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, $z \equiv p_{\rm T}(J/ψ)/p_{\rm T}({\rm jet})$, is measured using jets with $p_{\rm T}({\rm jet}) > 20$ GeV in the pseudorapidity range $2.5 < η({\rm jet}) < 4.0$. The observed $z$ 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 non-relativistic QCD. This is the first measurement of the $p_{\rm T}$ fraction carried by prompt $J/ψ$ mesons in jets at any experiment.

All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-064.html; v2 updated to journal version