Study of $\Upsilon$ production and cold nuclear matter effects in pPb collisions at $\sqrt{s_{NN}}=5~\mathrm{TeV}$

TL;DR

This study investigates $6$ meson production in proton-lead collisions at 5 TeV, revealing suppression in the forward region and enhancement in the backward region, providing insights into cold nuclear matter effects.

Contribution

It presents the first measurement of $6$ production and nuclear modification factors in pPb collisions at 5 TeV, highlighting cold nuclear matter effects on bottomonium production.

Findings

Suppression of $6$ in the forward region

Enhancement of $6$ in the backward region

Smaller suppression compared to prompt $J/2$

Abstract

Production of $\Upsilon$ mesons in proton-lead collisions at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{NN}}=5 \mathrm{TeV}$ is studied with the LHCb detector. The analysis is based on a data sample corresponding to an integrated luminosity of $1.6 \mathrm{nb}^{-1}$. The $\Upsilon$ mesons of transverse momenta up to $15 \mathrm{GeV}/c$ are reconstructed in the dimuon decay mode. The rapidity coverage in the centre-of-mass system is $1.5<y<4.0$ (forward region) and $-5.0<y<-2.5$ (backward region). The forward-backward production ratio and the nuclear modification factor for $\Upsilon(1S)$ mesons are determined. The data are compatible with the predictions for a suppression of $\Upsilon(1S)$ production with respect to proton-proton collisions in the forward region, and an enhancement in the backward region. The suppression is found to be smaller than in the case of prompt $J/\psi$ mesons.