Search for jet quenching with dijets from high-multiplicity pPb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV

Abstract

The first measurement of the dijet transverse momentum balance $x_j$ in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV is presented. The $x_j$ observable, defined as the ratio of the subleading over leading jet transverse momentum in a dijet pair, is used to search for jet quenching effects. The data, corresponding to an integrated luminosity of 174.6 nb${}^{-1}$, were collected with the CMS detector in 2016. The $x_j$ distributions and their average values are studied as functions of the charged-particle multiplicity of the events and for various dijet rapidity selections. The latter enables probing hard scattering of partons carrying distinct nucleon momentum fractions $x$ in the proton- and lead-going directions. The former, aided by the high-multiplicity triggers, allows probing for potential jet quenching effects in high-multiplicity events (with up to 400 charged particles), for which collective phenomena consistent with quark-gluon plasma (QGP) droplet formation were previously observed. The ratios of $x_j$ distributions for high- to low-multiplicity events are used to quantify the possible medium effects. These ratios are consistent with simulations of the hard-scattering process that do not include QGP production. These measurements set an upper limit on medium-induced energy loss of the subleading jet of 1.26% of its transverse momentum at the 90% confidence level in high multiplicity pPb events.

Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/HIN-23-010 (CMS Public Pages)

References in corpus (3)

• An Introduction to PYTHIA 8.2
• Description and performance of track and primary-vertex reconstruction with the CMS tracker
• Particle-level pileup subtraction for jets and jet shapes

Cited by in corpus (4)

• Observation of suppressed charged-particle production in ultrarelativistic oxygen-oxygen collisions
• Selection bias effects on high-$p_{\mathrm{T}}$ yield and correlation measurements in Oxygen+Oxygen collisions
• Geometric Bias and Centrality Dependence of Jet Quenching in High-Energy Nuclear Collisions
• System-size dependence of charged-particle suppression in ultrarelativistic nucleus-nucleus collisions