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Träfflista för sökning "WFRF:(Kweon SS) srt2:(2005-2009)"

Sökning: WFRF:(Kweon SS) > (2005-2009)

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1.
  • Adcox, K, et al. (författare)
  • Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX Collaboration
  • 2005
  • Ingår i: Nuclear Physics, Section A. - : Elsevier. - 0375-9474. ; 757:1-2, s. 184-283
  • Forskningsöversikt (refereegranskat)abstract
    • Extensive experimental data from high-energy nucleus-nucleus collisions were recorded using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). The comprehensive set of measurements from the first three years of RHIC operation includes charged particle multiplicities, transverse energy, yield ratios and spectra of identified hadrons in a wide range of transverse momenta (PT), elliptic flow, two-particle correlations, nonstatistical fluctuations, and suppression of particle production at high PT. The results are examined with an emphasis on implications for the formation of a new state of dense matter. We find that the state of matter created at RHIC cannot be described in terms of ordinary color neutral hadrons.
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3.
  • Adler, SS, et al. (författare)
  • Common suppression pattern of eta and pi(0) mesons at high transverse momentum in Au plus Au collisions at root SNN=200 GeV
  • 2006
  • Ingår i: Physical Review Letters. - : American Physical Society. - 1079-7114. ; 96:20
  • Tidskriftsartikel (refereegranskat)abstract
    • Inclusive transverse momentum spectra of eta mesons have been measured within p(T)=2-10 GeV/c at midrapidity by the PHENIX experiment in Au+Au collisions at root s(NN) = 200 GeV. In central Au+Au the eta yields are significantly suppressed compared to peripheral Au+Au, d+Au, and p+p yields scaled by the corresponding number of nucleon-nucleon collisions. The magnitude, centrality, and p(T) dependence of the suppression is common, within errors, for eta and pi(0). The ratio of eta to pi(0) spectra at high p(T) amounts to 0.40 < R-eta/pi(0)< 0.48 for the three systems, in agreement with the world average measured in hadronic and nuclear reactions and, at large scaled momentum, in e(+)e(-) collisions.
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4.
  • Adler, SS, et al. (författare)
  • Deuteron and antideuteron production in Au+Au collisions at root s(NN)=200 GeV
  • 2005
  • Ingår i: Physical Review Letters. - : American Physical Society. - 1079-7114. ; 94:12
  • Tidskriftsartikel (refereegranskat)abstract
    • The production of deuterons and antideuterons in the transverse momentum range 1.1 < p(T)< 4.3 GeV/c at midrapidity in Au+Au collisions at root s(NN) = 200 GeV has been studied by the PHENIX experiment at RHIC. A coalescence analysis, comparing the deuteron and antideuteron spectra with that of proton and antiproton, has been performed. The coalescence probability is equal for both deuterons and antideuterons and it increases as a function of p(T), which is consistent with an expanding collision zone. Comparing (anti)proton yields, (p) over bar /p = 0.73 +/- 0.01, with (anti)deuteron yields, (d) over bar /d = 0.47 +/- 0.03, we estimate that (n) over bar /n = 0.64 +/- 0.04. The nucleon phase space density is estimated from the coalescence measurement.
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6.
  • Adler, SS, et al. (författare)
  • Measurement of single electron event anisotropy in Au plus Au collisions at root s(NN)=200 GeV
  • 2005
  • Ingår i: Physical Review C (Nuclear Physics). - : American Physical Society. - 0556-2813. ; 72:2
  • Tidskriftsartikel (refereegranskat)abstract
    • The transverse momentum dependence of the azimuthal anisotropy parameter v(2), the second harmonic of the azimuthal distribution, for electrons at midrapidity (vertical bar eta vertical bar < 0.35) has been measured with the PHENIX detector in Au+Au collisions at root s(NN) = 200 GeV. The measurement was made with respect to the reaction plane defined at high rapidities (vertical bar eta vertical bar = 3.1-3.9). From the result we have measured the v(2) of electrons from heavy flavor decay after subtraction of the v(2) of electrons from other sources such as photon conversions and Dalitz decay from light neutral mesons. We observe a nonzero single electron v(2) with a 90% confidence level in the intermediate-p(T) region. The precision of the present data set does not permit us to conclude definitively that heavy quarks exhibit thermalization with the transverse flow of the bulk matter.
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7.
  • Adler, SS, et al. (författare)
