Particle Multiplicity in Jets and Sub-jets with Jet Axis from Color Current

TL;DR

This paper investigates particle multiplicity in jets and sub-jets using a jet axis derived from energy-multiplicity correlations, incorporating advanced QCD calculations to improve stability and accuracy in smaller jet cones.

Contribution

It generalizes previous calculations by including Modified LLA and Next-to-MLLA corrections, providing a more comprehensive analysis of multiplicities with a novel jet axis definition.

Findings

Multiplicity depends on the mean color current in the jet.

Effects of the jet axis definition are quantified for various jet angles and energies.

Inclusion of MLLA and NMLLA improves theoretical predictions.

Abstract

We study the particle multiplicity in a jet or sub-jet as derived from an energy-multiplicity 2-particle correlation. This definition avoids the notion of a globally fixed jet axis and allows for the study of smaller jet cone openings in a more stable way. The results are sensitive to the mean color current $<C >_{A_0} $ in the jet from primary parton $A_0$ which takes into account intermediate partonic processes in the sub-jet production where $C_F< < C >_{A_0} < N_c$ at high energies. We generalize previous calculations in Leading Logarithmic Approximation (LLA). The size of the effects related to this jet axis definition are computed for multiplicities in sub-jets with different opening angles and energies by including contributions from the Modified LLA (MLLA) and Next-to-MLLA to the leading order QCD results.