A perturbative QCD study of dijets in p+Pb collisions at the LHC

摘要

Inspired by the recent measurements of the CMS collaboration, we report a QCDstudy of dijet production in proton+lead collisions at the LHC involvinglarge-transverse-momentum jets, $p_T \gtrsim 100$ GeV. Examining the inherentuncertainties of the next-to-leading order perturbative QCD calculations andtheir sensitivity to the free proton parton distributions (PDFs), we observe arather small, typically much less than 5% clearance for the shape of the dijetrapidity distribution within approximately 1.5 units around the midrapidity.Even a more stable observable is the ratio between the yields in the positiveand negative dijet rapidity, for which the baseline uncertainty can be madenegligible by imposing a symmetric jet rapidity acceptance. Both observablesprove sensitive to the nuclear modifications of the gluon distributions, thecorresponding uncertainties clearly exceeding the estimated baselineuncertainties from the free-proton PDFs and scale dependence. From atheoretical point of view, these observables are therefore very suitable fortesting the validity of the collinear factorization and have a high potentialto provide precision constraints for the nuclear PDFs.