Abstract
A measurement of the fragmentation functions of jets into charged particles in p+Pb collisions and pp collisions is presented. The analysis utilizes 28 nb−1 of p+Pb data and 26 pb−1 of pp data, both at sNN= 5.02 TeV, collected in 2013 and 2015, respectively, with the ATLAS detector at the LHC. The measurement is reported in the centre-of-mass frame of the nucleon–nucleon system for jets in the rapidity range |y⁎|<1.6 and with transverse momentum 45 <pT< 260 GeV. Results are presented both as a function of the charged-particle transverse momentum and as a function of the longitudinal momentum fraction of the particle with respect to the jet. The pp fragmentation functions are compared with results from Monte Carlo event generators and two theoretical models. The ratios of the p+Pb to pp fragmentation functions are found to be consistent with unity.
Highlights
Heavy-ion collisions at the Large Hadron Collider (LHC) are performed in order to produce and study the quark–gluon plasma (QGP), a phase of strongly interacting matter which emerges at very high energy densities; a recent review can be found in Ref. [1]
PYTHIA version 6.423 (PYTHIA6) agrees within approximately 25% when compared to the data and HERWIG++ agrees within approximately 20% except for the highest z region, where there are some larger deviations
This paper presents the first measurement of the jet charged-particle fragmentation functions in a p + A |yj∗et| < 1.6
Summary
Heavy-ion collisions at the Large Hadron Collider (LHC) are performed in order to produce and study the quark–gluon plasma (QGP), a phase of strongly interacting matter which emerges at very high energy densities; a recent review can be found in Ref. [1]. The ATLAS Collaboration / Nuclear Physics A 978 (2018) 65–106 reference system Using this reference, rates of jet production in Pb + Pb collisions are observed to be reduced compared to that expected from the rates in pp collisions, appropriately scaled to account for the nuclear thickness in Pb + Pb collisions [2,3]. Charged-particle fragmentation functions are observed to be modified in Pb + Pb collisions compared to pp collisions [4,5,6]. Both of these effects are interpreted as arising predominantly from the modification of the parton showering process in the final stages of the collision
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