Jet transverse fragmentation momentum from h-h correlations in pp and p-Pb collisions

TL;DR

This study analyzes jet fragmentation in pp and p-Pb collisions using two-particle correlations to distinguish between perturbative branching and non-perturbative hadronization effects, finding consistent results across collision types and comparing with PYTHIA8 simulations.

Contribution

It presents a differential analysis of jet transverse fragmentation momentum components, separating branching and hadronization, using ALICE data and comparing with PYTHIA8 simulations.

Findings

Hadronization component is flat across pTt, supporting universality.

Branching component shows a slight increase with pTt.

No significant difference between pp and p-Pb results within errors.

Abstract

QCD color coherence phenomena, like angular ordering, can be studied by looking at jet fragmentation. As the jet is fragmenting, it is expected to go through two different phases. First, there is QCD branching that is calculable in perturbative QCD. Next, the produced partons hadronize in a non-perturbative way later in a hadronization process. The jet fragmentation can be studied using the method of two particle correlations. A useful observable is the jet transverse fragmentation momentum $j_{\mathrm{T}}$, which describes the angular width of the jet. In this contribution, a differential study will be presented in which separate $j_{\mathrm{T}}$ components for branching and hadronization will be distinguished from the data measured by the ALICE experiment. The $p_{\mathrm{Tt}}$ dependence of the hadronization component $\sqrt{\left<j_{\mathrm{T}}^{2}\right>}$ is found to be rather flat, which is consistent with universal hadronization assumption. However, the branching component shows slightly rising trend in $p_{\mathrm{Tt}}$. The $\sqrt{s} = 7\,\mathrm{TeV}$ pp and $\sqrt{s_{\mathrm{NN}}} = 5.02\,\mathrm{TeV}$ p-Pb data give the same results within error bars, suggesting that this observable is not affected by cold nuclear matter effects in p-Pb collisions. The measured data will also be compared to the results obtained from PYTHIA8 simulations.