Charmonia production in p+p collisions under NRQCD formalism

TL;DR

This paper calculates charmonia production cross sections in high-energy p+p collisions using NRQCD, fitting LDMEs to experimental data and successfully describing the observed distributions across various energies.

Contribution

It applies the NRQCD formalism to describe charmonia production in p+p collisions, fitting LDMEs from data and predicting cross sections at LHC energies.

Findings

NRQCD formalism accurately describes charmonia production data

LDMEs fitted from experimental transverse momentum distributions

Predictions made for LHC energies at 13 and 5 TeV

Abstract

This work presents the differential charmonia production cross sections in high energy p+p collisions calculated using NRQCD formalism. The NRQCD formalism, factorizes the quarkonia production cross sections in terms of short distance QCD cross sections and long distance matrix elements (LDMEs). The short distance cross sections are calculated in terms of perturbative QCD and LDMEs are obtained by fitting the experimental data. Measured transverse momentum distributions of $\chi_{\rm c}$, $\psi$(2S) and J/$\psi$ in p +{$\bar {\rm p}$} collisions at $\sqrt{s}=$ 1.8, 1.96 TeV and in p+p collisions at $\sqrt{s}=$ 7, 8 and 13 TeV are used to constrain LDMEs. The feed-down contribution to each state from the higher states are taken into account. The formalism provides a very good description of the data in a wide energy range. The values of LDMEs are used to predict the charmonia cross sections in p+p collisions at 13 and 5 TeV in kinematic bins relevant for the LHC detectors.