Measurement of density correlations in pseudorapidity via charged particle multiplicity fluctuations in Au+Au collisions at sNN\sqrt{s_{NN}}=200 GeV

331 authors, 32 pages text, RevTeX4, 7 figures, 27 tables. Submitted to Physical Review C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htmlLongitudinal density correlations of produced matter in Au+Au collisions at sqrt(s_NN)=200 GeV have been measured from the inclusive charged particle distributions as a function of pseudorapidity window sizes. The extracted \alpha \xi parameter, related to the susceptibility of the density fluctuations in the long wavelength limit, exhibits a non-monotonic behavior as a function of the number of participant nucleons, N_part. A local maximum is seen at N_part ~ 90, with corresponding energy density based on the Bjorken picture of \epsilon_Bj \tau ~ 2.4 GeV/(fm^2 c) with a transverse area size of 60 fm^2. This behavior may suggest a critical phase boundary based on the Ginzburg-Landau framework

Low mass dilepton production at RHIC energies

EIRecent results on low mass dilepton measurements from the PHENIX experiment are reported. Invariant mass spectra of $\phi-> e+e-$ are measured for the first time in Au-Au collisions at $\sqrt{^{S}NN} = 200 GeV$ in Run2. In d-Au collisions, the yields and MT slopes of both $\phi ->e+e-$ and $\phi-> K+K-$ are measured. Both results are consistent with each other within errors. In the future, a Hadron Blind Detector will be installed in PHENIX which will enhance our capabilities of rejecting external photon conversions and Dalitz pairs, that will result in a significant reduction of the large combinatorial background

Heavy flavor production in PHENIX

O. Drapier on behalf of the PHENIX Collaboration, EIThe PHENIX experiment at RHIC measured single electron spectra in p + p, d + Au and Au + Au collisions at $\sqrt{s_{NN}} = 200$ GeV, and in Au + Au collisions at $\sqrt{s_{NN}} = 62.4$ GeV. In these spectra, electrons from semi-leptonic decays of charmed particles are the dominant contribution after subtraction of all 'photonic' sources (photon conversions, Dalitz decays, decays of light vector mesons). The p + p open charm production cross-section is found to be in good agreement with pQCD NLO calculations. The shape of the distributions obtained for p + p interactions is compared with those observed for nucleus-nucleus collisions. From p + p to d + Au and Au + Au interactions, open charm production is found to scale with the number of binary collisions $N_{\rm coll}$ . Au + Au data at $\sqrt{s_{NN}} = 62.4$ GeV is compatible with the ISR p + p results scaled by $N_{\rm coll}$ . The elliptic flow parameter v2 of heavy flavor electrons has also been measured, and is found to be non-zero in the intermediate pT range

Medium effects on high ¶T\P_{T} particle production measured with the PHENIX experiment

EITransverse momentum $\P_{T}$ spectra measured by the PHENIX experiment at RHIC in Au + Au, d + Au and pp collisions at $\sqrt {^S{NN}} = 200 GeV$ and in Au + Au collisions at $\sqrt {^S{NN}} = 62.4 GeV$ are presented. A suppression of the yield of high $\P_{T}$ hadrons in central Au + Au collisions by a factor 4-5 at $\P_{T}>5$ is found relative to the pp reference scaled by the nuclear overlap function (\T_{AB}) . In contrast, direct photons are not suppressed in central Au + Au collisions and no suppression of high $\P_{T}$ particles can be seen in d + Au collisions. This leads to the conclusion that the dense medium formed in central Au + Au collisions is responsible for the suppression

Can ϕ\phi mesons give an answer to the baryon puzzle at RHIC?

EIInternational audienceThe PHENIX experiment at RHIC has observed a large enhancement of baryon and anti-baryon production at ~ 2-5 GeV/c, compared to expectations from jet fragmentation. While a number of theoretical interpretations of the data are available, there is not yet a definitive answer to the “baryon puzzle”. We investigate the centrality dependence of -meson production at mid-rapidity in Au + Au collisions with $sqrt {^{s}NN}=200 GeV$. Comparison with the proton and anti-proton spectra reveal similar shapes, as expected for soft production described by hydrodynamics. However, the absolute yields show a different centrality dependence. The nuclear modification factors for $\phi$ are similar to those of pions, rather than (anti)protons that have similar mass. At intermediate , baryon/meson effects seem to be more important than the mass effects, in support of recombination models