Central exclusive production of scalar and pseudoscalar charmonia in the light-front $k_T$-factorization approach

TL;DR

This paper investigates the exclusive production of scalar and pseudoscalar charmonia in proton-proton collisions at LHC energies using the light-front $k_T$-factorization approach, providing detailed predictions for various observables.

Contribution

It introduces the first calculation of the $pp o pp \, \eta_c$ reaction and compares the production mechanisms of $ ext{chi}_{c0}$ and $\\eta_c$ within the $k_T$-factorization framework.

Findings

The cross section for $\eta_c$ is significantly lower than for $\chi_{c0}$ in exclusive production.

Distinct correlation patterns are observed for $\chi_{c0}$ and $\eta_c$ in azimuthal and $(t_1,t_2)$ distributions.

The study highlights the impact of different vertices and UGDFs on the production rates.

Abstract

We study exclusive production of scalar $\chi_{c0}\equiv \chi_c(0^{++})$ and pseudoscalar $\eta_c$ charmonia states in proton-proton collisions at the LHC energies. The amplitudes for $gg \to \chi_{c0}$ as well as for $gg \to \eta_c$ mechanisms are derived in the $k_{T}$-factorization approach. The $p p \to p p \eta_c$ reaction is discussed for the first time. We have calculated rapidity, transverse momentum distributions as well as such correlation observables as the distribution in relative azimuthal angle and $(t_1,t_2)$ distributions. The latter two observables are very different for $\chi_{c0}$ and $\eta_c$ cases. In contrast to the inclusive production of these mesons considered very recently in the literature, in the exclusive case the cross section for $\eta_c$ is much lower than that for $\chi_{c0}$ which is due to a special interplay of the corresponding vertices and off-diagonal UGDFs used to calculate the cross sections. We present the numerical results for the key observables in the framework of potential models for the light-front quarkonia wave functions. We also discuss how different are the absorptive corrections for both considered cases.