Determination of the strong coupling constant from transverse energy$-$energy correlations in multijet events at $\sqrt{s} = 13$ TeV with the ATLAS detector

TL;DR

This paper measures transverse energy correlations in multijet events at 13 TeV with ATLAS, compares results to advanced QCD calculations, and extracts a precise value of the strong coupling constant, testing QCD predictions at high energies.

Contribution

It provides the first comparison of transverse energy correlations with NNLO QCD calculations and extracts a precise value of alpha_s from LHC data.

Findings

Good agreement between data and NNLO QCD predictions.

Precise determination of alpha_s(m_Z) around 0.118 with small experimental uncertainty.

Validation of QCD scaling and renormalization group evolution at high energies.

Abstract

Measurements of transverse energy$-$energy correlations and their associated azimuthal asymmetries in multijet events are presented. The analysis is performed using a data sample corresponding to 139 $\mbox{fb\(^{-1}\)}$ of proton$-$proton collisions at a centre-of-mass energy of $\sqrt{s} = 13$ TeV, collected with the ATLAS detector at the Large Hadron Collider. The measurements are presented in bins of the scalar sum of the transverse momenta of the two leading jets and unfolded to particle level. They are then compared to next-to-next-to-leading-order perturbative QCD calculations for the first time, which feature a significant reduction in the theoretical uncertainties estimated using variations of the renormalisation and factorisation scales. The agreement between data and theory is good, thus providing a precision test of QCD at large momentum transfers $Q$. The strong coupling constant $\alpha_s$ is extracted differentially as a function of $Q$, showing a good agreement with the renormalisation group equation and with previous analyses. A simultaneous fit to all transverse energy$-$energy correlation distributions across different kinematic regions yields a value of $\alpha_\mathrm{s}(m_Z) = 0.1175 \pm 0.0006 \mbox{ (exp.)} ^{+0.0034}_{-0.0017} \mbox{ (theo.)}$, while the global fit to the asymmetry distributions yields $\alpha_{\mathrm{s}}(m_Z) = 0.1185 \pm 0.0009 \mbox{ (exp.)} ^{+0.0025}_{-0.0012} \mbox{ (theo.)}$.