Particle Ratios at High Transverse Momentum in Pp Collisions At. Sqrt. S
Particle Ratios at High Transverse Momentum in Pp Collisions At. Sqrt. S

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Published: 1983

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The production of identified charged particles in pp collisions at .sqrt.s = 63 GeV with an identified high p/sub T/ trigger particle emitted in the central region is studied. The measurements were performed at the CERN ISR using the Axial Field Spectrometer. Trigger particle ratios, sigma(.pi./sup + -/)/ sigma(all/sup + -/), sigma(K/sup + -/) and sigma(p/sup + -/)/sigma(all/sup + -/) are presented for p/sub T/ from 5 GeV/c to 8 GeV/c. In addition sigma(.pi./sup + -/)/sigma(all/sup + -/) is presented in the p/sub T/ region from 2.5 GeV/c to 4.5 GeV/c. The charge compensation in the hemisphere containing the trigger particle is shown to depend strongly on the identity of the trigger particle and on the identity of the associated particles. 13 references.

Charged Particle Transverse Momentum Spectra in Pp Collisions at Sqrt(s)
Charged Particle Transverse Momentum Spectra in Pp Collisions at Sqrt(s)

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Published: 2011

Total Pages: 36

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The charged particle transverse momentum (pT) spectra are presented for pp collisions at sqrt(s)=0.9 and 7 TeV. The data samples were collected with the CMS detector at the LHC and correspond to integrated luminosities of 231 inverse microbarns and 2.96 inverse picobarns, respectively. Calorimeter-based high-transverse-energy triggers are employed to enhance the statistical reach of the high-pT measurements. The results are compared with both leading-order QCD and with an empirical scaling of measurements at different collision energies using the scaling variable xT = 2 pT/sqrt(s) over the pT range up to 200 GeV/c. Using a combination of xT scaling and direct interpolation at fixed pT, a reference transverse momentum spectrum at sqrt(s)=2.76 TeV is constructed, which can be used for studying high-pT particle suppression in the dense QCD medium produced in heavy-ion collisions at that centre-of-mass energy.

J/psi Production at High Transverse Momenta in P+p and Cu+Cu Collisions at Sqrt SNN
J/psi Production at High Transverse Momenta in P+p and Cu+Cu Collisions at Sqrt SNN

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Published: 2009

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The STAR collaboration at RHIC presents measurements of J/[psi] → e+e− at mid-rapidity and high transverse momentum (p{sub T} > 5 GeV/c) in p+p and central Cu+Cu collisions at √sNN = 200 GeV. The inclusive J/[psi] production cross section for Cu+Cu collisions is found to be consistent at high p{sub T} with the binary collision-scaled cross section for p+p collisions, in contrast to previous measurements at lower p{sub T}, where a suppression of J/[psi] production is observed relative to the expectation from binary scaling. Azimuthal correlations of J/[psi] with charged hadrons in p+p collisions provide an estimate of the contribution of B-meson decays to J/[psi] production of 13% ± 5%.