Poisson baseline of net-charge fluctuations in relativistic heavy ion collisions

Taking doubly charged particles,positive-negative charge pair production and the effects of volume fluctuations into account,the Poisson baseline of the fluctuations of net-charge is studied.Within the Poisson baseline,the cumulants of net-charge are derived.Comparing to the Skellam baseline of net-charge,we infer that doubly charged particles broaden the distributions of net-charge,while positive-negative charge pairs narrow the distributions.Using the ratios of doubly charged particles and positive-negative charge pairs from neutral resonance decays to the total positive charges from THERMINATOR 2,the first four orders of moments and the corresponding moment products are calculated in the Poisson baseline for Au + Au collisions at (s_(NN))(1/2)= 200 GeV at RHIC/STAR.We find that the standard deviation is mainly influenced by the resonance decay,while the third and fourth order moments and corresponding moment products are mainly modified and fit the data of RHIC/STAR much better after including the effects of volume fluctuations.     

Investigation of experimental observables in search of the chiral magnetic effect in heavy-ion collisions in the STAR experiment

The chiral magnetic effect(CME)is a novel transport phenomenon,arising from the interplay between quantum anomalies and strong magnetic fields in chiral systems.In high-energy nuclear collisions,the CME may survive the expansion of the quark-gluon plasma fireball and be detected in experiments.Over the past two decades,experimental searches for the CME have attracted extensive interest at the Relativistic Heavy Ion Collider(RHIC)and the Large Hadron Collider(LHC).The main goal of this study is to investigate three pertinent experimental approaches:the$\gamma$correlator,the R correlator,and the signed balance functions.We exploit simple Monte Carlo simulations and a realistic event generator(EBE-AVFD)to verify the equivalence of the core components among these methods and to ascertain their sensitivities to the CME signal and the background contributions for the isobar collisions at the RHIC.