Measurement of the jet fragmentation function and transverse profile in proton-proton collisions at a center-of-mass energy of 7 TeV with the ATLAS detector

TL;DR

This paper presents measurements of the jet fragmentation function and transverse profile in proton-proton collisions at 7 TeV using the ATLAS detector, comparing results with Monte Carlo simulations to evaluate their accuracy.

Contribution

It provides the first detailed measurement of jet fragmentation and transverse profiles at 7 TeV, highlighting discrepancies with existing Monte Carlo models.

Findings

Some Monte Carlo tunes agree with the fragmentation function

No model reproduces both transverse profile and fragmentation function fully

Results improve understanding of jet structure in high-energy collisions

Abstract

The jet fragmentation function and transverse profile for jets with 25 GeV < ptJet < 500 GeV and etaJet<1.2 produced in proton-proton collisions with a center-of-mass energy of 7 TeV are presented. The measurement is performed using data with an integrated luminosity of 36 pb^-1. Jets are reconstructed and their momentum measured using calorimetric information. The momenta of the charged particle constituents are measured using the tracking system. The distributions corrected for detector effects are compared with various Monte Carlo event generators and generator tunes. Several of these choices show good agreement with the measured fragmentation function. None of these choices reproduce both the transverse profile and fragmentation function over the full kinematic range of the measurement.