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AbstractAbstract
[en] The first detailed measurements of the centrality dependence of strangeness production in p-A collisions are presented. Λ and KS dn/dy distributions from 17.5GeV/c p-Au collisions are shown as a function of ''grey'' track multiplicity and the estimated number of collisions, ν , made by the proton. The ν dependence of the Λ yield deviates from a scaling of p-p data by the number of participants, increasing faster than this scaling for ν≤5 and saturating for larger ν . A slower growth in KS multiplicity with ν is observed, consistent with a weaker ν dependence of Kbar K production than YK production
Primary Subject
Source
Othernumber: PRLTAO000085000023004868000001; 042049PRL; The American Physical Society
Record Type
Journal Article
Journal
Physical Review Letters; ISSN 0031-9007; ; v. 85(23); p. 4868-4871
Country of publication
BARYON REACTIONS, BARYONS, BOSONS, CHARGED-PARTICLE REACTIONS, ELEMENTARY PARTICLES, ELEMENTS, FERMIONS, HADRON REACTIONS, HADRONS, HYPERONS, KAONS, KAONS NEUTRAL, LAMBDA BARYONS, MESONS, METALS, NUCLEAR REACTIONS, NUCLEON REACTIONS, PARTICLE PRODUCTION, PARTICLE PROPERTIES, PSEUDOSCALAR MESONS, STRANGE MESONS, STRANGE PARTICLES, TRANSITION ELEMENTS
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AbstractAbstract
[en] We find that the current radiative energy loss kernels obtained from the opacity expansion dramatically violate the collinear approximation used in their derivation. By keeping only the lowest order in collinearity terms, models based on the opacity expansion have ∼50% systematic uncertainty in the calculation of π0 RAA in the most central RHIC collisions, resulting in a systematic uncertainty of ∼200% in the extracted medium density. Surprisingly, the inclusion of a thermal gluon mass of the order of the Debye screening scale affects RAA only at about the 5% level due to nonintuitive coherence effects. For some observables such as RAA, the effect of these uncertainties decreases with increasing jet energy; for others, such as the average number of radiated gluons, the effect is energy independent. We note that it is likely that the differences reported in the extracted values of medium parameters such as q by various jet energy loss models will fall within this collinear approximation systematic uncertainty; it is imperative for the quantitative extraction of medium parameters or the possible falsification of the hypothesis of weak coupling between the hard probes and the soft modes of the quark-gluon plasma medium that future radiative energy loss research push beyond the lowest-order collinear approximation.
Primary Subject
Source
(c) 2010 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
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Journal Article
Journal
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
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Chemakin, I.; Cianciolo, V.; Cole, B. A.; Fernow, R. C.; Frawley, A. D.; Gilkes, M.; Gushue, S.; Hartouni, E. P.; Hiejima, H.; Justice, M.; Kang, J. H.; Kirk, H. G.; Link, J. M.; Maeda, N.; McGrath, R. L.; Mioduszewski, S.; Monroe, J.; Morrison, D.; Moulson, M.; Namboodiri, M. N.
arXiv e-print [ PDF ]2008
arXiv e-print [ PDF ]2008
AbstractAbstract
No abstract available
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Secondary Subject
Source
(c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
External URLExternal URL
Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L.; Aidala, C.; Batsouli, S.; Bjorndal, M. T.; Chi, C. Y.; Chiu, M.; Cole, B. A.; D'Enterria, D.; Frantz, J. E.; Jia, J.; Jin, J.; Winter, D.; Zajc, W. A.; Zhang, C.
PHENIX Collaboration
arXiv e-print [ PDF ]2009
PHENIX Collaboration
arXiv e-print [ PDF ]2009
AbstractAbstract
[en] Measurements of the azimuthal anisotropy of high-pT neutral pion (π0) production in Au+Au collisions at √(sNN)=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 (pT) 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 pT, RAA(Δφ,pT). 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.
Primary Subject
Source
(c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
External URLExternal URL
Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L.; Aidala, C.; Batsouli, S.; Bjorndal, M. T.; Chi, C. Y.; Chiu, M.; Cole, B. A.; D'Enterria, D.; Frantz, J. E.; Jia, J.; Jin, J.; Winter, D.; Zajc, W. A.; Zhang, C.
PHENIX Collaboration
arXiv e-print [ PDF ]2008
PHENIX Collaboration
arXiv e-print [ PDF ]2008
AbstractAbstract
[en] 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
Primary Subject
Source
(c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
External URLExternal URL
Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L.; Aidala, C.; Batsouli, S.; Bjorndal, M. T.; Chi, C. Y.; Chiu, M.; Cole, B. A.; D'Enterria, D.; Frantz, J. E.; Jia, J.; Jin, J.; Winter, D.; Zajc, W. A.; Zhang, C.
PHENIX Collaboration
arXiv e-print [ PDF ]2009
PHENIX Collaboration
arXiv e-print [ PDF ]2009
AbstractAbstract
[en] We present inclusive charged hadron elliptic flow (v2) measured over the pseudorapidity range |η|<0.35 in Au+Au collisions at √(sNN)=200 GeV. Results for v2 are presented over a broad range of transverse momentum (pT=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 pT 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.
