Inclusive $\psi(2S)$ production at midrapidity in pp collisions at $\sqrt{s} = 13$ TeV

TL;DR

This paper reports the first measurement of inclusive $(2S)$ meson production at midrapidity in proton-proton collisions at 13 TeV, covering a broad transverse momentum range and comparing results with theoretical models.

Contribution

It provides the first measurement of $(2S)$ production at midrapidity in pp collisions at 13 TeV, extending the $p_T$ range and analyzing the $(2S)$-to-J/$$ ratio.

Findings

$(2S)$ production cross section measured for $4 < p_T < 16$ GeV/$c$.

A mild increase in the $(2S)$-to-J/$$ ratio with $p_T$ observed.

Results compared with NRQCD and ICEM theoretical predictions.

Abstract

Inclusive production of $\psi(2S)$ mesons is measured for the first time at midrapidity ($|y| < 0.9$) in pp collisions at $\sqrt{s} = 13$ TeV using the ALICE detector at the LHC. The measurement is performed in the transverse-momentum ($p_{\rm T}$) range of 4 to 16 GeV/$c$ and is based on events triggered by the Transition Radiation Detector, corresponding to an integrated luminosity of $1.7 \pm 1.8\%$ (syst.) pb$^{-1}$. The $p_{\rm T}$-differential production cross section of the $\psi(2S)$ and its ratio to the J/$\psi$ production cross section are presented. The results extend the accessible $p_{\rm T}$ range down to 4 GeV/$c$, and a mild rise of the $\psi(2S)$-to-J/$\psi$ cross section ratio with increasing $p_{\rm T}$ is observed. The measurements are compared with theoretical predictions based on NRQCD and the ICEM model.