| 1. |
- Adare, A., et al.
(author)
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Lévy-stable two-pion Bose-Einstein correlations in s NN =200 GeV Au+Au collisions
- 2018
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In: Physical Review C. - 2469-9985. ; 97:6
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Journal article (peer-reviewed)abstract
- We present a detailed measurement of charged two-pion correlation functions in 0-30% centrality sNN=200 GeV Au+Au collisions by the PHENIX experiment at the Relativistic Heavy Ion Collider. The data are well described by Bose-Einstein correlation functions stemming from Lévy-stable source distributions. Using a fine transverse momentum binning, we extract the correlation strength parameter λ, the Lévy index of stability α, and the Lévy length scale parameter R as a function of average transverse mass of the pair mT. We find that the positively and the negatively charged pion pairs yield consistent results, and their correlation functions are represented, within uncertainties, by the same Lévy-stable source functions. The λ(mT) measurements indicate a decrease of the strength of the correlations at low mT. The Lévy length scale parameter R(mT) decreases with increasing mT, following a hydrodynamically predicted type of scaling behavior. The values of the Lévy index of stability α are found to be significantly lower than the Gaussian case of α=2, but also significantly larger than the conjectured value that may characterize the critical point of a second-order quark-hadron phase transition. © 2018 American Physical Society.
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| 2. |
- Adare, A, et al.
(author)
-
Measurements of directed, elliptic, and triangular flow in Cu + Au collisions at s NN =200 GeV MEASUREMENTS of DIRECTED, ELLIPTIC, and ... A. ADARE et al.
- 2016
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In: Physical Review C: covering nuclear physics. - 2469-9985. ; 94:5
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Journal article (peer-reviewed)abstract
- Measurements of anisotropic flow Fourier coefficients (vn) for inclusive charged particles and identified hadrons π±, K±, p, and p produced at midrapidity in Cu+Au collisions at sNN=200 GeV are presented. The data were collected in 2012 by the PHENIX experiment at the Relativistic Heavy-Ion Collider (RHIC). The particle azimuthal distributions with respect to different-order symmetry planes Ψn, for n=1, 2, and 3 are studied as a function of transverse momentum pT over a broad range of collision centralities. Mass ordering, as expected from hydrodynamic flow, is observed for all three harmonics. The charged-particle results are compared with hydrodynamical and transport model calculations. We also compare these Cu+Au results with those in Cu+Cu and Au+Au collisions at the same sNN and find that the v2 and v3, as a function of transverse momentum, follow a common scaling with 1/(nNpart1/3). © 2016 American Physical Society.
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| 3. |
- Aidala, C., et al.
(author)
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B -meson production at forward and backward rapidity in p+p and Cu + Au collisions at sNN =200 GeV
- 2017
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In: Physical Review C. - 2469-9985. ; 96:6
-
Journal article (peer-reviewed)abstract
- The fraction of J/ψ mesons which come from B-meson decay, FB→J/ψ, is measured for J/ψ rapidity 1.20 in p+p and Cu+Au collisions at sNN = 200 GeV with the PHENIX detector. The extracted fraction is FB→J/ψ=0.025±0.006 (stat) ± 0.010(syst) for p+p collisions. For Cu+Au collisions, FB→J/ψ is 0.094 ± 0.028(stat) ± 0.037(syst) in the Au-going direction (-2.2
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| 4. |
- Aidala, C., et al.
(author)
-
Cross section and transverse single-spin asymmetry of muons from open heavy-flavor decays in polarized p+p collisions at s =200 GeV
- 2017
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In: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-2368. ; 95:11
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Journal article (peer-reviewed)abstract
- The cross section and transverse single-spin asymmetries of μ- and μ+ from open heavy-flavor decays in polarized p+p collisions at s=200 GeV were measured by the PHENIX experiment during 2012 at the Relativistic Heavy Ion Collider. Because heavy-flavor production is dominated by gluon-gluon interactions at s=200 GeV, these measurements offer a unique opportunity to obtain information on the trigluon correlation functions. The measurements are performed at forward and backward rapidity (1.4
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| 5. |
- Adare, A, et al.
(author)
-
Azimuthal-Angle Dependence of Charged-Pion-Interferometry Measurements with Respect to Second- and Third-Order Event Planes in Au+Au Collisions at sqrt[s_{NN}]=200 GeV.
- 2014
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In: Physical Review Letters. - 1079-7114. ; 112:22
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Journal article (peer-reviewed)abstract
- Charged-pion-interferometry measurements were made with respect to the second- and third-order event plane for Au+Au collisions at sqrt[s_{NN}]=200 GeV. A strong azimuthal-angle dependence of the extracted Gaussian-source radii was observed with respect to both the second- and third-order event planes. The results for the second-order dependence indicate that the initial eccentricity is reduced during the medium evolution, which is consistent with previous results. In contrast, the results for the third-order dependence indicate that the initial triangular shape is significantly reduced and potentially reversed by the end of the medium evolution, and that the third-order oscillations are largely dominated by the dynamical effects from triangular flow.
