Neutral pion transverse momentum (pT) spectra at midrapidity (|y|≲0.35) were measured in Cu+Cu collisions at sNN=22.4, 62.4, and 200 GeV. Relative to π0 yields in p+p collisions scaled by the number of inelastic nucl...
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Neutral pion transverse momentum (pT) spectra at midrapidity (|y|≲0.35) were measured in Cu+Cu collisions at sNN=22.4, 62.4, and 200 GeV. Relative to π0 yields in p+p collisions scaled by the number of inelastic nucleon-nucleon collisions (Ncoll) the π0 yields for pT≳2 GeV/c in central Cu+Cu collisions are suppressed at 62.4 and 200 GeV whereas an enhancement is observed at 22.4 GeV. A comparison with a jet-quenching model suggests that final state parton energy loss dominates in central Cu+Cu collisions at 62.4 and 200 GeV, while the enhancement at 22.4 GeV is consistent with nuclear modifications in the initial state alone.
A three-dimensional correlation function obtained from midrapidity, low pT, pion pairs in central Au+Au collisions at sNN=200 GeV is studied. The extracted model-independent source function indicates a long range tai...
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A three-dimensional correlation function obtained from midrapidity, low pT, pion pairs in central Au+Au collisions at sNN=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 (⟨|ΔtLCM|⟩≈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.
Measurements in Au+Au collisions at sNN=200 GeV of jet correlations for a trigger hadron at intermediate transverse momentum (pT,trig) with associated mesons or baryons at lower pT,assoc indicate strong modification ...
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Measurements in Au+Au collisions at sNN=200 GeV of jet correlations for a trigger hadron at intermediate transverse momentum (pT,trig) with associated mesons or baryons at lower pT,assoc indicate strong modification of the away-side jet. The ratio of jet-associated baryons to mesons increases with centrality and pT,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.
For Au+Au collisions at 200 GeV, we measure neutral pion production with good statistics for transverse momentum, pT, up to 20 GeV/c. A fivefold suppression is found, which is essentially constant for 5<pT<20 ...
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For Au+Au collisions at 200 GeV, we measure neutral pion production with good statistics for transverse momentum, pT, up to 20 GeV/c. A fivefold suppression is found, which is essentially constant for 5
I. Introduction (Z. Lin, G. Y. Fu, J. Q. Dong) II. Role of theory and simulation in fusion sciences 1. The Impact of theory and simulation on tokomak experiments (H. R. Wilson, T.S. Hahm and F. Zonca) 2. Tokomak Trans...
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I. Introduction (Z. Lin, G. Y. Fu, J. Q. Dong) II. Role of theory and simulation in fusion sciences 1. The Impact of theory and simulation on tokomak experiments (H. R. Wilson, T.S. Hahm and F. Zonca) 2. Tokomak Transport physics for the Era of ITER: Issues for Simulations (P.H. Diamond and T.S. Hahm) III. Status of fusion simulation and modeling 1. Nonlinear Governing Equations for Plasma Simulations (T. S. Hahm) 2. Equilibrium and stability (L.L. Lao, J. Manickam) 3. Transport modeling (R.E. Waltz) 4. Nonlinear MHD (G.Y. Fu) 5. Turbulence (Z. Lin and R.E. Waltz) 6. RF heating and current drive (D.A. Batchelor) 7. Edge physics Simulations (X.Q. Xu and C.S. Chang) 8. Energetic particle physics (F. Zonca, G.Y. Fu and S.J. Wang) 9. Time-dependent Integrated Modeling (R.V. Budny) 10. Validation and verification (J. Manickam) IV. Major initiatives on fusion simulation 1. US Scientific Discovery through Advanced Computing (SciDAC) program & Fusion Energy science (W. Tang) 2. EU Integrated Tokamak Modelling (ITM) Task Force (A. Becoulet) 3. Fusion Simulations Activities in Japan (A. Fukuyama, N. Nakajima, Y. Kishimoto, T. Ozeki, and M. Yagi) V. Cross-disciplinary research in fusion simulation 1. applied mathematics: Models, Discretizations, and Solvers (D.E. Keyes) 2. Computational science (K. Li) 3. Scientific Data and Workflow Management (S. Klasky, M. Beck, B. Ludaescher, N. Podhorszki, M.A. Vouk) 4. Collaborative tools (J. Manickam)
We present transverse momentum (pT) spectra of charged hadrons measured in deuteron-gold and nucleon-gold collisions at sNN=200 GeV for four centrality classes. Nucleon-gold collisions were selected by tagging events ...
