| 1. |
- Adare, A., et al.
(författare)
-
Direct photon production in d+Au collisions at root s(NN)=200 GeV
- 2013
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 87:5
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Tidskriftsartikel (refereegranskat)abstract
- Direct photons have been measured in root s(NN) = 200 GeV d + Au collisions at midrapidity. A wide p(T) range is covered by measurements of nearly real virtual photons (1 < p(T) < 6 GeV/c) and real photons (5 < p(T) < 16 GeV/c). The invariant yield of the direct photons in d + Au collisions over the scaled p + p cross section is consistent with unity. Theoretical calculations assuming standard cold-nuclear-matter effects describe the data well for the entire p(T) range. This indicates that the large enhancement of direct photons observed in Au + Au collisions for 1.0 < p(T) < 2.5 GeV/c is attributable to a source other than the initial-state nuclear effects.
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| 2. |
- Adare, A., et al.
(författare)
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Production of omega mesons in p plus p, d plus Au, Cu plus Cu, and Au plus Au collisions at root s(NN)=200 GeV
- 2011
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 84:4
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Tidskriftsartikel (refereegranskat)abstract
- The PHENIX experiment at the Relativistic Heavy Ion Collider has measured omega meson production via leptonic and hadronic decay channels in p + p, d + Au, Cu+ Cu, and Au + Au collisions at root s(NN) = 200 GeV. The invariant transverse momentum spectra measured in different decay modes give consistent results. Measurements in the hadronic decay channel in Cu Cu and Au + Au collisions show that. production has a suppression pattern at high transverse momentum, similar to that of pi(0) and eta in central collisions, but no suppression is observed in peripheral collisions. The nuclear modification factors, R-AA, are consistent in Cu + Cu and Au + Au collisions at similar numbers of participant nucleons.
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| 3. |
- Adare, A., et al.
(författare)
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Nuclear modification factors of phi mesons in d plus Au, Cu plus Cu, and Au plus Au collisions at root s(NN)=200 GeV
- 2011
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 83:2
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Tidskriftsartikel (refereegranskat)abstract
- The PHENIX experiment at the Relativistic Heavy Ion Collider has performed systematic measurements of phi meson production in the K+K- decay channel at midrapidity in p + p, d + Au, Cu + Cu, and Au + Au collisions at root s(NN) = 200 GeV. Results are presented on the phi invariant yield and the nuclear modification factor R-AA for Au + Au and Cu + Cu, and R-dA for d + Au collisions, studied as a function of transverse momentum (1 < p(T) < 7 GeV/c) and centrality. In central and midcentral Au + Au collisions, the R-AA of phi exhibits a suppression relative to expectations from binary scaled p + p results. The amount of suppression is smaller than that of the pi(0) and the. in the intermediate p(T) range (2-5 GeV/c), whereas, at higher p(T), the phi, pi(0), and. show similar suppression. The baryon (proton and antiproton) excess observed in central Au + Au collisions at intermediate p(T) is not observed for the phi meson despite the similar masses of the proton and the phi. This suggests that the excess is linked to the number of valence quarks in the hadron rather than its mass. The difference gradually disappears with decreasing centrality, and, for peripheral collisions, the R-AA values for both particle species are consistent with binary scaling. Cu + Cu collisions show the same yield and suppression as Au + Au collisions for the same number of N-part. The R-dA of phi shows no evidence for cold nuclear effects within uncertainties.
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| 4. |
- Adare, A., et al.
(författare)
-
Photon-hadron jet correlations in p plus p and Au plus Au collisions at s(NN)=200 GeV
- 2009
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:2
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Tidskriftsartikel (refereegranskat)abstract
- We report the observation at the Relativistic Heavy Ion Collider of suppression of back-to-back correlations in the direct photon+jet channel in Au+Au relative to p+p collisions. Two-particle correlations of direct photon triggers with associated hadrons are obtained by statistical subtraction of the decay photon-hadron (gamma-h) background. The initial momentum of the away-side parton is tightly constrained, because the parton-photon pair exactly balance in momentum at leading order in perturbative quantum chromodynamics, making such correlations a powerful probe of the in-medium parton energy loss. The away-side nuclear suppression factor, I-AA, in central Au+Au collisions, is 0.32 +/- 0.12(stat)+/- 0.09(syst) for hadrons of 3 < p(T)(h)< 5 in coincidence with photons of 5 < p(T)(gamma)< 15 GeV/c. The suppression is comparable to that observed for high-p(T) single hadrons and dihadrons. The direct photon associated yields in p+p collisions scale approximately with the momentum balance, z(T)equivalent to p(T)(h)/p(T)(gamma), as expected for a measurement of the away-side parton fragmentation function. We compare to Au+Au collisions for which the momentum balance dependence of the nuclear modification should be sensitive to the path-length dependence of parton energy loss.
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| 5. |
- Adare, A., et al.
(författare)
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Charged hadron multiplicity fluctuations in Au plus Au and Cu plus Cu collisions from s(NN)=22.5 to 200 GeV
- 2008
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 78:4
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Tidskriftsartikel (refereegranskat)abstract
- 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 s(NN)=62.4 and 200 GeV, and Cu+Cu collisions at s(NN)=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.
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| 6. |
- Adare, A., et al.
