[en] Recent PHENIX Au+Au→e^-+X data [Phys. Rev. Lett. 88 (2002) 192303] from open charm decay are shown to be consistent with two extreme opposite dynamical scenarios of ultra-relativistic nuclear reactions. Perturbative QCD without final state interactions was previously shown to be consistent with the data. However, we show that the data are also consistent with zero mean free path hydrodynamics characterized by a common transverse flow velocity field. The surprising coincidence of both D and B hydrodynamic flow spectra with pQCD up to p_T∼3 and 5 GeV, respectively, suggests that heavy quarks may be produced essentially at rest in the rapidly expanding gluon plasma. Possible implications and further tests of collective heavy quark dynamics are discussed

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[en] Measurements in Au+Au collisions at √(s_NN)=200 GeV of jet correlations for a trigger hadron at intermediate transverse momentum (p_T,trig) with associated mesons or baryons at lower p_T,assoc indicate strong modification of the away-side jet. The ratio of jet-associated baryons to mesons increases with centrality and p_T,assoc. For the most central collisions, the ratio is similar to that for inclusive measurements. This trend is incompatible with in-vacuum fragmentation but could be due to jetlike contributions from correlated soft partons, which recombine upon hadronization

[en] We present inclusive charged hadron elliptic flow (v₂) measured over the pseudorapidity range |η|<0.35 in Au+Au collisions at √(s_NN)=200 GeV. Results for v₂ are presented over a broad range of transverse momentum (p_T=0.2-8.0 GeV/c) and centrality (0-60%). To study nonflow effects that are correlations other than collective flow, as well as the fluctuations of v₂, we compare two different analysis methods: (1) the event-plane method from two independent subdetectors at forward (|η|=3.1-3.9) and beam (|η|>6.5) pseudorapidities and (2) the two-particle cumulant method extracted using correlations between particles detected at midrapidity. The two event-plane results are consistent within systematic uncertainties over the measured p_T and in centrality 0-40%. There is at most a 20% difference in the v₂ between the two event-plane methods in peripheral (40-60%) collisions. The comparisons between the two-particle cumulant results and the standard event-plane measurements are discussed.

[en] We report measurements from experiment E864 at the BNL-AGS of the yields of particle unstable light nuclei in central collisions of ¹⁹⁷Au with beam momentum of 11.5A GeV/c on ¹⁹⁷Pt. Yields are reported as a function of rapidity for the nuclei ⁴H, ⁴Li, ⁵He, and ⁵Li in the rapidity range from y_c.m. to y_c.m.+0.8 and in the transverse momentum range of approximately 0.1≤p_T/A≤0.4 GeV/c. The yields are compared to previously reported yields and trends for the production of stable light nuclei. The nonobservation of two excited states ⁵He_16.75MeV* and ⁵Li_16.66MeV* is used to set an upper limit on the yields of these states

[en] Bose-Einstein correlations of charged kaons are used to probe Au+Au collisions at √(s_NN)=200 GeV and are compared to charged pion probes, which have a larger hadronic scattering cross section. Three-dimensional Gaussian source radii are extracted, along with a one-dimensional kaon emission source function. The centrality dependences of the three Gaussian radii are well described by a single linear function of N_part^1/3 with a zero intercept. Imaging analysis shows a deviation from a Gaussian tail at r > or approx. 10 fm, although the bulk emission at lower radius is well described by a Gaussian. The presence of a non-Gaussian tail in the kaon source reaffirms that the particle emission region in a heavy-ion collision is extended, and that similar measurements with pions are not solely due to the decay of long-lived resonances.

[en] We present measurements from BNL AGS Experiment 864 of the _Λ³H yield and of an upper limit on the _Λ⁴H yield in central 11.5A GeV/c Au+Pt collisions. The measurements span a rapidity range from center of mass, y_c.m., to y_c.m.+1 and a transverse momentum range of 0< p_t≤1.5 GeV/c. We compare these results with E864 measurements of stable light nuclei and particle unstable nuclei yields of the same baryon number. The implications of these results for the coalescence of strange clusters are discussed

[en] Differential elliptic flow (v₂) for φ mesons and (anti)deuterons (d)d is measured for Au+Au collisions at √(s_NN)=200 GeV. The v₂ for φ mesons follows the trend of lighter π^± and K^± mesons, suggesting that ordinary hadrons interacting with standard hadronic cross sections are not the primary driver for elliptic flow development. The v₂ values for (d)d suggest that elliptic flow is additive for composite particles. This further validation of the universal scaling of v₂ per constituent quark for baryons and mesons suggests that partonic collectivity dominates the transverse expansion dynamics

[en] Measurements of the azimuthal anisotropy of high-p_T neutral pion (π⁰) production in Au+Au collisions at √(s_NN)=200 GeV by the PHENIX experiment are presented. The data included in this article were collected during the 2004 Relativistic Heavy Ion Collider running period and represent approximately an order of magnitude increase in the number of analyzed events relative to previously published results. Azimuthal angle distributions of π⁰ mesons detected in the PHENIX electromagnetic calorimeters are measured relative to the reaction plane determined event-by-event using the forward and backward beam-beam counters. Amplitudes of the second Fourier component (v₂) of the angular distributions are presented as a function of π⁰ transverse momentum (p_T) for different bins in collision centrality. Measured reaction plane dependent π⁰ yields are used to determine the azimuthal dependence of the π⁰ suppression as a function of p_T, R_AA(Δφ,p_T). A jet-quenching motivated geometric analysis is presented that attempts to simultaneously describe the centrality dependence and reaction plane angle dependence of the π⁰ suppression in terms of the path lengths of hypothetical parent partons in the medium. This set of results allows for a detailed examination of the influence of geometry in the collision region and of the interplay between collective flow and jet-quenching effects along the azimuthal axis.

[en] A three-dimensional correlation function obtained from midrapidity, low p_T, pion pairs in central Au+Au collisions at √(s_NN)=200 GeV is studied. The extracted model-independent source function indicates a long range tail in the directions of the pion pair transverse momentum (out) and the beam (long). A proper breakup time τ₀∼9 fm/c and a mean proper emission duration Δτ∼2 fm/c, leading to sizable emission time differences (<|Δt_LCM|>≅12 fm/c), are required to allow models to be successfully matched to these tails. The model comparisons also suggest an outside-in 'burning' of the emission source reminiscent of many hydrodynamical models