Inclusive prompt $\chi_{c,b}(1^{++})$ production at the LHC

TL;DR

This paper investigates the production mechanisms of $ ext{chi}_c(1^+)$ and $ ext{chi}_b(1^+)$ mesons at the LHC, focusing on processes beyond the leading order due to the forbidden LO gluon fusion, and compares theoretical predictions with experimental data.

Contribution

The study introduces and analyzes four alternative production mechanisms for $ ext{chi}(1^+)$ mesons, expanding understanding of their prompt production at high energies.

Findings

Standard NLO process $gg\to\chi_{c,b}(1^+)+g$ contributes significantly.

Gluon virtuality and reggeization provide additional production channels.

Three-gluon fusion via parton cascades can produce $ ext{chi}(1^+)$ mesons.

Abstract

We study the prompt production of the $\chi_c(1^+)$ and $\chi_b(1^+)$ mesons at high energies. Unlike $\chi(0^+,2^+)$ production, $\chi (1^+)$ mesons cannot be created at LO via the fusion of two on-mass-shell gluons, that is $gg\to\chi_{c,b}(1^+)$ are not allowed. However, the available experimental data show that the cross sections for $\chi_c(1^+)$ and $\chi_c(2^+)$ are comparable. We therefore investigate four other $\chi(1^+)$ production mechanisms: namely, (i) the standard NLO process $gg\to\chi_{c,b}(1^+)+g$, (ii) via gluon virtuality, (iii) via gluon reggeization and, finally, (iv) the possibility to form $\chi_{c,b}(1^+)$ by the fusion of three gluons, where one extra gluon comes from another parton cascade, as in the Double Parton Scattering processes.