(författare)
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Cold nuclear matter effects on J/psi production as constrained by deuteron-gold measurements at root S-NN=200 GeV
- 2008
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 77:2, s. 15-024912
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Tidskriftsartikel (refereegranskat)abstract
- We present a new analysis of J/psi production yields in deuteron-gold collisions at root s(NN) =200 GeV using data taken from the PHENIX experiment in 2003 and previously published in S. S. Adler [Phys. Rev. Lett 96, 012304 (2006)]. The high statistics proton-proton J/psi data taken in 2005 are used to improve the baseline measurement and thus construct updated cold nuclear matter modification factors (R-dAu). A suppression of J/psi 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/psi (or precursor) breakup cross section is added. Breakup cross sections of sigma(breakup)=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.
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| 7. |
- Adare, A., et al.
(författare)
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System size and energy dependence of jet-induced hadron pair correlation shapes in Cu+Cu and Au+Au collisions at root S-NN 200 and 62.4 GeV
- 2007
-
Ingår i: Physical Review Letters. - 1079-7114. ; 98:23
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Tidskriftsartikel (refereegranskat)abstract
- We present azimuthal angle correlations of intermediate transverse momentum (1-4 GeV/c) hadrons from dijets in Cu+Cu and Au+Au collisions at root s(NN)=62.4 and 200 GeV. The away-side dijet induced azimuthal correlation is broadened, non-Gaussian, and peaked away from Delta phi=pi in central and semicentral collisions in all the systems. The broadening and peak location are found to depend upon the number of participants in the collision, but not on the collision energy or beam nuclei. These results are consistent with sound or shock wave models, but pose challenges to Cherenkov gluon radiation models.
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| 8. |
- Adare, A., et al.
(författare)
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Heavy-quark production in p plus p and energy loss and flow of heavy quarks in Au plus Au collisions at root s(NN)=200 GeV
- 2011
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 84:4
-
Tidskriftsartikel (refereegranskat)abstract
- Transverse momentum spectra of electrons (p(T)(e)) from semileptonic weak decays of heavy-flavor mesons in the range of 0.3 < p(T)(e) < 9.0 GeV/c have been measured at midrapidity (|y| < 0.35) by the PHENIX experiment at the Relativistic Heavy Ion Collider in p + p and Au + Au collisions at root s(NN) = 200 GeV. In addition, the azimuthal anisotropy parameter v(2) has been measured for 0.3 < p(T)(e) < 5.0 GeV/c in Au + Au collisions. The substantial modification in the p(T)(e) spectra in Au + Au compared with p + p collisions as well as the nonzero v(2) indicate substantial interactions and flow of heavy quarks in traversing the produced medium. Comparisons of these observables with detailed theoretical calculations can be used to identify the nature of these interactions and to quantify their extent.
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| 9. |
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| 10. |
- Adare, A., et al.
(författare)
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Correlated production of p and (p)over-bar in Au+Au collisions at root s(NN)=200 GeV
- 2007
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 649:5-6, s. 359-369
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Tidskriftsartikel (refereegranskat)abstract
- Correlations between p and (p) over bar at transverse momenta typical of enhanced baryon production in Au + Au collisions are reported. The PHENIX experiment has measured same and opposite sign baryon pairs in Au + Au collisions at root s(NN) = 200 GeV. Correlated production of p and p with the trigger particle from the range 2.5 < p(T) < 4.0 GeV/c and the associated particle with 1.8 < p(T) < 2.5 GeV/c is observed to be nearly independent of the centrality of the collisions. Same sign pairs show no correlation at any centrality. The conditional yield of mesons triggered by baryons (and anti-baryons) and mesons in the same p(T) range rises with increasing centrality, except for the most central collisions, where baryons show a significantly smaller number of associated mesons. These data are consistent with a picture in which hard scattered partons produce correlated p and (p) over bar in the p(T) region of the baryon excess. (c) 2007 Elsevier B.V. All rights reserved.
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| 11. |
- Adare, A., et al.
(författare)
-
Detailed measurement of the e(+)e(-) pair continuum in p plus p and Au plus Au collisions at root s(NN)=200 GeV and implications for direct photon production
- 2010
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 81:3
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Tidskriftsartikel (refereegranskat)abstract
- PHENIX has measured the e(+)e(-) pair continuum in root s(NN) = 200 GeV Au+Au and p+p collisions over a wide range of mass and transverse momenta. The e(+)e(-) yield is compared to the expectations from hadronic sources, based on PHENIX measurements. In the intermediate-mass region, between the masses of the phi and the J/psi meson, the yield is consistent with expectations from correlated c (c) over bar production, although other mechanisms are not ruled out. In the low-mass region, below the phi, the p+p inclusive mass spectrum is well described by known contributions from light meson decays. In contrast, the Au+Au minimum bias inclusive mass spectrum in this region shows an enhancement by a factor of 4.7 +/- 0.4(stat) +/- 1.5(syst) +/- 0.9(model). At low mass (m(ee) < 0.3 GeV/c(2)) and high p(T) (1 < p(T) < 5 GeV/c) an enhanced e(+)e(-) pair yield is observed that is consistent with production of virtual direct photons. This excess is used to infer the yield of real direct photons. In central Au+Au collisions, the excess of the direct photon yield over the p+p is exponential in p(T), with inverse slope T = 221 +/- 19(stat) +/- 19(syst) MeV. Hydrodynamical models with initial temperatures ranging from T-init similar or equal to 300-600 MeV at times of 0.6-0.15 fm/c after the collision are in qualitative agreement with the direct photon data in Au+Au. For low p(T) < 1 GeV/c the low-mass region shows a further significant enhancement that increases with centrality and has an inverse slope of T similar or equal to 100 MeV. Theoretical models underpredict the low-mass, low-p(T) enhancement.
