4th International Conference on the Initial Stages in High-Energy Nuclear Collisions

Measurement of the fragmentation function for photon-tagged jets in 5.02 TeV Pb+Pb and pp collisions with the ATLAS detector

Not scheduled

2h

Karolina Lanckorońska Hall (catering during the poster session in the PAU’s courtyard)

POSTER SESSION

Speakers

ATLAS Collaboration Dennis Perepelitsa (University of Colorado Boulder)

Description

A measurement of the charged-particle fragmentation function (FF) for
jets azimuthally balanced by a high transverse momentum (pT) prompt,
isolated photon is presented. FFs as a function of particle-pT and
fraction of the jet pT carried by the particle, z, are measured in
26/pb of pp and 0.49/nb of Pb+Pb collision data at 5.02 TeV recorded
with the ATLAS detector. In pp collisions, a comparison of the
photon-tagged jet FF to that for inclusively selected jets is
sensitive to the difference in fragmentation between quark— and
gluon--initiated jets in vacuum. The ratio of the FF in Pb+Pb events
to those in pp events with the same selection on the photon kinematic
variables provides information on the modification of the parton
shower for quark-initiated jets as they traverse the hot nuclear
medium. In comparison to the modified FF for inclusively-selected
jets, photon-tagged jets show a similar modification in particle-pT or
z in semi-central and peripheralevents, but a stronger one in central
events.