Transverse Energy-Energy Correlator for Vector Boson-Tagged Hadron Production in $pp$ and $pA$ collisions

TL;DR

This paper studies the transverse energy-energy correlator (TEEC) in vector boson-tagged hadron production in proton-proton and proton-nucleus collisions, incorporating nuclear effects and resummation techniques to probe nuclear modifications in TMD physics.

Contribution

It introduces the TEEC observable as a sensitive probe for nuclear modifications in TMD physics, including nuclear effects in the shape of the $ au$-distribution and rapidity dependence.

Findings

TEEC is sensitive to nuclear modifications in TMD physics.

Shape changes in $ au$-distribution reveal transverse momentum broadening.

Rapidity measurements explore nuclear effects in collinear TMD PDFs.

Abstract

We investigate the transverse energy-energy correlator (TEEC) event-shape observable for back-to-back $\gamma + h$ and $Z + h$ production in both $pp$ and $pA$ collisions. Our study incorporates nuclear modifications into the transverse-momentum dependent (TMD) factorization framework, with resummation up to next-to-leading logarithmic (NLL) accuracy, for TEEC as a function of the variable $\tau = \left(1 + \cos{\phi} \right)/2$, where $\phi$ is the azimuthal angle between the vector boson and the final hadron. We analyze the nuclear modification factor $R_{pA}$ in $p\mathrm{Au}$ collisions at RHIC and $p\mathrm{Pb}$ collisions at the LHC. Our results demonstrate that the TEEC observable is a sensitive probe for nuclear modifications in TMD physics. Specifically, the changes in the $\tau$-distribution shape provide insights into transverse momentum broadening effects in large nuclei, while measurements at different rapidities allow us to explore nuclear modifications in the collinear component of the TMD parton distribution functions in nuclei.