Study of J/ψ Production in Jets

Abstract

The production of J /ψ mesons in jets is studied in the forward region of proton-proton collisions using data collected with the LHCb detector at a center-of-mass energy of 13 TeV. The fraction of the jet transverse momentum carried by the J /ψ meson, z (J /ψ ) ≡pT(J /ψ )/pT(jet ) , is measured using jets with pT(jet )>20 GeV in the pseudorapidity range 2.5 <η (jet )<4.0 . The observed z (J /ψ ) distribution for J /ψ mesons produced in b -hadron decays is consistent with expectations. However, the results for prompt J /ψ production do not agree with predictions based on fixed-order nonrelativistic QCD. This is the first measurement of the pT fraction carried by prompt J /ψ mesons in jets at any experiment.