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1.
  • Adcox, K, et al. (författare)
  • PHENIX detector overview
  • 2003
  • Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 499:2-3, s. 469-479
  • Tidskriftsartikel (refereegranskat)abstract
    • The PHENIX detector is designed to perform a broad study of A-A, p-A, and p-p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed in other papers in this volume. The overall design parameters of the detector are presented. (C) 2002 Elsevier Science B.V. All rights reserved.
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2.
  • Adcox, K, et al. (författare)
  • Centrality dependence of the high (PT) charged hadron suppression in Au+Au collisions at root s(NN)=130 GeV
  • 2003
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 561:1-2, s. 82-92
  • Tidskriftsartikel (refereegranskat)abstract
    • PHENIX has measured the centrality dependence of charged hadron p(T) spectra from Au +An collisions at root(s)NN = 130 GeV The truncated mean p(T) decreases with centrality for p(T) > 2 GeV/c, indicating an apparent reduction of the contribution from hard scattering to high p(T) hadrdn production. For central collisions the yield at high p(T) is shown to be suppressed compared to binary nucleon-nucleon collision scaling of p + p, data. This suppression is monotonically increasing with centrality, but most of the change occurs below 30% centrality, i.e., for collisions with less than similar to140 participating nucleons. The observed p(T) and centrality dependence is consistent with the particle production predicted by models including hard scattering and subsequent energy loss of the scattered partons in the dense matter created in the collisions. (C) 2003 Published by Elsevier Science B.V.
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3.
  • Adcox, K, et al. (författare)
  • Event-by-event fluctuations in mean p(T) and mean E(T) in root s(NN)=130 GeVAu+Au collisions
  • 2002
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 66:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Distributions of event-by-event fluctuations of the mean transverse momentum and mean transverse energy near mid-rapidity have been measured in Au+Au collisions at roots(NN)=130 GeV at the Relativistic Heavy-Ion Collider. By comparing the distributions to what is expected for statistically independent particle emission, the magnitude of nonstatistical fluctuations in mean transverse momentum is determined to be consistent with zero. Also, no significant nonrandom fluctuations in mean transverse energy are observed. By constructing a fluctuation model with two event classes that preserve the mean and variance of the semi-inclusive p(T) or e(T) spectra, we exclude a region of fluctuations in roots(NN)=130 GeV Au+Au collisions.
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4.
  • Adcox, K, et al. (författare)
  • Flow Measurements via Two-Particle Azimuthal Correlations in Au+Au Collisions at sqrt[sNN]=130 GeV
  • 2002
  • Ingår i: Physical Review Letters. - 1079-7114. ; 89
  • Tidskriftsartikel (refereegranskat)abstract
    • Two-particle azimuthal correlation functions are presented for charged hadrons produced in Au+Au collisions at the Relativistic Heavy Ion Collider (sqrt[sNN]=130 GeV). The measurements permit determination of elliptic flow without event-by-event estimation of the reaction plane. The extracted elliptic flow values (v2) show significant sensitivity to both the collision centrality and the transverse momenta of emitted hadrons, suggesting rapid thermalization and relatively strong velocity fields. When scaled by the eccentricity of the collision zone ε, the scaled elliptic flow shows little or no dependence on centrality for charged hadrons with relatively low pT. A breakdown of this ε scaling is observed for charged hadrons with pT >1.0 GeV/c.
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5.
  • 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 BV. - 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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6.
  • Adcox, K, et al. (författare)
  • Measurement of Lambda and (Lambda)over-bar particles in Au plus Au collisions at root s(NN)=130 GeV
  • 2002
  • Ingår i: Physical Review Letters. - 1079-7114. ; 89:9
  • Tidskriftsartikel (refereegranskat)abstract
    • We present results on the measurement of Lambda and (&ULambda;) over bar production in Au+Au collisions at roots(NN)=130 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider. The transverse momentum spectra were measured for minimum bias and for the 5% most central events. The (&ULambda;) over bar/Lambda ratios are constant as a function of p(T) and the number of participants. The measured net Lambda density is significantly larger than predicted by models based on hadronic strings (e.g., HIJING) but in approximate agreement with models which include the gluon-junction mechanism.
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7.
