-leading order (NLO) in powers of strong coupling constant $\alpha_s$. We verify that the transverse momentum weighted differential cross section in NLO perturbative QCD (pQCD) at twist-4 can be factorized into the convolution of parton distribution function of an active parton in the projectile proton, a twist-4 multiparton correlation function of the target nucleus, and perturbatively calculable hard coefficient function. We identify a QCD evolution equation for such a twist-4 nuclear gluon-quark correlation function, and verify its universality -- its process independence. This finding demonstrates the prediction power of pQCD factorization approach for studying parton multiple scattering in nuclear medium.