Speaker
Description
We study cold nuclear matter effects on Drell-Yan production at small and moderate $p_T$ in proton/pion-nucleus collisions using a new transverse-momentum 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 $x\rightarrow 1$ and collinear divergences at the endpoints $x=0,1$ of the emission spectra. We further show that the rapidity divergences lead to 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 $\pi A$ collisions and provides calculations with improved accuracy for hadron production in cold QCD processes at RHIC and LHC.
| Category | Theory |
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