  • Adcox, K, et al. (författare)
  • Measurement of single electrons and implications for charm production in Au+Au collisions at root(NN)-N-S=130 GeV
  • 2002
  • Ingår i: Physical Review Letters. - 1079-7114. ; 88:19
  • Tidskriftsartikel (refereegranskat)abstract
    • Transverse momentum spectra of electrons from Au+Au collisions at roots(NN) = 130 GeV have been measured at midrapidity by the PHENIX experiment at the Relativistic Heavy Ion Collider. The spectra show an excess above the background from photon conversions and light hadron decays. The electron signal is consistent with that expected from semileptonic decays of charm. The yield of the electron signal dN(e)/dy for p(T) > 0.8 GeV/c is 0.025 +/- 0.004(stat) +/- 0.010( syst) in central collisions, and the corresponding charm cross section is 380 +/- 60(stat) +/- 200(syst ) mub per binary nucleon-nucleon collision.
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8.
  • Adcox, K, et al. (författare)
  • Net charge fluctuations in Au+Au interactions root s(NN)=130 GeV
  • 2002
  • Ingår i: Physical Review Letters. - 1079-7114. ; 89
  • Tidskriftsartikel (refereegranskat)abstract
    • Data from Au+ Au interactions at s(NN)=130 GeV, obtained with the PHENIX detector at the Relativistic Heavy-Ion Collider, are used to investigate local net charge fluctuations among particles produced near midrapidity. According to recent suggestions, such fluctuations may carry information from the quark-gluon plasma. This analysis shows that the fluctuations are dominated by a stochastic distribution of particles, but are also sensitive to other effects, like global charge conservation and resonance decays.
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9.
  • Adcox, K, et al. (författare)
  • Suppression of hadrons with large transverse momentum in central Au+Au collisions at root s(NN)=130 GeV
  • 2002
  • Ingår i: Physical Review Letters. - 1079-7114. ; 88:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Transverse momentum spectra for charged hadrons and for neutral pions in the range 1 Gev/c < P-T < 5 GeV/c have been measured by the PHENIX experiment at RHIC in Au + Au collisions at rootS(NN) = 130 GeV. At high p(T) the spectra from peripheral nuclear collisions are consistent with scaling the spectra from p + p collisions by the average number of binary nucleon-nucleon collisions. The spectra from central collisions are significantly suppressed when compared to the binary-scaled p + p expectation, and also when compared to similarly binary-scaled peripheral collisions, indicating a novel nuclear-medium effect in central nuclear collisions at RHIC energies.
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10.
  • Adcox, K, et al. (författare)
  • Transverse-mass dependence of two-pion correlations in Au+Au collisions at root(NN)-N-S=130 GeV
  • 2002
  • Ingår i: Physical Review Letters. - 1079-7114. ; 88:19
  • Tidskriftsartikel (refereegranskat)abstract
    • Two-pion correlations in roots(NN) = 130 GeV Au+Au collisions at RHIC have been measured over a broad range of pair transverse momentum k(T) by the PHENIX experiment at RHIC. The k(T) dependent transverse radii are similar to results from heavy-ion collisions at roots(NN) = 4.1 , 4.9, and 17.3 GeV, whereas the longitudinal radius increases monotonically with beam energy. The ratio of the outwards to sidewards transverse radii (R-out/R-side) is consistent with unity and independent of k(T) .
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11.
  • Adler, SS, et al. (författare)
  • Bose-Einstein correlations of charged pion pairs in Au+Au collisions at root(NN)-N-s = 200 GeV
  • 2004
  • Ingår i: Physical Review Letters. - 1079-7114. ; 93:15
  • Tidskriftsartikel (refereegranskat)abstract
    • Bose-Einstein correlations of identically charged pion pairs were measured by the PHENIX experiment at midrapidity in Au+Au collisions at roots(NN)=200 GeV. The Bertsch-Pratt radius parameters were determined as a function of the transverse momentum of the pair and as a function of the centrality of the collision. Using the standard core-halo partial Coulomb fits, and a new parametrization which constrains the Coulomb fraction as determined from the unlike-sign pion correlation, the ratio R-out/R-side is within 0.8-1.1 for 0.25<<1.2 GeV/c. The centrality dependence of all radii is well described by a linear scaling in N-part(1/3), and R-out/R-side for similar to0.45 GeV/c is approximately constant at unity as a function of centrality.
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12.
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13.
  • 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. - 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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14.
  • 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. - 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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15.
