Measurement of inclusive jet cross sections in pp and PbPb collisions at $\sqrt{s _{NN}} =$ 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 CERN Large Hadron Collider, 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 $|\eta|<2$. Next-to-leading-order quantum chromodynamic calculations with nonperturbative corrections are found to overpredict 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.