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| 12. |
- Adare, A., et al.
(författare)
-
Dihadron azimuthal correlations in Au+Au collisions at root s(NN)=200 GeV
- 2008
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 78:1
-
Tidskriftsartikel (refereegranskat)abstract
- Azimuthal angle (Delta phi) correlations are presented for a broad range of transverse momentum (0.4 < p(T) < 10 GeV/c) and centrality (0-92%) selections for charged hadrons from dijets in Au+Au collisions at root s(NN) = 200 GeV. With increasing p(T), the away-side Delta phi distribution evolves from a broad and relatively flat shape to a concave shape, then to a convex shape. Comparisons with p + p data suggest that the away-side distribution can be divided into a partially suppressed "head" region centered at Delta phi similar to pi, and an enhanced "shoulder" region centered at Delta phi similar to pi +/- 1.1. The p(T) spectrum for the associated hadrons in the head region softens toward central collisions. The spectral slope for the shoulder region is independent of centrality and trigger p(T). The properties of the near-side distributions are also modified relative to those in p + p collisions, reflected by the broadening of the jet shape in Delta phi and Delta eta, and an enhancement of the per-trigger yield. However, these modifications seem to be limited to p(T)less than or similar to 4 GeV/c, above which both the hadron pair shape and per-trigger yield become similar to p + p collisions. These observations suggest that both the away- and near-side distributions contain a jet fragmentation component which dominates for p(T) greater than or similar to 5 GeV/c and a medium-induced component which is important for p(T) less than or similar to 4 GeV/c. We also quantify the role of jets at intermediate and low p(T) through the yield of jet-induced pairs in comparison with binary scaled p + p pair yield. The yield of jet-induced pairs is suppressed at high pair proxy energy (sum of the p(T) magnitudes of the two hadrons) and is enhanced at low pair proxy energy. The former is consistent with jet quenching; the latter is consistent with the enhancement of soft hadron pairs due to transport of lost energy to lower p(T).
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| 13. |
- Adare, A., et al.
(författare)
-
Energy loss and flow of heavy quarks in Au+Au collisions at root s(NN) = 200 GeV
- 2007
-
Ingår i: Physical Review Letters. - 1079-7114. ; 98:17
-
Tidskriftsartikel (refereegranskat)abstract
- The PHENIX experiment at the BNL Relativistic Heavy Ion Collider (RHIC) has measured electrons with 0.3 < p(T) < 9 GeV/c at midrapidity (y < 0.35) from heavy-flavor (charm and bottom) decays in Au + Au collisions at root s(NN) = 200 GeV. The nuclear modification factor R-AA relative to p + p collisions shows a strong suppression in central Au + Au collisions, indicating substantial energy loss of heavy quarks in the medium produced at RHIC energies. A large azimuthal anisotropy v(2) with respect to the reaction plane is observed for 0.5 < p(T) < 5 GeV/c indicating substantial heavy-flavor elliptic flow. Both R-AA and v(2) show a p(T) dependence different from those of neutral pions. A comparison to transport models which simultaneously describe R-AA(p(T)) and v(2)(p(T)) suggests that the viscosity to entropy density ratio is close to the conjectured quantum lower bound, i.e., near a perfect fluid.
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| 14. |
- Adare, A., et al.
(författare)
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Enhanced Production of Direct Photons in Au plus Au Collisions at root s(NN)=200 GeV and Implications for the Initial Temperature
- 2010
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Ingår i: Physical Review Letters. - 1079-7114. ; 104:13
-
Tidskriftsartikel (refereegranskat)abstract
- The production of e(+)e(-) pairs for m(e+e-) < 0.3 GeV/c(2) and 1< p(T) < 5 GeV/c is measured in p + p and Au + Au collisions at root s(NN) = 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 +/- 19(stat) +/- 19(syst) MeV. Hydrodynamical models with initial temperatures ranging from T-init similar to 300-600 MeV at times of similar to 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 similar to 170 MeV.
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| 15. |
- Adare, A., et al.
(författare)
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J/psi production versus centrality, transverse momentum, and rapidity in Au+Au collisions at root S(NN) = 200 GeV
- 2007
-
Ingår i: Physical Review Letters. - 1079-7114. ; 98:23
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Tidskriftsartikel (refereegranskat)abstract
- The PHENIX experiment at the BNL Relativistic Heavy Ion Collider (RHIC) has measured J/psi production for rapidities -2.2 < y < 2.2 in Au+Au collisions at root s(NN)=200 GeV. The J/psi invariant yield and nuclear modification factor R-AA as a function of centrality, transverse momentum, and rapidity are reported. A suppression of J/psi relative to binary collision scaling of proton-proton reaction yields is observed. Models which describe the lower energy J/psi data at the CERN Super Proton Synchrotron invoking only J/psi destruction based on the local medium density predict a significantly larger suppression at RHIC and more suppression at midrapidity than at forward rapidity. Both trends are contradicted by our data.
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| 16. |
- Adare, A., et al.
(författare)
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Quantitative constraints on the transport properties of hot partonic matter from semi-inclusive single high transverse momentum pion suppression in Au plus Au collisions at root S-NN=200 GeV
- 2008
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 77:6
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Tidskriftsartikel (refereegranskat)abstract
- The PHENIX experiment has measured the suppression of semi-inclusive single high-transverse-momentum pi(0)'s in Au+Au collisions at root s(NN) = 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 dN(g)/dy, the medium transport coefficient <(q) over cap >, or the initial energy-loss parameter epsilon(0). We find that high-transverse-momentum pi(0) 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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| 17. |
- Adare, A., et al.
