The initial conditions in heavy-ion collisions are calculated in many different frameworks. The importance of nucleon position fluctuations within the nucleus and subnucleon structure has been ...established when modeling initial conditions for input to hydrodynamic calculations. However, there remain outstanding puzzles regarding these initial conditions, including the measurement of the near equivalence of the elliptical v2 and triangular v3 flow coefficients in ultracentral 0–1% Pb + Pb collisions at the CERN Large Hadron Collider. Recently a calculation termed magma incorporating gluonic hot spots via two-point correlators in the color glass condensate framework, and no nucleons, provided a simultaneous match to these flow coefficients measured by the ATLAS experiment, including in ultracentral 0–1% collisions. Our calculations reveal that the magma initial conditions do not describe the experimental data when run through full hydrodynamic sonic simulations or when the hot spots from one nucleus resolve hot spots from the other nucleus, as predicted in the color glass condensate framework. Finally, we also explore alternative initial condition calculations and discuss their implications.
We study the temperature profile, pion spectra, and HBT radii in central, symmetric, and boost-invariant nuclear collisions, using a super hybrid model for heavy-ion collisions (SONIC), combining ...pre-equilibrium flow with viscous hydrodynamics and late-stage hadronic rescatterings. In particular, we simulate Pb + Pb collisions at
s
=
2.76
TeV, Au + Au, Cu + Cu, Al + Al, and C + C collisions at
s
=
200
GeV, and Au + Au and Cu + Cu collisions at
s
=
62.4
GeV. We find that SONIC provides a good match to the pion spectra and HBT radii for all collision systems and energies, confirming earlier work that a combination of pre-equilibrium flow, viscosity, and QCD equation of state can resolve the so-called HBT puzzle. For reference, we also show p + p collisions at
s
=
7
TeV. We make tabulated data for the 2 + 1 dimensional temperature evolution of all systems publicly available for the use in future jet energy loss or similar studies.
Recently the PHENIX Collaboration has made available two-particle correlation Fourier coefficients for multiple detector combinations in minimum bias p+p and 0–5% central p+Au, d+Au, and 3He+Au ...collisions at √sNN = 200 GeV Phys. Rev. C 105, 024901 (2022). Using these coefficients for three sets of two-particle correlations, azimuthal anisotropy coefficients v2 and v3 are extracted for midrapidity charged hadrons as a function of transverse momentum. In this paper, we use the available coefficients to explore various nonflow hypotheses as well as to compare the results with theoretical model calculations. The nonflow methods fail basic closure tests with ampt and pythia/angantyr, particularly when including correlations with particles in the low multiplicity light-projectile going direction. In data, the nonflow adjusted v2 results are modestly lower in p+Au and the adjusted v3 results are more significantly higher in p+Au and d+Au. However, the resulting higher values for the ratio v3/v2 in p+Au at RHIC compared to p+Pb at the LHC is additional evidence for a significant overcorrection. Incorporating these additional checks, the conclusion that these flow coefficients are dominated by initial geometry coupled with final-state interactions (e.g., hydrodynamic expansion of quark-gluon plasma) remains true, and explanations based solely on initial-state glasma are ruled out. The detailed balance between intrinsic and fluctuation-driven geometry and the exact role of weakly versus strongly coupled prehydrodynamic evolution remains an open question for triangular flow, requiring further theoretical and experimental investigation.
Experimental measurements in relativistic collisions of small systems from $p + p$ to $p/d/ ^3He + A$ at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) reveal particle ...emission patterns that are strikingly similar to those observed in $A + A$ collisions of large nuclei. One explanation of these patterns is the formation of small droplets of quark-gluon plasma (QGP) followed by hydrodynamic evolution. A geometry engineering program was proposed to further investigate these emission patterns, and the experimental data from that program in $p + Au, d + Au, ^3 He + Au$ collisions for elliptic and triangular anisotropy coefficients $v_2$ and $v_3$ follow the pattern predicted by hydrodynamic calculations C. Aidala et al. (PHENIX Collaboration), Nat. Phys. 15, 214 (2019). One alternative approach, referred to as initial-state correlations, suggests that for small systems the patterns observed in the final-state hadrons are encoded at the earliest moments of the collision and therefore require no final-state parton scattering or hydrodynamic evolution. Recently, new calculations using only initial-state correlations, in the dilute-dense approximation of gluon saturation physics, reported striking agreement with the $v_2$ patterns observed in $p/d/ ^3He + Au$ data at RHIC M. Mace, V. V. Skokov, P. Tribedy, and R. Venugopalan, Phys. Rev. Lett. 121, 052301 (2018). The results reported by Mace, Skokov, Tribedy and Venugopalan (MSTV) are counterintuitive and thus we aim here to reproduce some of the basic features of these calculations. In this first investigation, we provide a description of our publicly available model, ip-jazma, and investigate its implications for saturation scales, multiplicity distributions, and eccentricities, reserving for later work the analysis of momentum spectra and azimuthal anisotropies. We find that our implementation of the saturation physics model reproduces the results of the MSTV calculation of the multiplicity distribution in $d + Au$ collisions at RHIC. However, additional aspects of studies, together with existing data, call into question some of the essential elements reported by MSTV. Resolution of these issues will require further developments of ip-jazma, in order to determine if it can replicate the qualitative agreement with the $v_2$ reported by MSTV. Both the work reported here and future studies will establish which features in the experimental data are uniquely attributable to the color glass condensate description.
Does the charm flow at RHIC? Batsouli, S.; Kelly, S.; Gyulassy, M. ...
Physics letters. B,
03/2003, Letnik:
557, Številka:
1-2
Journal Article
Recenzirano
Odprti dostop
Recent PHENIX Au+Au→e−+X data Phys. Rev. Lett. 88 (2002) 192303 from open charm decay are shown to be consistent with two extreme opposite dynamical scenarios of ultra-relativistic nuclear reactions. ...Perturbative QCD without final state interactions was previously shown to be consistent with the data. However, we show that the data are also consistent with zero mean free path hydrodynamics characterized by a common transverse flow velocity field. The surprising coincidence of both D and B hydrodynamic flow spectra with pQCD up to pT≈3 and 5 GeV, respectively, suggests that heavy quarks may be produced essentially at rest in the rapidly expanding gluon plasma. Possible implications and further tests of collective heavy quark dynamics are discussed.
Therapeutic intervention for atherosclerosis has predominantly concentrated on regulating cholesterol levels; however, these therapeutics are not efficacious for all patients, suggesting that other ...factors are involved. This study was initiated to identify mechanisms that regulate atherosclerosis predisposition in mice other than cholesterol level regulation. To do so we performed quantitative trait locus analysis using two inbred strains that each carry the atherosclerosis phenotype-sensitizing Apoe deficiency and that have been shown to have widely disparate predilection to atherosclerotic lesion formation. One highly significant locus on chromosome 10 (LOD = 7.8) accounted for 19% of the variance in lesion area independent of cholesterol. Two additional suggestive loci were identified on chromosomes 14 (LOD = 3.2) and 19 (LOD = 3.2), each accounting for 7-8% of the lesion variance. In all, five statistically significant and suggestive loci affecting lesion size but not lipoprotein levels were identified. Many of these were recapitulated in an independent confirmatory cross. In summary, two independently performed crosses between C57BL/6 and FVB/N Apoe-deficient mice have revealed several previously unreported atherosclerosis susceptibility loci that are distinct from loci linked to lipoprotein levels.
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