A Monte Carlo study of jet fragmentation functions in PbPb and pp collisions at sqrt{s}=2.76 TeV

TL;DR

This study uses Monte Carlo simulations to analyze how jet fragmentation functions differ in PbPb and pp collisions at 2.76 TeV, comparing medium-modified and vacuum scenarios to experimental data.

Contribution

It introduces a detailed Monte Carlo analysis of medium effects on jet fragmentation functions, comparing two different modeling scenarios with experimental results.

Findings

Medium modifications are better described by the virtuality transfer scenario.

Simulations qualitatively match experimental FF shapes and features.

Ratios of FFs favor the virtuality transfer model.

Abstract

The parton-to-hadron fragmentation functions (FFs) obtained from the YaJEM and PYTHIA6 Monte Carlo event generators, are studied for jets produced in a strongly-interacting medium and in the QCD "vacuum" respectively. The medium modifications are studied with the YaJEM code in two different scenarios by (i) accounting for the medium induced virtuality DeltaQ^2 transferred to the leading parton from the medium, and (ii) by altering the infrared sector in the Borghini-Wiedemann approach. The results of our simulations are compared to experimental jet data measured by the CMS experiment in PbPb and pp collisions at a center-of-mass energy of 2.76 TeV. Though both scenarios qualitatively describe the shape and main physical features of the FFs, the ratios are in much better agreement with the first scenario. Results are presented for the Monte Carlo FFs obtained for different parton flavours (quark and gluon) and accounting exactly, or not, for the experimental jet reconstruction biases.