Substructure dependence of jet cross sections at HERA and determination of alpha_s

TL;DR

This paper investigates jet substructure at HERA to distinguish quark and gluon jets, and uses jet shape measurements to precisely determine the strong coupling constant alpha_s(M_Z).

Contribution

It introduces a method to tag jets by substructure and extracts alpha_s(M_Z) with high precision from deep inelastic scattering data.

Findings

Jet substructure effectively tags quark and gluon jets.

Measured alpha_s(M_Z) aligns with world averages.

Cross sections follow expected parton dynamics.

Abstract

The substructure of jets has been studied in terms of the jet shape and subjet multiplicity and these quantities used to tag gluon- and quark-initiated jets. Cross sections are presented for gluon- and quark-tagged jets which exhibit the expected behaviour of the underlying parton dynamics. The value of alpha_s(M_Z) of alpha_s(M_Z) = 0.1176 +- 0.0009 (stat.) ^{+0.0009}_{-0.0026} (exp.) ^{+0.0091}_{-0.0072} (th.) was extracted from the measurements of jet shapes in deep inelastic scattering.