  • Measurement of transverse single-spin asymmetries for midrapidity production of neutral pions and charged hadrons in polarized p+p collisions at root s=200 GeV
  • 2005
  • Ingår i: Physical Review Letters. - : American Physical Society. - 1079-7114. ; 95
  • Tidskriftsartikel (refereegranskat)abstract
    • Transverse single-spin asymmetries to probe the transverse-spin structure of the proton have been measured for neutral pions and nonidentified charged hadrons from polarized proton-proton collisions at midrapidity and root s = 200 GeV. The data cover a transverse momentum (pT) range 1.0-5.0 GeV/c for neutral pions and 0.5-5.0 GeV/c for charged hadrons, at a Feynman-x value of approximately zero. The asymmetries seen in this previously unexplored kinematic region are consistent with zero within errors of a few percent. In addition, the inclusive charged hadron cross section at midrapidity from 0.5 < P-T < 7.0 GeV/c is presented and compared to next-to-leading order perturbative QCD ( pQCD) calculations. Successful description of the unpolarized cross section above similar to 2 GeV/c suggests that pQCD is applicable in the interpretation of the asymmetry results in the relevant kinematic range.
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8.
  • Adler, SS, et al. (författare)
  • Midrapidity direct-photon production in p+p collisions at root s=200 GeV
  • 2005
  • Ingår i: Physical Review D (Particles and Fields). - : American Physical Society. - 0556-2821. ; 71:7
  • Tidskriftsartikel (refereegranskat)abstract
    • A measurement of direct photons in p+p collisions at root s=200 GeV is presented. A photon excess above background from pi(0)->gamma+gamma, eta ->gamma+gamma and other decays is observed in the transverse momentum range 5.5 < p(T)< 7 GeV/c. The result is compared to a next-to-leading-order perturbative QCD calculation. Within errors, good agreement is found between the QCD calculation and the measured result.
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9.
  • Adler, SS, et al. (författare)
  • Production of phi mesons at midrapidity in root S-NN=200 GeVAu+Au collisions at relativistic energies
  • 2005
  • Ingår i: Physical Review C (Nuclear Physics). - : American Physical Society. - 0556-2813. ; 72:1
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the results of phi meson production in the K+K- decay channel from Au+Au collisions at root s(NN) =200 GeV as measured at midrapidity by the PHENIX detector at Brookhaven National Laboratory's Relativistic Heavy Ion Collider. Precision resonance centroid and width values are extracted as a function of collision centrality. No significant variation from the Particle Data Group accepted values is observed, contrary to some model predictions. The phi transverse mass spectra are fitted with a linear exponential function for which the derived inverse slope parameter is seen to be constant as a function of centrality. However, when these data are fitted by a hydrodynamic model the result is that the centrality-dependent freeze-out temperature and the expansion velocity values are consistent with the values previously derived from fitting identified charged hadron data. As a function of transverse momentum the collisions scaled peripheral-to-central yield ratio R-CP for the phi is comparable to that of pions rather than that of protons. This result lends support to theoretical models that distinguish between baryons and mesons instead of particle mass for explaining the anomalous (anti) proton yield.
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10.
  • Adler, SS, et al. (författare)
  • Single electrons from heavy-flavor decays in p + p collisions at root s=200 GeV
  • 2006
  • Ingår i: Physical Review Letters. - : American Physical Society. - 1079-7114. ; 96:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The invariant differential cross section for inclusive electron production in p+p collisions at root s=200 GeV has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over the transverse momentum range 0.4 <= p(T) <= 5.0 GeV/c in the central rapidity region (vertical bar eta vertical bar <= 0.35). The contribution to the inclusive electron spectrum from semileptonic decays of hadrons carrying heavy flavor, i.e., charm quarks or, at high p(T), bottom quarks, is determined via three independent methods. The resulting electron spectrum from heavy-flavor decays is compared to recent leading and next-to-leading order perturbative QCD calculations. The total cross section of charm quark-antiquark pair production is determined to be sigma(c (c) over bar) = 0.92 +/- 0.15(stat) +/- 0.54(syst) mb.
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  • Resultat 1-10 av 11
  • [1]2Nästa

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