The aT distribution of the Z boson at hadron colliders

TL;DR

This paper introduces and theoretically analyzes a new variable, $a_T$, for studying the low transverse momentum region of Z bosons at hadron colliders, using advanced resummation techniques.

Contribution

It provides the first theoretical resummation of the $a_T$ variable at next-to-leading logarithmic accuracy and compares it with the traditional $p_T$ distribution.

Findings

Resummed $a_T$ results agree with fixed-order calculations at two-loop level.

Identifies key physical differences between $a_T$ and $p_T$ distributions.

Demonstrates $a_T$ as a potentially more precise probe of low $p_T$ region.

Abstract

We provide the first theoretical study of a novel variable, $a_T$, proposed in Ref.[1] as a more accurate probe of the region of low transverse momentum $p_T$, for the $Z$ boson $p_T$ distribution at hadron colliders. The $a_T$ is the component of $p_T$ transverse to a suitably defined axis. Our study involves resummation of large logarithms in $a_T$ up to the next-to--leading logarithmic accuracy and we compare the results to those for the well-known $p_T$ distribution, identifying important physical differences between the two cases. We also test our resummed result at the two-loop level by comparing its expansion to order $\alpha_s^2$ with the corresponding fixed-order results and find agreement with our expectations.