We present transverse momentum (pT) spectra of charged hadrons measured in deuteron-gold and nucleon-gold collisions at sNN=200 GeV for four centrality classes. Nucleon-gold collisions were selected by tagging events in which a spectator nucleon was observed in one of two forward rapidity detectors. The spectra and yields were investigated as a function of the number of binary nucleon-nucleon collisions, ν, suffered by deuteron nucleons. A comparison of charged particle yields to those in p+p collisions show that yield per nucleon-nucleon collision saturates with ν for high momentum particles. We also present the charged hadron to neutral pion ratios as a function of pT.
A comprehensive survey of event-by-event fluctuations of charged hadron multiplicity in relativistic heavy ions is presented. The survey covers Au+Au collisions at sNN=62.4 and 200 GeV, and Cu+Cu collisions at sNN=22....
A comprehensive survey of event-by-event fluctuations of charged hadron multiplicity in relativistic heavy ions is presented. The survey covers Au+Au collisions at sNN=62.4 and 200 GeV, and Cu+Cu collisions at sNN=22.5,62.4, and 200 GeV. Fluctuations are measured as a function of collision centrality, transverse momentum range, and charge sign. After correcting for nondynamical fluctuations due to fluctuations in the collision geometry within a centrality bin, the remaining dynamical fluctuations expressed as the variance normalized by the mean tend to decrease with increasing centrality. The dynamical fluctuations are consistent with or below the expectation from a superposition of participant nucleon-nucleon collisions based upon p+p data, indicating that this dataset does not exhibit evidence of critical behavior in terms of the compressibility of the system. A comparison of the data with a model where hadrons are independently emitted from a number of hadron clusters suggests that the mean number of hadrons per cluster is small in heavy ion collisions.
We present a new analysis of J/ψ production yields in deuteron-gold collisions at sNN=200 GeV using data taken from the PHENIX experiment in 2003 and previously published in S. S. Adler et al. [Phys. Rev. Lett 96, 01...
We present a new analysis of J/ψ production yields in deuteron-gold collisions at sNN=200 GeV using data taken from the PHENIX experiment in 2003 and previously published in S. S. Adler et al. [Phys. Rev. Lett 96, 012304 (2006)]. The high statistics proton-proton J/ψ data taken in 2005 are used to improve the baseline measurement and thus construct updated cold nuclear matter modification factors (RdAu). A suppression of J/ψ in cold nuclear matter is observed as one goes forward in rapidity (in the deuteron-going direction), corresponding to a region more sensitive to initial-state low-x gluons in the gold nucleus. The measured nuclear modification factors are compared to theoretical calculations of nuclear shadowing to which a J/ψ (or precursor) breakup cross section is added. Breakup cross sections of σbreakup=2.8−1.4+1.7 (2.2−1.5+1.6) mb are obtained by fitting these calculations to the data using two different models of nuclear shadowing. These breakup cross-section values are consistent within large uncertainties with the 4.2±0.5 mb determined at lower collision energies. Projecting this range of cold nuclear matter effects to copper-copper and gold-gold collisions reveals that the current constraints are not sufficient to firmly quantify the additional hot nuclear matter effect.
Azimuthal angle (Δϕ) correlations are presented for a broad range of transverse momentum (0.4<pT<10 GeV/c) and centrality (0–92%) selections for charged hadrons from dijets in Au+Au collisions at sNN=200 GeV. ...
Azimuthal angle (Δϕ) correlations are presented for a broad range of transverse momentum (0.4
The PHENIX experiment has measured the suppression of semi-inclusive single high-transverse-momentum π0's in Au+Au collisions at sNN=200 GeV. The present understanding of this suppression is in terms of energy lo...
The PHENIX experiment has measured the suppression of semi-inclusive single high-transverse-momentum π0's in Au+Au collisions at sNN=200 GeV. The present understanding of this suppression is in terms of energy loss of the parent (fragmenting) parton in a dense color-charge medium. We have performed a quantitative comparison between various parton energy-loss models and our experimental data. The statistical point-to-point uncorrelated as well as correlated systematic uncertainties are taken into account in the comparison. We detail this methodology and the resulting constraint on the model parameters, such as the initial color-charge density dNg/dy, the medium transport coefficient 〈q^〉, or the initial energy-loss parameter ε0. We find that high-transverse-momentum π0 suppression in Au+Au collisions has sufficient precision to constrain these model-dependent parameters at the ±20–25% (one standard deviation) level. These constraints include only the experimental uncertainties, and further studies are needed to compute the corresponding theoretical uncertainties.
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