Khachatryan V.; Sirunyan A. M.; Tumasyan A.; Abdulsalam, A.; Dutta, D.; Kailas, S.; Kumar, V.; Mohanty, A. K.; Pant, L. M.; Shukla, P.; Topkar, A.; and others (NPD)
Source
Journal of High Energy Physics, 2014. Vol. 9: Article no. 094
ABSTRACT
Production of prompt J/Ψ meson pairs in proton-proton collisions at √s =7TeV is measured with the CMS experiment at the LHC in a data sample corresponding to an integrated luminosity of about 4.7 fb−1. The two J/Ψ mesons are fully reconstructed via their decays into μ+μ− pairs. This observation provides for the first time access to the high-transverse-momentum region of J/Ψ 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/Ψ transverse momentum (pTJ/Ψ ) and rapidity (|yJ/Ψ |): |yJ/Ψ | < 1.2 for pJ/ΨT > 6.5 GeV/c; 1.2 < |yJ/Ψ | < 1.43 for a pT threshold that scales linearly with |yJ/Ψ | from 6.5 to 4.5 GeV/c; and 1.43 < |yJ/Ψ | < 2.2 for pJ/Ψ T > 4.5 GeV/c. The total cross section, assuming unpolarized prompt J/Ψ pair production is 1.49 ± 0.07 (stat) ± 0.13 (syst) nb. Different assumptions about the J/Ψ polarization imply modifications to the cross section ranging from −31% to +27%.