(författare)
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Scaling properties of azimuthal anisotropy in Au plus Au and Cu plus Cu collisions at root s(NN)=200 GeV
- 2007
-
Ingår i: Physical Review Letters. - 1079-7114. ; 98:16
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Tidskriftsartikel (refereegranskat)abstract
- Differential measurements of elliptic flow (v(2)) for Au+Au and Cu+Cu collisions at root s(NN)=200 GeV are used to test and validate predictions from perfect fluid hydrodynamics for scaling of v(2) with eccentricity, system size, and transverse kinetic energy (KET). For KET equivalent to m(T)-m up to similar to 1 GeV the scaling is compatible with hydrodynamic expansion of a thermalized fluid. For large values of KET mesons and baryons scale separately. Quark number scaling reveals a universal scaling of v(2) for both mesons and baryons over the full KET range for Au+Au. For Au+Au and Cu+Cu the scaling is more pronounced in terms of KET, rather than transverse momentum.
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| 18. |
- Adare, A., et al.
(författare)
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Systematic study of azimuthal anisotropy in Cu plus Cu and Au plus Au collisions at root s(NN)=62.4 and 200 GeV
- 2015
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 92:3
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the dependence of azimuthal anisotropy nu(2) for inclusive and identified charged hadrons in Au + Au and Cu + Cu collisions on collision energy, species, and centrality. The values of nu(2) as a function of transverse momentum pT and centrality in Au + Au collisions at root s(NN) = 200 and 62.4 GeV are the same within uncertainties. However, in Cu + Cu collisions we observe a decrease in nu(2) values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both Au + Au and Cu + Cu collisions we find that nu(2) depends both on eccentricity and the number of participants, N-part. We observe that nu(2) divided by eccentricity (epsilon) monotonically increases with N-part and scales as N-part(1/3). The Cu + Cu data at 62.4 GeV falls below the other scaled nu(2) data. For identified hadrons, nu(2) divided by the number of constituent quarks n(q) is independent of hadron species as a function of transverse kinetic energy K E-T = m(T) - m between 0.1 < K E-T / n(q) < 1 GeV. Combining all of the above scaling and normalizations, we observe a near-universal scaling, with the exception of the Cu + Cu data at 62.4 GeV, of nu(2)/(nq center dot e center dot N-part(1/3)) vs K E-T / n(q) for all measured particles.
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| 19. |
- Adare, A., et al.
(författare)
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Transverse momentum and centrality dependence of dihadron correlations in Au plus Au collisions at root s(NN)=200 GeV: Jet quenching and the response of partonic matter
- 2008
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 77:1, s. 6-011901
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Tidskriftsartikel (refereegranskat)abstract
- Azimuthal angle (Delta phi) correlations are presented for charged hadrons from dijets for 0.4 < p(T)< 10 GeV/c in Au+Au collisions at root s(NN)=200 GeV. With increasing p(T), the away-side distribution evolves from a broad and relatively flat shape to a concave shape, then to a convex shape. Comparisons to p+p data suggest that the away-side can be divided into a partially suppressed "head" region centered at Delta phi similar to pi and an enhanced "shoulder" region centered at Delta phi similar to pi +/- 1.1. The p(T) spectrum for the head region softens toward central collisions, consistent with the onset of jet quenching. The spectral slope for the shoulder region is independent of centrality and trigger p(T), which offers constraints on energy transport mechanisms and suggests that it contains the medium response to energetic jets.
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| 20. |
- Adler, S. S., et al.
(författare)
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Transverse-energy distributions at midrapidity in p plus p, d plus Au, and Au plus Au collisions at root s(NN)=62.4-200 GeV and implications for particle-production models
- 2014
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 89:4
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of the midrapidity transverse-energy distribution, dE(T)/d eta, are presented for p + p, d+Au, and Au+Au collisions atv root s(NN) = 200 GeV and additionally for Au+Au collisions atv root s(NN) = 62.4 and 130 GeV. The dE(T)/d eta distributions are first compared with the number of nucleon participants N-part, number of binary collisions N-coll, and number of constituent-quark participants N-qp calculated from a Glauber model based on the nuclear geometry. For Au+Au, < dE(T)/d eta >/N-part increases with N-part, while < dE(T)/d eta >/N-qp is approximately constant for all three energies. This indicates that the two-component ansatz, dE(T)/d eta alpha (1 - x)N-part/2 + xN(coll), which was used to represent E-T distributions, is simply a proxy for N-qp, and that the N-coll term does not represent a hard-scattering component in E-T distributions. The dE(T)/d eta distributions of Au+Au and d+Au are then calculated from the measured p + p E-T distribution using two models that both reproduce the Au+Au data. However, while the number-of-constituent-quark-participant model agrees well with the d+Au data, the additive-quark model does not.
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| 21. |
- Adler, S. S., et al.
