Fluctuations In Au Research Articles

Excitation Function of Net Charge Fluctuations at RHIC

We present measurements of net charge and transverse momentum fluctuations in Au + Au collisions at ?sNN = 20, 130, and 200 GeV reported in our QM 2004 poster using measures ?+-,dyn and <?pt,1 ?pt,2>. We observe the dynamical fluctuations are finite at all three energies and exhibit a rather modest dependence on beam energy. We also find both net charge and pt fluctuations violate the trivial 1/N scaling expected for nuclear collisions consisting of independent nucleon-nucleon interactions. We speculate the observed centrality dependence arises due to radial flow and might provide insight on the width and shape of the radial flow profile.

Possible resolutions of theD-puzzle

We explore possible ways of explaining the net charge event-by-event fluctuations in Au+Au collisions observed in experiments at the Relativistic Heavy Ion Collider within a quark recombination model. We estimate the number of quarks at recombination and their implications for the predicted net charge fluctuations. We also discuss the consequences of diquark and quark-antiquark clustering above the deconfinement temperature.

Charged particle multiplicity fluctuations in Au + Au collisions at

This paper presents the first PHOBOS results on charged particle multiplicity fluctuations measured for Au+Au collisions at the highest RHIC energy within a wide pseudorapidity range of |η| < 3. The dependence on collision geometry is removed in the analysis by using the normalized difference between the number of particles in separate η bins. We compare our data to HIJING model predictions.

Jet quenching and event-wise mean-pt fluctuations in central Au–Au collisions at [formula omitted] GeV in Hijing-1.37

Based on Hijing-1.37 simulations, event-wise mean-pt fluctuations in Au–Au collisions at sNN=200 GeV are studied with graphical and numerical methods. This study shows that jets/minijets could represent a substantial source of mean-pt fluctuations, and jet quenching could reduce these fluctuations significantly. Mean-pt fluctuation measurements are a promising probe of correlation structure produced in the early stages of central Au–Au collisions at RHIC energies.

Charge fluctuations in Au+Au collisions at RHIC energy

A hadron and string cascade model, JPCIAE, together with the corresponding Monte Carlo event generator, has been employed in this paper to investigate further the charge fluctuations in Au+Au collisions at √ s nn = 130 GeV. The default JPCIAE calculations are in good agreement with PHENIX and STAR data. We found that the thermal predictions for the π gas, the resonance π gas and quark matter deviate, respectively. from the corresponding dynamical simulations from the JPCIAE model. The discrepancies were also found between the π charge fluctuations and the charge fluctuations of all species of hadrons. However the charge fluctuations for “π from ρ and ω decay” and for all the hadrons from resonance decay are close to each other, indicating the correlation between positively and negatively charged hardrons is not sensitive to the species of hardrons. This work shows further that it is questionable to use the charge fluctuations as a signature of QGP.

Scaling of solar wind ϵ and the AU, AL and AE indices as seen by WIND

We apply the finite size scaling technique to quantify the statistical properties of fluctuations in AU, AL and AE indices and in the ϵ parameter that represents energy input from the solar wind into the magnetosphere. We find that the exponents needed to rescale the probability density functions (PDF) of the fluctuations are the same to within experimental error for all four quantities. This self‐similarity persists for time scales up to ∼4 hours for AU, AL and ϵ and up to ∼2 hours for AE. Fluctuations on shorter time scales than these are found to have similar long‐tailed (leptokurtic) PDF, consistent with an underlying turbulent process. These quantitative and model‐independent results place important constraints on models for the coupled solar wind‐magnetosphere system.