Measurement of prompt J/psi pair production in pp collisions at sqrt(s) = 7 TeV

TL;DR

This paper reports the first measurement of prompt J/psi pair production at high transverse momentum in proton-proton collisions at 7 TeV, providing new data in a previously unexplored kinematic region.

Contribution

It presents the first measurement of prompt J/psi pair production at high transverse momentum in pp collisions at 7 TeV, expanding understanding of quarkonium production mechanisms.

Findings

Total cross section measured as 1.49 nb for unpolarized production.

Differential cross sections provided across various rapidity and transverse momentum ranges.

Polarization assumptions significantly affect the cross section estimates.

Abstract

Production of prompt J/psi meson pairs in proton-proton collisions at sqrt(s) = 7 TeV is measured with the CMS experiment at the LHC in a data sample corresponding to an integrated luminosity of about 4.7 inverse femtobarns. The two J/psi mesons are fully reconstructed via their decays into muon pairs. This observation provides for the first time access to the high-transverse-momentum region of J/psi pair production where model predictions are not yet established. The total and differential cross sections are measured in a phase space defined by the individual J/psi transverse momentum pt[J/psi] and rapidity abs(y[J/psi]): abs(y[J/psi]) < 1.2 for pt[J/psi] > 6.5 GeV; 1.2 < abs(y[J/psi]) < 1.43 for a pt threshold that scales linearly with abs(y[J/psi]) from 6.5 to 4.5 GeV; and 1.43 < abs(y[J/psi]) < 2.2 for pt[J/psi] > 4.5 GeV. The total cross section, assuming unpolarized prompt J/psi pair production is 1.49 +/- 0.07 (stat.) +/- 0.13 (syst.) nb. Different assumptions about the J/psi polarization imply modifications to the cross section ranging from -31% to +27%.