(författare)
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High transverse momentum eta meson production in p+p, d+Au, and Au+Au collisions at root s(NN)=200 GeV
- 2007
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 75:2
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Forskningsöversikt (refereegranskat)abstract
- Inclusive transverse momentum spectra of eta mesons in the range p(T)approximate to 2-12 GeV/c have been measured at midrapidity (vertical bar eta vertical bar < 0.35) by the PHENIX experiment at RHIC in p+p,d+Au, and Au+Au collisions at root s(NN)=200 GeV. The eta mesons are reconstructed through their eta ->gamma gamma channel for the three colliding systems as well as through the eta ->pi(0)pi(+)pi(-) decay mode in p+p and d+Au collisions. The nuclear modification factor in d+Au collisions, R-dAu(p(T))approximate to 1.0-1.1, suggests at most only modest p(T) broadening ("Cronin enhancement"). In central Au+Au reactions, the eta yields are significantly suppressed, with R-AuAu(p(T))approximate to 0.2. The ratio of eta to pi(0) yields is approximately constant as a function of p(T) for the three colliding systems in agreement with the high-p(T) world average of R-eta/pi(0)approximate to 0.5 in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions for a wide range of center-of-mass energies (root sNN approximate to 3-1800 GeV) as well as, for high scaled momentum x(p), in e(+)e(-) annihilations at root s=91.2 GeV. These results are consistent with a scenario where high-p(T) eta production in nuclear collisions at the Relativistic Heavy Ion Collider is largely unaffected by initial-state effects but where light-quark mesons (pi(0),eta) are equally suppressed due to final-state interactions of the parent partons in the dense medium produced in Au+Au reactions.
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| 22. |
- Adler, S. S., et al.
(författare)
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Azimuthal angle correlations for rapidity separated hadron pairs in d+Au collisions at root s(NN)=200 GeV
- 2006
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Ingår i: Physical Review Letters. - 1079-7114. ; 96:22
-
Tidskriftsartikel (refereegranskat)abstract
- Deuteron-gold (d+Au) collisions at the Relativistic Heavy Ion Collider provide ideal platforms for testing QCD theories in dense nuclear matter at high energy. In particular, models suggesting strong saturation effects for partons carrying small nucleon momentum fraction (x) predict modifications to jet production at forward rapidity (deuteron-going direction) in d+Au collisions. We report on two-particle azimuthal angle correlations between charged hadrons at forward/backward (deuteron/gold going direction) rapidity and charged hadrons at midrapidity in d+Au and p+p collisions at root s(NN)=200 GeV. Jet structures observed in the correlations are quantified in terms of the conditional yield and angular width of away-side partners. The kinematic region studied here samples partons in the gold nucleus with x similar to 0.1 to similar to 0.01. Within this range, we find no x dependence of the jet structure in d+Au collisions.
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| 23. |
- Adler, S. S., et al.
(författare)
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Centrality dependence of charged hadron production in deuteron plus gold and nucleon plus gold collisions at root S-NN=200 GeV
- 2008
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 77:1
-
Tidskriftsartikel (refereegranskat)abstract
- We present transverse momentum (p(T)) spectra of charged hadrons measured in deuteron-gold and nucleon-gold collisions at root s(NN)=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, nu, 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 nu for high momentum particles. We also present the charged hadron to neutral pion ratios as a function of p(T).
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| 24. |
- Adler, S. S., et al.
(författare)
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Centrality dependence of pi(0) and eta production at large transverse momentum in root s(NN) = 200 GeV d+Au collisions
- 2007
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Ingår i: Physical Review Letters. - 1079-7114. ; 98:17
-
Tidskriftsartikel (refereegranskat)abstract
- The dependence of transverse momentum spectra of neutral pions and eta mesons with p(T) < 16 GeV/c and p(T) < 12 GeV/c, respectively, on the centrality of the collision has been measured at midrapidity by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider (RHIC) in d + Au collisions at root s(NN) = 200 GeV. The measured yields are compared to those in p + p collisions at the same root s(NN) scaled by the number of underlying nucleon-nucleon collisions in d + Au. At all centralities, the yield ratios show no suppression, in contrast to the strong suppression seen for central An + Au collisions at RHIC. Only a weak p(T) and centrality dependence can be observed.
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| 25. |
- Adler, S. S., et al.
(författare)
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Jet properties from dihadron correlations in p plus p collisions at root s=200 GeV
- 2006
-
Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 74:7
-
Tidskriftsartikel (refereegranskat)abstract
- The properties of jets produced in p+p collisions at root s=200 GeV are measured using the method of two-particle correlations. The trigger particle is a leading particle from a large transverse momentum jet while the associated particle comes from either the same jet or the away-side jet. Analysis of the angular width of the near-side peak in the correlation function determines the jet-fragmentation transverse momentum j(T). The extracted value, root < j(T)(2)>=585 +/- 6(stat)+/- 15(sys) MeV/c, is constant with respect to the trigger particle transverse momentum, and comparable to the previous lower root s measurements. The width of the away-side peak is shown to be a convolution of j(T) with the fragmentation variable, z, and the partonic transverse momentum, k(T). The < z > is determined through a combined analysis of the measured pi(0) inclusive and associated spectra using jet-fragmentation functions measured in e(+)e(-) collisions. The final extracted values of k(T) are then determined to also be independent of the trigger particle transverse momentum, over the range measured, with value of root < k(T)(2)>=2.68 +/- 0.07(stat)+/- 0.34(sys) GeV/c.
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| 26. |
- Adler, S. S., et al.
