Measurement of differential $J/\psi$ production cross-sections and forward-backward ratio in p+Pb collisions with the ATLAS detector

TL;DR

This paper reports measurements of differential $J/\psi$ production cross-sections and forward-backward ratios in proton-lead collisions at the LHC, providing insights into nuclear effects on charmonium and $b$-quark production.

Contribution

It presents the first detailed differential cross-section measurements and forward-backward ratios for $J/\psi$ in p+Pb collisions at 5.02 TeV, including separation of prompt and nonprompt sources.

Findings

Differential cross-sections measured for $8<p_T<30$ GeV and $-2.87<y^*<1.94$

Forward-backward ratios compared to theoretical models

Results constrain nuclear modification effects on charmonium and $b$-quark production

Abstract

Measurements of differential cross-sections for $J/\psi$ production in p+Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV at the LHC with the ATLAS detector are presented. The data set used corresponds to an integrated luminosity of 28.1 nb$^{-1}$. The $J/\psi$ mesons are reconstructed in the dimuon decay channel over the transverse momentum range $8<p_{\mathrm{T}}<30$ GeV and over the center-of-mass rapidity range $-2.87<y^{*}<1.94$. Prompt $J/\psi$ are separated from $J/\psi$ resulting from $b$-hadron decays through an analysis of the distance between the $J/\psi$ decay vertex and the event primary vertex. The differential cross-section for production of nonprompt $J/\psi$ is compared to a FONLL calculation that does not include nuclear effects. Forward-backward production ratios are presented and compared to theoretical predictions. These results constrain the kinematic dependence of nuclear modifications of charmonium and $b$-quark production in p+Pb collisions.