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Dijet azimuthal correlations and conditional yields in pp and p+Pb collisions at sNN=5.02TeV with the ATLAS detector

Published version
Peer-reviewed

Type

Article

Change log

Authors

Aaboud, M 
Aad, G 
Abbott, B 
Abbott, DC 
Abdinov, O 

Abstract

This paper presents a measurement of forward-forward and forward-central dijet azimuthal angular correlations and conditional yields in proton-proton (pp) and proton-lead (p+Pb) collisions as a probe of the nuclear gluon density in regions where the fraction of the average momentum per nucleon carried by the parton entering the hard scattering is low. In these regions, gluon saturation can modify the rapidly increasing parton distribution function of the gluon. The analysis utilizes 25 pb−1 of pp data and 360 μb−1 of p+Pb data, both at sNN = 5.02 TeV, collected in 2015 and 2016, respectively, with the ATLAS detector at the LHC. The measurement is performed in the center-of-mass frame of the nucleon-nucleon system in the rapidity range between $-$4.0 and 4.0 using the two highest transverse momentum jets in each event, with the highest transverse momentum jet restricted to the forward rapidity range. No significant broadening of azimuthal angular correlations is observed for forward-forward or forward-central dijets in p+Pb compared to pp collisions. For forward-forward jet pairs in the proton-going direction, the ratio of conditional yields in p+Pb collisions to those in pp collisions is suppressed by approximately 20%, with no significant dependence on the transverse momentum of the dijet system. No modification of conditional yields is observed for forward-central dijets.

Description

Keywords

nucl-ex, nucl-ex, hep-ex

Journal Title

Physical Review C

Conference Name

Journal ISSN

2469-9985
2469-9993

Volume Title

100

Publisher

American Physical Society (APS)
Sponsorship
Science and Technology Facilities Council (ST/N000234/1)