(författare)
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Jet structure from dihadron correlations in d+Au collisions at root S-NN=200 GeV
- 2006
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 73:5
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Tidskriftsartikel (refereegranskat)abstract
- Dihadron correlations at high transverse momentum p(T) in d+Au collisions at root s(NN)=200 GeV at midrapidity are measured by the PHENIX experiment at the Relativistic Heavy Ion Collider. From these correlations, we extract several structural characteristics of jets: the root-mean-squared transverse momentum of fragmenting hadrons with respect to the jet root < j(T)(2)>, the mean sine-squared of the azimuthal angle between the jet axes < sin(2)phi(jj)>, and the number of particles produced within the dijet that are associated with a high-p(T) particle (dN/dx(E) distributions). We observe that the fragmentation characteristics of jets in d+Au collisions are very similar to those in p+p collisions and that there is little dependence on the centrality of the d+Au collision. This is consistent with the nuclear medium having little influence on the fragmentation process. Furthermore, there is no statistically significant increase in the value of < sin(2)phi(jj)> from p+p to d+Au collisions. This constrains the effect of multiple scattering that partons undergo in the cold nuclear medium before and after a hard collision.
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| 27. |
- Adler, S. S., et al.
(författare)
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Measurement of direct photon production in p+p collisions at root s=200 GeV
- 2007
-
Ingår i: Physical Review Letters. - 1079-7114. ; 98:1
-
Tidskriftsartikel (refereegranskat)abstract
- Cross sections for midrapidity production of direct photons in p+p collisions at the Relativistic Heavy Ion Collider (RHIC) are reported for transverse momenta of 3 < p(T)< 16 GeV/c. Next-to-leading order perturbative QCD (pQCD) describes the data well for p(T)> 5 GeV/c, where the uncertainties of the measurement and theory are comparable. We also report on the effect of requiring the photons to be isolated from parton jet energy. The observed fraction of isolated photons is well described by pQCD for p(T)> 7 GeV/c.
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| 28. |
- Adler, S. S., et al.
(författare)
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Nuclear effects on hadron production in d plus Au collisions at root S-NN=200 GeV revealed by comparison with p plus p data
- 2006
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 74:2
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Tidskriftsartikel (refereegranskat)abstract
- PHENIX has measured the centrality dependence of midrapidity pion, kaon, and proton transverse momentum distributions in d+Au and p+p collisions at root s(NN) = 200 GeV. The p+p data provide a reference for nuclear effects in d+Au and previously measured Au+Au collisions. Hadron production is enhanced in d+Au, relative to independent nucleon-nucleon scattering, as was observed in lower energy collisions. The nuclear modification factor for (anti)protons is larger than that for pions. The difference increases with centrality but is not sufficient to account for the abundance of baryon production observed in central Au+Au collisions at the BNL Relativistic Heavy Ion Collider (RHIC). The centrality dependence in d+Au shows that the nuclear modification factor increases gradually with the number of collisions encountered by each participant nucleon. We also present comparisons with lower energy data as well as with parton recombination and other theoretical models of nuclear effects on particle production.
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| 29. |
- Adler, S. S., et al.
(författare)
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Production of omega mesons at large transverse momenta in p+p and d+Au collisions at root S(NN) = 200 GeV
- 2007
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 75:5
-
Tidskriftsartikel (refereegranskat)abstract
- The PHENIX experiment at RHIC has measured the invariant cross section for omega-meson production at midrapidity in the transverse momentum range 2.5 < p(T)< 9.25 GeV/c in p+p and d+Au collisions at root s(NN) = 200 GeV. Measurements in two decay channels (omega ->pi(0)pi(+)pi(-) and omega ->pi(0)gamma) yield consistent results, and the reconstructed omega mass agrees with the accepted value within the p(T) range of the measurements. The omega/pi(0) ratio is found to be 0.85 +/- 0.05(stat)+/- 0.09(sys) in p+p and 0.94 +/- 0.08(stat)+/- 0.12(sys) in d+Au collisions, independent of p(T). The nuclear modification factor R-dA(omega) is 1.03 +/- 0.12(stat)+/- 0.21(sys) and 0.83 +/- 0.21(stat)+/- 0.17(sys) in minimum bias and central (0-20%) d+Au collisions, respectively.
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| 30. |
- Afanasiev, S., et al.
(författare)
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Systematic studies of elliptic flow measurements in Au plus Au collisions at s(NN)=200 GeV
- 2009
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:2
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Tidskriftsartikel (refereegranskat)abstract
- We present inclusive charged hadron elliptic flow (v(2)) measured over the pseudorapidity range vertical bar eta vertical bar < 0.35 in Au+Au collisions at s(NN)=200 GeV. Results for v(2) 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 v(2), we compare two different analysis methods: (1) the event-plane method from two independent subdetectors at forward (vertical bar eta vertical bar=3.1-3.9) and beam (vertical bar eta vertical bar>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 v(2) 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.
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| 31. |
- Afanasiev, S., et al.
(författare)
-
Charged Kaon Interferometric Probes of Space-Time Evolution in Au plus Au Collisions at s(NN)=200 GeV
- 2009
-
Ingår i: Physical Review Letters. - 1079-7114. ; 103:14
-
Tidskriftsartikel (refereegranskat)abstract
- 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 greater than or similar to 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.
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| 32. |
- Afanasiev, S., et al.