Primary Subject
Source
(c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
External URLExternal URL
Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L.; Aidala, C.; Batsouli, S.; Bjorndal, M. T.; Chi, C. Y.; Chiu, M.; Cole, B. A.; D'Enterria, D.; Frantz, J. E.; Jia, J.; Jin, J.; Winter, D.; Zajc, W. A.; Zhang, C.
PHENIX Collaboration
arXiv e-print [ PDF ]2007
PHENIX Collaboration
arXiv e-print [ PDF ]2007
AbstractAbstract
[en] Differential elliptic flow (v2) for φ mesons and (anti)deuterons (d)d is measured for Au+Au collisions at √(sNN)=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
Primary Subject
Source
(c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
External URLExternal URL
Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L.; Aidala, C.; Batsouli, S.; Bjorndal, M. T.; Chi, C. Y.; Chiu, M.; Cole, B. A.; D'Enterria, D.; Frantz, J. E.; Jia, J.; Jin, J.; Winter, D.; Zajc, W. A.; Zhang, C.
PHENIX Collaboration
arXiv e-print [ PDF ]2008
PHENIX Collaboration
arXiv e-print [ PDF ]2008
AbstractAbstract
[en] 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
Primary Subject
Source
(c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Country of publication
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
External URLExternal URL
Adare, A.; Bickley, A. A.; Ellinghaus, F.; Glenn, A.; Kinney, E.; Nagle, J. L.; Seele, J.; Wysocki, M.; Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L.; Aidala, C.; Chi, C. Y.; Cole, B. A.; D'Enterria, D.; Jia, J.
PHENIX Collaboration
arXiv e-print [ PDF ]2007
PHENIX Collaboration
arXiv e-print [ PDF ]2007
AbstractAbstract
[en] The PHENIX experiment presents results from the Relativistic Heavy Ion Collider 2005 run with polarized proton collisions at √(s)=200 GeV, for inclusive π0 production at midrapidity. Unpolarized cross section results are given for transverse momenta pT=0.5 to 20 GeV/c, extending the range of published data to both lower and higher pT. The cross section is described well for pT<1 GeV/c by an exponential in pT, and, for pT>2 GeV/c, by perturbative QCD. Double helicity asymmetries ALL are presented based on a factor of 5 improvement in uncertainties as compared to previously published results, due to both an improved beam polarization of 50%, and to higher integrated luminosity. These measurements are sensitive to the gluon polarization in the proton. Using one representative model of gluon polarization it is demonstrated that the gluon spin contribution to the proton spin is significantly constrained
Primary Subject
Secondary Subject
Source
(c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Country of publication
ACCELERATORS, ANGULAR MOMENTUM, BARYONS, BOSONS, ELEMENTARY PARTICLES, ENERGY RANGE, FERMIONS, FIELD THEORIES, HADRONS, HEAVY ION ACCELERATORS, LINEAR MOMENTUM, MEASURING INSTRUMENTS, MESONS, NUCLEONS, PARTICLE PROPERTIES, PIONS, PSEUDOSCALAR MESONS, QUANTUM FIELD THEORY, SPECTROMETERS, STORAGE RINGS
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
External URLExternal URL
Adare, A.; Bickley, A. A.; Ellinghaus, F.; Kelly, S.; Kinney, E.; Nagle, J. L.; Seele, J.; Wysocki, M.; Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L.; Aidala, C.; Bjorndal, M. T.; Chi, C. Y.; Cole, B. A.; D'Enterria, D.
PHENIX Collaboration
arXiv e-print [ PDF ]2010
PHENIX Collaboration
arXiv e-print [ PDF ]2010
AbstractAbstract
[en] The production of e+e- pairs for me+e-<0.3 GeV/c2 and 1< pT<5 GeV/c is measured in p+p and Au+Au collisions at √(sNN)=200 GeV. An enhanced yield above hadronic sources is observed. Treating the excess as photon internal conversions, the invariant yield of direct photons is deduced. In central Au+Au collisions, the excess of the direct photon yield over p+p is exponential in transverse momentum, with an inverse slope T=221±19stat±19syst MeV. Hydrodynamical models with initial temperatures ranging from Tinit∼300-600 MeV at times of ∼0.6-0.15 fm/c after the collision are in qualitative agreement with the data. Lattice QCD predicts a phase transition to quark gluon plasma at ∼170 MeV.
Primary Subject
Source
(c) 2010 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Country of publication
ANTILEPTONS, ANTIMATTER, ANTIPARTICLES, ATOM COLLISIONS, BOSONS, COLLISIONS, CONVERSION, DECAY, ELEMENTARY PARTICLES, ELEMENTS, ENERGY RANGE, FERMIONS, FIELD THEORIES, INTERACTIONS, LEPTONS, LINEAR MOMENTUM, MASSLESS PARTICLES, MATTER, METALS, NUCLEAR DECAY, PARTICLE INTERACTIONS, PARTICLE PRODUCTION, QUANTUM FIELD THEORY, TRANSITION ELEMENTS
Reference NumberReference Number
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