Complete Nonrelativistic-QCD Prediction for Prompt Double $J/\psi$ Hadroproduction

TL;DR

This paper provides a comprehensive leading-order nonrelativistic-QCD calculation for prompt double $J/$ hadroproduction, including all relevant Fock state pairings, and shows that previously overlooked channels significantly improve agreement with experimental data.

Contribution

It introduces a complete leading-order NRQCD prediction for double $J/$ production by including all relevant Fock state pairings, filling gaps in prior models.

Findings

Overlooked channels dominate at large invariant masses and rapidity separations.

Inclusion of these channels nearly explains experimental measurements.

Next-to-leading-order corrections are expected to further refine predictions.

Abstract

We perform a complete study of prompt double $J/\psi$ hadroproduction at leading order in the nonrelativistic-QCD factorization framework by including all possible pairings of the $c\bar{c}$ Fock states ${}^1\!S_0^{[8]}$, ${}^3\!S_1^{[1,8]}$, and ${}^3\!P_J^{[1,8]}$ with $J=0,1,2$. We find that the ${}^1\!S_0^{[8]}$ and ${}^3\!P_J^{[8]}$ channels of $J/\psi$ and $\psi^\prime$ production and the ${}^3\!P_J^{[1]}$ and ${}^3\!S_1^{[8]}$ channels of $\chi_{cJ}$ production, which have been overlooked so far, greatly dominate at large invariant masses and rapidity separations of the $J/\psi$ pair, and that their inclusion nearly fills the large gap between previous incomplete predictions within the color-singlet model and the recent measurement by the CMS Collaboration at the CERN LHC, leaving room for next-to-leading-order corrections of typical size.