(författare)
-
Elliptic flow for phi mesons and (Anti)deuterons in Au+Au collisions at root s(NN)=200 GeV
- 2007
-
Ingår i: Physical Review Letters. - 1079-7114. ; 99:5
-
Tidskriftsartikel (refereegranskat)abstract
- Differential elliptic flow (v(2)) for phi mesons and (anti)deuterons ((d) over bar )d is measured for Au + Au collisions at root s(NN) = 200 GeV. The v(2) for phi mesons follows the trend of lighter pi(+/-) and K-+/- mesons, suggesting that ordinary hadrons interacting with standard hadronic cross sections are not the primary driver for elliptic flow development. The v(2) values for ((d) over bar )d suggest that elliptic flow is additive for composite particles. This further validation of the universal scaling of v(2) per constituent quark for baryons and mesons suggests that partonic collectivity dominates the transverse expansion dynamics.
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| 33. |
- Afanasiev, S., et al.
(författare)
-
High-p(T) pi(0) production with respect to the reaction plane in Au plus Au collisions at s(NN)=200 GeV
- 2009
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:5
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of the azimuthal anisotropy of high-p(T) neutral pion (pi(0)) 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 pi(0) 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 (v(2)) of the angular distributions are presented as a function of pi(0) transverse momentum (p(T)) for different bins in collision centrality. Measured reaction plane dependent pi(0) yields are used to determine the azimuthal dependence of the pi(0) suppression as a function of p(T), R-AA(Delta phi,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 pi(0) 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.
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| 34. |
- Afanasiev, S., et al.
(författare)
-
Measurement of Direct Photons in Au plus Au Collisions at root s(NN)=200 GeV
- 2012
-
Ingår i: Physical Review Letters. - 1079-7114. ; 109:15
-
Tidskriftsartikel (refereegranskat)abstract
- We report the measurement of direct photons at midrapidity in Au + Au collisions at root s(NN) = 200 GeV. The direct photon signal was extracted for the transverse momentum range of 4 GeV/c < pT < 22 GeV/c, using a statistical method to subtract decay photons from the inclusive photon sample. The direct photon nuclear modification factor R-AA was calculated as a function of p(T) for different Au + Au collision centralities using the measured p + p direct photon spectrum and compared to theoretical predictions. R-AA was found to be consistent with unity for all centralities over the entire measured pT range. Theoretical models that account for modifications of initial direct photon production due to modified parton distribution functions in Au and the different isospin composition of the nuclei predict a modest change of R-AA from unity. They are consistent with the data. Models with compensating effects of the quark-gluon plasma on high-energy photons, such as suppression of jet-fragmentation photons and induced-photon bremsstrahlung from partons traversing the medium, are also consistent with this measurement.
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| 35. |
- Afanasiev, S., et al.
(författare)
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Particle-species dependent modification of jet-induced correlations in Au plus Au collisions at root s(NN)=200 GeV
- 2008
-
Ingår i: Physical Review Letters. - 1079-7114. ; 101:8
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements in Au + Au collisions at root 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.
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| 36. |
- Afanasiev, S., et al.
(författare)
-
Photoproduction of J/psi and of high mass e(+)e(-) in ultra-peripheral Au plus Au collisions at root s(NN)=200 GeV
- 2009
-
Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 679:4, s. 321-329
-
Tidskriftsartikel (refereegranskat)abstract
- We present the first measurement of photoproduction of J/psi and of two-photon production of high-mass e(+)e(-) pairs in electromagnetic (or ultra-peripheral) nucleus-nucleus interactions, using Au + Au data at root s(NN) = 200 GeV. The events are tagged with forward neutrons emitted following Coulomb excitation of one or both Au* nuclei. The event sample consists of 28 events with m(e+e-) > 2 GeV/c(2) with zero like-sign background. The measured cross sections at midrapidity of d sigma/dy (J/psi + Xn, y = 0) = 76 +/- 33 (stat) +/- 11 (syst) pb and d(2)sigma /dm dy (e(+) e(-) + Xn, y = 0) = 86 +/- 23(stat) +/- 16(syst) mu b/ (GeV/c(2)) for m(e+e-) epsilon vertical bar 2.0, 2.8 vertical bar GeV/c(2) have been compared and found to be consistent with models for photoproduction of J/psi and QED based calculations of two-photon production of e(+)e(-) pairs. (C) 2009 Elsevier B.V. All rights reserved.
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| 37. |
- Afanasiev, S., et al.
(författare)
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Source breakup dynamics in Au+Au collisions at root s(NN)=200 GeV via three-dimensional two-pion source imaging
- 2008
-
Ingår i: Physical Review Letters. - 1079-7114. ; 100:23
-
Tidskriftsartikel (refereegranskat)abstract
- A three-dimensional correlation function obtained from midrapidity, low p(T), pion pairs in central Au+Au collisions at root 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 tau(0) similar to 9 fm/c and a mean proper emission duration Delta tau similar to 2 fm/c, leading to sizable emission time differences ( approximate to 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.
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| 38. |
- Adcox, K, et al.
(författare)
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Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX Collaboration
- 2005
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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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| 39. |
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| 40. |
- Adler, SS, et al.
(författare)
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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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| 41. |
- 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
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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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| 42. |
- Ruggeri, Kai, et al.
