CMS-BPH-15-003
Study of J/ψ meson production from jet fragmentation in pp collisions at √s= 8 TeV
A study of the production of prompt J/ψ mesons as fragmentation products of jets in proton-proton collisions at s√= 8 TeV is presented. The analysis is based on data corresponding to an integrated luminosity of 19.1 fb−1 collected with the CMS detector at the LHC. For events with at least one observed jet, the angular separation between the J/ψ meson and the jet is used to test whether the J/ψ meson is a jet fragment. The analysis shows that most prompt J/ψ mesons with energy above 15 GeV and rapidity |y|< 1 are fragments of jets with pseudorapidity |ηjet|< 1. The differential distributions of the jet fragmentation probability as a function of jet energy for a fixed J/ψ energy fraction are compared to a theoretical model using the fragmenting jet function approach. The data agree best with fragmenting jet function calculations that use a long-distance matrix element parameter set in which prompt J/ψ mesons are unpolarized. This technique demonstrates a new way to test predictions for prompt J/ψ production using nonrelativistic quantum chromodynamics.