Measurement of the relative rate of prompt $\chi_{c0}$, $\chi_{c1}$ and $\chi_{c2}$ production at $\sqrt{s}=7$TeV

TL;DR

This paper measures the production rates of different $ ext{chi}_c$ mesons in proton-proton collisions at 7 TeV, providing new insights into charmonium production mechanisms at high energies.

Contribution

It presents the first evidence for $ ext{chi}_c0$ production at a high-energy hadron collider and measures the relative prompt production rates of $ ext{chi}_c1$ and $ ext{chi}_c2$ as a function of $J/\psi$ transverse momentum.

Findings

First evidence for $ ext{chi}_c0$ production at a collider.

Measured relative production rates of $ ext{chi}_c1$ and $ ext{chi}_c2$.

Provided data on $ ext{chi}_c$ production as a function of $J/\psi$ $p_T$.

Abstract

Prompt production of charmonium $\chi_{c0}$, $\chi_{c1}$ and $\chi_{c2}$ mesons is studied using proton-proton collisions at the LHC at a centre-of-mass energy of $\sqrt{s}=7$TeV. The $\chi_{c}$ mesons are identified through their decay to $J/\psi\gamma$, with $J/\psi\to\mu^+\mu^-$ using photons that converted in the detector. A data sample, corresponding to an integrated luminosity of $1.0\mathrm{fb}^{-1}$ collected by the LHCb detector, is used to measure the relative prompt production rate of $\chi_{c1}$ and $\chi_{c2}$ in the rapidity range $2.0<y<4.5$ as a function of the $J/\psi$ transverse momentum from 3 to 20 GeV$/c$. First evidence for $\chi_{c0}$ meson production at a high-energy hadron collider is also presented.