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 mu+mu- 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 (p_T^(J/psi)) and rapidity (|y^(J/psi)|): |y^(J/psi)| lower than 1.2 for p_T^(J/psi) greater than 6.5 GeV/c; |y^(J/psi)| in [1.2,1.43] for a p_T threshold that scales linearly with |y^(J/psi)| from 6.5 to 4.5 GeV/c; and |y^(J/psi)| in [1.43,2.2] for p_T^(J/psi) greater than 4.5 GeV/c. 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%.
Measurement of prompt J/psi pair production in pp collisions at sqrt(s) = 7 TeV
CAVALLO, Nicola;FABOZZI, FRANCESCO;
2014-01-01
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 mu+mu- 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 (p_T^(J/psi)) and rapidity (|y^(J/psi)|): |y^(J/psi)| lower than 1.2 for p_T^(J/psi) greater than 6.5 GeV/c; |y^(J/psi)| in [1.2,1.43] for a p_T threshold that scales linearly with |y^(J/psi)| from 6.5 to 4.5 GeV/c; and |y^(J/psi)| in [1.43,2.2] for p_T^(J/psi) greater than 4.5 GeV/c. 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%.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
