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Measurement of prompt J/ψ pair production in pp collisions at √s = 7 Tev

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journal contribution
posted on 01.09.2014, 00:00 authored by V. Khachatryan, A. M. Sirunyan, A. Tumasyan, V. Azzolini, A. Calamba, Thomas A. Ferguson, Yutaro Iiyama, Manfred PauliniManfred Paulini, James S. Russ, Helmut Vogel, Igor VorobievIgor Vorobiev, CMS Collaboration

Production of prompt J/ψ meson pairs in proton-proton collisions at s" role="presentation" style="border: 0px; font-variant: inherit; font-stretch: inherit; line-height: normal; font-family: inherit; margin: 0px; padding: 0px; vertical-align: baseline; outline: 0px; display: inline; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; position: relative;">s√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 fb−1. The two J/ψ mesons are fully reconstructed via their decays intoμ + 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 (p T J/ψ ) and rapidity (|y J/ψ |): |y J/ψ | < 1.2 for p T J/ψ > 6.5 GeV/c; 1.2 < |y J/ψ | < 1.43 for a p T threshold that scales linearly with |y J/ψ | from 6.5 to 4.5 GeV/c; and 1.43 < |y J/ψ | < 2.2 for p T J/ψ > 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%.

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Copyright CERN, for the benefit of the CMS Collaboration

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01/09/2014

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