Prompt double $J/\psi$ production in proton-proton collisions at the LHC

TL;DR

This paper studies prompt double $J/\psi$ production at the LHC within the NRQCD framework, comparing theoretical predictions with recent experimental data, and explores the potential for higher-order corrections and correlations.

Contribution

It provides a detailed comparison of LO NRQCD predictions with LHC data, highlighting discrepancies and the need for higher-order corrections, and investigates rapidity correlations in double $J/\psi$ production.

Findings

LHCb data aligns with $k_T$-factorized LO NRQCD results.

CMS data shows about one order of magnitude discrepancy with LO NRQCD.

No ridge-like structure observed in double $J/\psi$ correlations.

Abstract

We provide a detailed study of prompt double $J/\psi$ production within the non-relativistic QCD (NRQCD) framework in proton-proton collisions at the LHC. We confront the recent LHC data with the results obtained at leading-order (LO) in the NRQCD framework within two approaches of the collinear factorization and the $k_T$-factorization. We show that the LHCb data are consistent with the $k_T$-factorized LO NRQCD results. We show that the full LO NRQCD formalism cannot describe the recent CMS data, with about one order of magnitude discrepancy. If the CMS data are confirmed, this indicates rather large higher-order corrections for prompt double $J/\psi$ production. We provide various predictions which can further test the NRQCD-based approach at the LHC in a kinematic region that LO contributions dominate. We also investigate long-range in rapidity double $J/\psi$ correlations. We found no evidence of a ridge-like structure for double $J/\psi$ production in proton-proton collisions at the LHC up to subleading $\alpha_s^6$ accuracy.