  • Adler, SS, et al. (författare)
  • Double helicity asymmetry in inclusive midrapidity pi(0) production for polarized p+p collisions at root s=200 GeV
  • 2004
  • Ingår i: Physical Review Letters. - 1079-7114. ; 93:20: 202002
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a measurement of the double longitudinal spin asymmetry in inclusive pi(0) production in polarized proton-proton collisions at roots=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 0.27. The measurements are the first in a program to study the longitudinal spin structure of the proton, using strongly interacting probes, at collider energies. The asymmetry is presented for transverse momenta 1-5 GeV/c at midrapidity, where next-to-leading-order perturbative quantum chromodynamic (NLO pQCD) calculations well describe the unpolarized cross section. The observed asymmetry is small and is compared to a NLO pQCD calculation with a range of polarized gluon distributions.
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16.
  • Adler, SS, et al. (författare)
  • Elliptic flow of identified hadrons in Au+Au collisions at root s(NN)=200 GeV
  • 2003
  • Ingår i: Physical Review Letters. - 1079-7114. ; 91:18: 182301
  • Tidskriftsartikel (refereegranskat)abstract
    • The anisotropy parameter (v(2)), the second harmonic of the azimuthal particle distribution, has been measured with the PHENIX detector in Au+Au collisions at roots(NN)=200 GeV for identified and inclusive charged particle production at central rapidities (eta<0.35) with respect to the reaction plane defined at high rapidities (eta=3-4 ). We observe that the v(2) of mesons falls below that of (anti)baryons for p(T)>2 GeV/c, in marked contrast to the predictions of a hydrodynamical model. A quark-coalescence model is also investigated.
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17.
  • Adler, SS, et al. (författare)
  • Improved measurement of double helicity asymmetry in inclulsive midrapidity pi(0) production for polarized p+p collisions at root s=200 GeV
  • 2006
  • Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 73:9
  • Tidskriftsartikel (refereegranskat)abstract
    • We present an improved measurement of the double helicity asymmetry for pi(0) production in polarized proton-proton scattering at root s=200 GeV employing the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). The improvements to our previous measurement come from two main factors: Inclusion of a new data set from the 2004 RHIC run with higher beam polarizations than the earlier run and a recalibration of the beam polarization measurements for the earlier run, which resulted in reduced uncertainties and increased beam polarizations. The results are compared to a Next to Leading Order (NLO) perturbative Quantum Chromodynamics (pQCD) calculation with a range of polarized gluon distributions.
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18.
  • Adler, SS, et al. (författare)
  • J/psi production from proton-proton collisions at root s=200 GeV
  • 2004
  • Ingår i: Physical Review Letters. - 1079-7114. ; 92:5
  • Tidskriftsartikel (refereegranskat)abstract
    • J/psi production has been measured in proton-proton collisions at roots=200 GeV over a wide rapidity and transverse momentum range by the PHENIX experiment at the Relativistic Heavy Ion Collider. Distributions of the rapidity and transverse momentum, along with measurements of the mean transverse momentum and total production cross section are presented and compared to available theoretical calculations. The total J/psi cross section is 4.0+/-0.6(stat)+/-0.6(syst)+/-0.4(abs) mub. The mean transverse momentum is 1.80+/-0.23(stat)+/-0.16(syst) GeV/c.
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19.
  • Adler, SS, et al. (författare)
  • J/psi production in Au-Au collisions at root s(NN)=200 GeV
  • 2004
  • Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 69:1
  • Tidskriftsartikel (refereegranskat)abstract
    • First results on charm quarkonia production in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The yield of J/psi's measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au-Au reactions at roots(NN) = 200 GeV is analyzed as a function of collision centrality. For this analysis we have studied 49.3x10(6) minimum bias Au-Au reactions. We present the J/psi invariant yield dN/dy for peripheral and midcentral reactions. For the most central collisions where we observe no signal above background, we quote 90% confidence level upper limits. We compare these results with our J/psi measurement from proton-proton reactions at the same energy. We find that our measurements are not consistent with models that predict strong enhancement relative to binary collision scaling.
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20.
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21.
  • 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). - 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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22.
  • 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. - 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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23.
  • 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). - 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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24.
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25.
  • 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). - 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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26.
  • Adler, SS, et al. (författare)
  • Scaling properties of proton and antiproton production in root s(NN)=200 GeV Au+Au collisions
  • 2003
  • Ingår i: Physical Review Letters. - 1079-7114. ; 91:17: 172301
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the yield of protons and antiprotons, as a function of centrality and transverse momentum, in Au+Au collisions at rootS(NN)=200 GeV measured at midrapidity by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider. In central collisions at intermediate transverse momenta (1.5
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27.
  • 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. - 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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28.
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