A new quantity for studies of dijet azimuthal decorrelations

TL;DR

This paper introduces a new measurable quantity, $R_{ riangle ext{phi}}$, for analyzing dijet azimuthal decorrelations in hadron collisions, which can help determine the strong coupling constant and tune event generators.

Contribution

It proposes a novel ratio, $R_{ riangle ext{phi}}$, that reduces PDF uncertainties and enables precise $ ext{alpha}_s$ extraction from collider data.

Findings

NLO pQCD predictions for $R_{ riangle ext{phi}}$ at LHC and Tevatron.

Estimated theoretical uncertainties for $ ext{alpha}_s$ extraction.

Demonstrated potential for tuning Monte Carlo event generators.

Abstract

We introduce a new measurable quantity, $R_{\Delta \phi}$, for studies of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations in hadron-hadron collisions. In pQCD, $R_{\Delta \phi}$ is computed as a ratio of three-jet and dijet cross sections in which the parton distribution functions cancel to a large extent. At the leading order, $R_{\Delta \phi}$ is proportional to $\alpha_s$, and the transverse momentum dependence of can therefore be exploited to determine $\alpha_s$. We compute the NLO pQCD theory predictions and non-perturbative corrections for $R_{\Delta \phi}$ at the LHC and the Tevatron and investigate the corresponding uncertainties. From this, we estimate the theory uncertainties for $\alpha_s$ determinations based on $R_{\Delta \phi}$ at both colliders. The potential of $R_{\Delta \phi}$ measurements for tuning Monte Carlo event generators is also demonstrated.