Dijet azimuthal correlations and conditional yields in pp and p+Pb collisions at q SNN = 5.02 TeV with the atlas detector

This dissertation 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 for possible gluon-density saturation in regions where the momentum fraction of a parton compared to a nucleon in the lead nucleus 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 μ b^-1 of $p$+Pb data, both at \sqrt{s_NN} = 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 center-of-mass rapidity range between -4.0 and 4.0 using the two highest transverse momentum jets in each event. The highest transverse momentum jet is restricted to the forward rapidity range where it is possible to probe the region where the momentum fraction of a parton compared to a nucleon in the lead nucleus is low. No significant broadening of azimuthal angular correlations is observed for forward--forward or forward--central dijets in $p$+Pb compared to $pp$ collisions within the uncertainties. The ratio of conditional yields of forward--forward jet pairs in the proton-going direction in $p$+Pb collisions compared to $pp$ collisions is suppressed by approximately 20\%, with no significant dependence on the transverse momentum of the dijets system. No modification of conditional yields is observed for forward--central dijets.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2019

Author dc:creator

• Kulinich, Yakov

Contributors dc:contributor

• Grosse Perdekamp, Matthias
• Sickles, Anne M
• Yang, Liang
• Willenbrock, Scott
• Bezryadin, Alexey

• nuclear physics, proton structure

Statement dc:rights

• Copyright 2018 Yakov Kulinich

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/102417

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F102417