Study of Direct Single Photons and Correlated Particles in Proton-proton Collisions At. Sqrt. S

Study of Direct Single Photons and Correlated Particles in Proton-proton Collisions At. Sqrt. S
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Release: 1980
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As part of a study of large p/sub T/ phenomena in proton-proton collisions at the CERN ISR, a search for direct single photon production has been performed. A statistical division of the data sample into the fraction consistent with single photon production and the fraction due to multiphoton decays of neutral hadrons is accomplished by measuring the average conversion probability for the sample in a one radiation length thick converter. The fraction of the sample attributable to direct single photon production is .gamma./all = 0.074 +- 0.012 for 6 GeV/c = 0.26 +- 0.04 for p/sub T/> 10 GeV/c, with an additional systematic uncertainty of +- 0.05 for both values. It is found that single photons are produced preferentially with no accompanying particles on the same side. The ratio of positive to negative particles on the away side is found to be 3.7 +- 1.2 at high x/sub E/ and p/sub T/ for the single photon events.

J/psi and Psi(2S) Production in Pp Collisions at Sqrt(s)

J/psi and Psi(2S) Production in Pp Collisions at Sqrt(s)
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Total Pages: 39
Release: 2012
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A measurement of the J/psi and psi(2S) production cross sections in pp collisions at sqrt(s)=7 TeV with the CMS experiment at the LHC is presented. The data sample corresponds to an integrated luminosity of 37 inverse picobarns. Using a fit to the invariant mass and decay length distributions, production cross sections have been measured separately for prompt and non-prompt charmonium states, as a function of the meson transverse momentum in several rapidity ranges. In addition, cross sections restricted to the acceptance of the CMS detector are given, which are not affected by the polarization of the charmonium states. The ratio of the differential production cross sections of the two states, where systematic uncertainties largely cancel, is also determined. The branching fraction of the inclusive B to psi(2S) X decay is extracted from the ratio of the non-prompt cross sections to be: BR(B to psi(2S) X) = (3.08 +/- 0.12(stat.+syst.) +/- 0.13(theor.) +/- 0.42(BR[PDG])) 10-̂3.

Inclusive B-jet Production in Pp Collisions at Sqrt(s)

Inclusive B-jet Production in Pp Collisions at Sqrt(s)
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Total Pages: 33
Release: 2012
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The inclusive b-jet production cross section in pp collisions at a center-of-mass energy of 7 TeV is measured using data collected by the CMS experiment at the LHC. The cross section is presented as a function of the jet transverse momentum in the range 18