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| 6. |
- Adare, A., et al.
(author)
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Azimuthal anisotropy of pi(0) and eta mesons in Au plus Au collisions at root s(NN)=200 GeV
- 2013
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 88:6
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Journal article (peer-reviewed)abstract
- The azimuthal anisotropy coefficients v2 and v4 of p 0 and. mesons are measured in Au + Au collisions at root s(NN) = 200 GeV as a function of transverse momentum p(T) (1-14 GeV/c) and centrality. The extracted v(2) coefficients are found to be consistent between the two meson species over the measured p(T) range. The ratio of v(4)/v(2)(2) for pi(0) mesons is found to be independent of p(T) for 1- 9 GeV/c, implying a lack of sensitivity of the ratio to the change of underlying physics with p(T). Furthermore, the ratio of v(4)/v(2)(2) is systematically larger in central collisions, which may reflect the combined effects of fluctuations in the initial collision geometry and finite viscosity in the evolving medium.
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| 7. |
- Adare, A., et al.
(author)
-
Azimuthal correlations of electrons from heavy-flavor decay with hadrons in p plus p and Au plus Au collisions at root s(NN)=200 GeV
- 2011
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 83:4
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Journal article (peer-reviewed)abstract
- Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled p+p collisions. These measurements indicate that charm and bottom quarks interact with the hot dense matter produced in heavy-ion collisions much more than expected. Here we extend these studies to two-particle correlations where one particle is an electron from the decay of a heavy-flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interactions between heavy quarks and the matter, such as whether the modification of the away-side-jet shape seen in hadron-hadron correlations is present when the trigger particle is from heavy-meson decay and whether the overall level of away-side-jet suppression is consistent. We statistically subtract correlations of electrons arising from background sources from the inclusive electron-hadron correlations and obtain two-particle azimuthal correlations at root s(NN) = 200 GeV between electrons from heavy-flavor decay with charged hadrons in p+p and also first results in Au+Au collisions. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to p+p collisions.
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| 8. |
- Adare, A., et al.
(author)
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Centrality categorization Rp(d)+A in high-energy collisions
- 2014
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 90:3
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Journal article (peer-reviewed)abstract
- High-energy proton- and deuteron-nucleus collisions provide an excellent tool for studying a wide array of physics effects, including modifications of parton distribution functions in nuclei, gluon saturation, and color neutralization and hadronization in a nuclear environment, among others. All of these effects are expected to have a significant dependence on the size of the nuclear target and the impact parameter of the collision, also known as the collision centrality. In this article, we detail a method for determining centrality classes in p(d) + A collisions via cuts on the multiplicity at backward rapidity (i.e., the nucleus-going direction) and for determining systematic uncertainties in this procedure. For d + Au collisions at root s(NN) = 200 GeV we find that the connection to geometry is confirmed by measuring the fraction of events in which a neutron from the deuteron does not interact with the nucleus. As an application, we consider the nuclear modification factors Rp(d)+A, for which there is a bias in the measured centrality-dependent yields owing to auto correlations between the process of interest and the backward-rapidity multiplicity. We determine the bias-correction factors within this framework. This method is further tested using the HIJING Monte Carlo generator. We find that for d + Au collisions at root s(NN) = 200 GeV, these bias corrections are small and vary by less than 5% (10%) up to p(T) = 10 (20) GeV/c. In contrast, for p + Pb collisions at v root s(NN) = 5.02 TeV we find that these bias factors are an order of magnitude larger and strongly pT dependent, likely attributable to the larger effect of multiparton interactions.
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| 9. |
- Adare, A., et al.
(author)
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Centrality dependence of low-momentum direct-photon production in Au plus Au collisions at root s(NN)=200 GeV
- 2015
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 91:6
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Journal article (peer-reviewed)abstract
- The PHENIX experiment at RHIC has measured the centrality dependence of the direct photon yield from Au + Au collisions at root s(NN) = 200 GeV down to pT = 0.4 GeV/c. Photons are detected via photon conversions to e(+)e(-) pairs and an improved technique is applied that minimizes the systematic uncertainties that usually limit direct photon measurements, in particular at low pT. We find an excess of direct photons above the N-coll-scaled yield measured in p + p collisions. This excess yield is well described by an exponential distribution with an inverse slope of about 240 MeV/c in the pT range 0.6-2.0 GeV/c. While the shape of the pT distribution is independent of centrality within the experimental uncertainties, the yield increases rapidly with increasing centrality, scaling approximately with N-part(alpha), where alpha = 1.38 +/- 0.03(stat) +/- 0.07(syst).
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| 10. |
- Adare, A., et al.
(author)
-
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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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 78:4
-
Journal article (peer-reviewed)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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