R. L. Ray

Applicability of Monte Carlo Glauber models to relativistic heavy-ion collision data

The accuracy of Monte Carlo Glauber model descriptions of minimum-bias multiplicity frequency distributions is evaluated using data from the Relativistic Heavy Ion Collider (RHIC) within the context of a sensitive, power-law representation introduced previously by Trainor and Prindle (TP). Uncertainties in the Glauber model input and in the midrapidity multiplicity frequency distribution data are reviewed and estimated using the TP centrality methodology. The resulting errors in model-dependent geometrical quantities used to characterize heavy-ion collisions (i.e. impact parameter, number of nucleon participants Npart, number of binary interactions Nbin and average number of binary collisions per incident participant nucleon ?) are presented for minimum-bias Au?Au collisions at = 20, 62, 130 and 200 GeV and Cu?Cu collisions at = 62 and 200 GeV. Considerable improvement in the accuracy of collision geometry quantities is obtained compared to previous Monte Carlo Glauber model studies, confirming the TP conclusions. The present analysis provides a comprehensive list of the sources of uncertainty and the resulting errors in the above geometrical collision quantities as functions of centrality. The capability of energy deposition data from trigger detectors to enable further improvements in the accuracy of collision geometry quantities is also discussed.

Challenging the utility of third-order azimuth harmonics in the description of ultrarelativistic heavy-ion collisions

In recent years it has become conventional practice to include higher-order cylindrical harmonics in the phenomenological description of two-particle angular correlations from ultra-relativistic heavy-ion collisions. These model elements, whose dependence on relative azimuth angle has the form

Gluon correlations from a glasma flux-tube model compared to measured hadron correlations on transverse momentum (pt,pt) and angular differences (ηΔ,φΔ)

\cos[m(\phi_1-\phi_2)]

Statistical-noise reduction in correlation analysis of high-energy nuclear collisions with event-mixing

where

Challenging claims of nonjet “higher harmonic” components in 2D angular correlations from high-energy heavy-ion collisions

m > 2

Challenging claims of ?elliptic flow? by comparing azimuth quadrupole and jet-related angular correlations from Au?Au collisions at

, were introduced to support a hydrodynamic flow interpretation of the same-side (

\sqrt{{{s}_{NN}}}

|\phi_1-\phi_2| 2

= 62 and 200 GeV

harmonics are not required by the data, that they destabilize the fitting models, and that their net effect is to decompose the same-side peak into two components, one being dependent on and the other being independent of relative pseudorapidity. Thus we are lead to question whether descriptions of angular correlation data including higher-order harmonics inform our understanding of the same-side peak or heavy-ion collisions in general. Results from analysis of two-dimensional angular correlation data from the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC) show that the RHIC data do not exclude a single-Gaussian hypothesis for the same-side peak. We find that the net effect of including the

Can doubly strange dibaryon resonances be discovered at RHIC

m = 3

Two-body Bose-Einstein correlations in simulated relativistic heavy ion collision events

harmonic or azimuth sextupole in the fitting model is the inclusion of small non-Gaussian dependence in the mathematical description of the same-side peak. Those non-Gaussian effects are systematically insignificant and can be accommodated by minor perturbations to the same-side 2D Gaussian peak model, which act locally at small relative azimuth. We also demonstrate that the 0-1% 2D angular correlation data for 2.76 TeV Pb+Pb collisions from ATLAS, which display an away-side double peak on azimuth, do not require a sextupole and exclude a positive same-side sextupole.