(författare)
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The globalizability of temporal discounting
- 2022
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Ingår i: Nature Human Behaviour. - : Springer Nature. - 2397-3374. ; 6:10, s. 1386-1397
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Tidskriftsartikel (refereegranskat)abstract
- Economic inequality is associated with preferences for smaller, immediate gains over larger, delayed ones. Such temporal discounting may feed into rising global inequality, yet it is unclear whether it is a function of choice preferences or norms, or rather the absence of sufficient resources for immediate needs. It is also not clear whether these reflect true differences in choice patterns between income groups. We tested temporal discounting and five intertemporal choice anomalies using local currencies and value standards in 61 countries (N = 13,629). Across a diverse sample, we found consistent, robust rates of choice anomalies. Lower-income groups were not significantly different, but economic inequality and broader financial circumstances were clearly correlated with population choice patterns. Ruggeri et al. find in a study of 61 countries that temporal discounting patterns are globally generalizable. Worse financial environments, greater inequality and high inflation are associated with extreme or inconsistent long-term decisions.
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| 43. |
- Wallace, Bryan P., et al.
(författare)
-
Global Conservation Priorities for Marine Turtles
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:9
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Tidskriftsartikel (refereegranskat)abstract
- Where conservation resources are limited and conservation targets are diverse, robust yet flexible priority-setting frameworks are vital. Priority-setting is especially important for geographically widespread species with distinct populations subject to multiple threats that operate on different spatial and temporal scales. Marine turtles are widely distributed and exhibit intra-specific variations in population sizes and trends, as well as reproduction and morphology. However, current global extinction risk assessment frameworks do not assess conservation status of spatially and biologically distinct marine turtle Regional Management Units (RMUs), and thus do not capture variations in population trends, impacts of threats, or necessary conservation actions across individual populations. To address this issue, we developed a new assessment framework that allowed us to evaluate, compare and organize marine turtle RMUs according to status and threats criteria. Because conservation priorities can vary widely (i.e. from avoiding imminent extinction to maintaining long-term monitoring efforts) we developed a "conservation priorities portfolio" system using categories of paired risk and threats scores for all RMUs (n = 58). We performed these assessments and rankings globally, by species, by ocean basin, and by recognized geopolitical bodies to identify patterns in risk, threats, and data gaps at different scales. This process resulted in characterization of risk and threats to all marine turtle RMUs, including identification of the world's 11 most endangered marine turtle RMUs based on highest risk and threats scores. This system also highlighted important gaps in available information that is crucial for accurate conservation assessments. Overall, this priority-setting framework can provide guidance for research and conservation priorities at multiple relevant scales, and should serve as a model for conservation status assessments and priority-setting for widespread, long-lived taxa.
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| 44. |
- Wallace, Bryan P., et al.
(författare)
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Regional Management Units for Marine Turtles: A Novel Framework for Prioritizing Conservation and Research across Multiple Scales
- 2010
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:12
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Resolving threats to widely distributed marine megafauna requires definition of the geographic distributions of both the threats as well as the population unit(s) of interest. In turn, because individual threats can operate on varying spatial scales, their impacts can affect different segments of a population of the same species. Therefore, integration of multiple tools and techniques - including site-based monitoring, genetic analyses, mark-recapture studies and telemetry - can facilitate robust definitions of population segments at multiple biological and spatial scales to address different management and research challenges. Methodology/Principal Findings: To address these issues for marine turtles, we collated all available studies on marine turtle biogeography, including nesting sites, population abundances and trends, population genetics, and satellite telemetry. We georeferenced this information to generate separate layers for nesting sites, genetic stocks, and core distributions of population segments of all marine turtle species. We then spatially integrated this information from fine-to coarse-spatial scales to develop nested envelope models, or Regional Management Units (RMUs), for marine turtles globally. Conclusions/Significance: The RMU framework is a solution to the challenge of how to organize marine turtles into units of protection above the level of nesting populations, but below the level of species, within regional entities that might be on independent evolutionary trajectories. Among many potential applications, RMUs provide a framework for identifying data gaps, assessing high diversity areas for multiple species and genetic stocks, and evaluating conservation status of marine turtles. Furthermore, RMUs allow for identification of geographic barriers to gene flow, and can provide valuable guidance to marine spatial planning initiatives that integrate spatial distributions of protected species and human activities. In addition, the RMU framework - including maps and supporting metadata - will be an iterative, user-driven tool made publicly available in an online application for comments, improvements, download and analysis.
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| 45. |
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| 46. |
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| 47. |
- Casper, C, et al.
(författare)
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Coreceptor usage of primary HIV type 1 isolates obtained from different lymph node subsets
- 2005
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Ingår i: AIDS Research and Human Retroviruses. - : Mary Ann Liebert Inc. - 1931-8405 .- 0889-2229. ; 21:12, s. 1003-1010
-
Tidskriftsartikel (refereegranskat)abstract
- Biological characteristics of virus quantitatively rescued from different cell types present in lymph nodes of HIV-1-infected individuals in various stages of their disease were determined, not including patients with AIDS defining illness. Viruses were obtained by cocultivation with donor monocyte-derived macrophages and T-lymphocytes and their biological phenotype compared to viruses obtained from the peripheral blood mononuclear cells of the same patient. The biological phenotype was determined on established cell lines (U937-2, CEM, and MT-2) and on the U87.CD4 coreceptor indicator cell lines and variable region 3 (V3) of the envelope was subjected to direct sequencing. All isolates obtained from lymph node subsets used CCR5 as coreceptor. Furthermore, these viruses were also sensitive to inhibition by beta-chemokines as analyzed for viruses of one patient. All 12 V3 regions showed a unique sequence indicating compartmentalization within each patient. The biological phenotype of CCR5-dependent (R5) HIV-1 isolates obtained from PBMC resembles the phenotype of viruses isolated from different lymph node cell subsets.
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| 48. |
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| 49. |
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| 50. |
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