Production of two $J/\psi$ mesons in proton-proton collisions at the LHC

TL;DR

This paper analyzes the production mechanisms of two $J/$ mesons in proton-proton collisions at the LHC, including single and double parton contributions, higher-order exchanges, and feed-down effects, relevant for current experimental observations.

Contribution

It introduces a comprehensive model that combines multiple production mechanisms of $J/$ pairs, emphasizing the importance of higher-order and feed-down contributions at large rapidity separations.

Findings

Double-parton scattering significantly contributes to $J/$ pair production.

Higher-order two-gluon exchange impacts large rapidity gap events.

Feed-down from $_c$ states influences observed $J/$ yields.

Abstract

We discuss inclusive production of pairs of $J/\psi$ quarkonia. Both leading-order single parton (box) contribution and double-parton contributions are included. In addition we discuss a contribution of higher-order two-gluon exchange and a feed down from double $\chi_c$ production. The second two contributions are important for large rapidity distance between the two $J/\psi$ mesons and for relatively large cut-offs on quarkonia transverse momenta. A relation to current experiments is discussed.