Measurement of inclusive jet cross sections in pp and PbPb collisions at sNN=2.76 TeV

Abstract

Inclusive jet spectra from pp and PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV, collected with the CMS detector at the LHC, are presented. Jets are reconstructed with three different distance parameters (R = 0.2, 0.3 and 0.4) for transverse momentum (p T ) greater than 70 GeV/c and pseudorapidity |η| < 2. Next-toleading-order quantum chromodynamic calculations with non-perturbative corrections are found to over-predict jet production cross sections in pp for small distance parameters. The jet nuclear modification factors for PbPb compared to pp collisions, show a steady decrease from peripheral to central events, along with a weak dependence on the jet p T . They are found to be independent of the distance parameter in the measured kinematic range.

Phenomenology of single-inclusive jet production with jet radius and threshold resummation

“…Other data sets, such as those by CMS collected at ffiffiffi S p ¼ 2.76 TeV [15] and the one ATLAS at ffiffiffi S p ¼ 13 TeV [21] have already been considered in [27].…”

“…Specifically, ALICE [13], ATLAS [14] and CMS [15] have collected data at ffiffiffi S p ¼ 2.76 TeV and ATLAS and CMS at ffiffiffi S p ¼ 7 TeV [16,17], 8 TeV [18,19] and 13 TeV [20][21][22]. These data allow for important consistency tests of pQCD as well as a precise extraction of the value of the strong coupling constant α s ðM Z Þ [23], and they provide very valuable constraints on parton distribution functions (PDFs) which govern the parton luminosity of the colliding initial protons [24,25].…”

Comparison of Fragmentation Functions for Jets Dominated by Light Quarks and Gluons from pp and Pb+Pb Collisions in ATLAS

“…The high density of unscreened color charges causes hard-scattered partons with large transverse momentum (p T ) to lose energy as they traverse the medium, a phenomenon referred to as jet quenching. In lead-lead (Pb+Pb) collisions at the Large Hadron Collider (LHC), jet production rates at fixed p T are suppressed relative to proton-proton (pp) collisions [1][2][3][4]. Since the parton shower develops inside the quark-gluon plasma, the momentum distributions of hadrons in the quenched jet are also modified.…”

Inclusive jet measurements in pp and Pb--Pb collisions with ALICE

“…Jets traverse a significant pathlength of the medium, and the effect that the medium has on jets can be deduced by comparing jet properties in heavy-ion collisions to those in pp collisions. Previous measurements demonstrate suppression of the jet transverse momentum (p T ) spectrum in heavy-ion collisions, indicating that jets transfer energy to the hot QCD medium [1,2,3,4]. However, the basic nature of this deconfined QCD state remains largely unknown.…”