arXiv subjects

Xiao-Mei Li

Publications and source records attributed to Xiao-Mei Li.

24 records · Page 2Linked to original sources

arXiv2009

Reexamination for the calculation of elliptic flow and other fourier harmonics

We have argued that the azimuthal symmetry and asymmetry components in fourier expansion of particle momentum azimuthal distribution, $v_n$ (n=0, 1, 2, ...), should be calculated as an average of $cos(nϕ)$ first over particles in an event and then over events (event-wise average) rather than "an average over all particles in all events" (particle-wise average). In case of large centrality (multiplicity) bin the particle-wise average is not accurate because the influence (fluctuation) of particle multiplicity was not taken into account.

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arXiv2009

Centrality bin size dependence of multiplicity correlation in central Au+Au collisions at $\sqrt{s_NN}$=200 GeV}

We have studied the centrality bin size dependence of charged particle forward-backward multiplicity correlation strength in 5%, 0-5%, and 0-10% most central Au+Au collisions at $\sqrt{s_NN}}$=200 GeV with a parton and hadron cascade model, PACIAE based on PYTHIA. The real (total), statistical, and NBD (Negative Binomial Distribution) correlation strengths are calculated by the real events, the mixed events, and fitting the charged particle multiplicity distribution to the NBD, respectively. It is turned out that the correlation strength increases with increasing centrality bin size monotonously. If the discrepancy between real (total) and statistical correlation strengths is identified as dynamical one, the dynamical correlation may just be a few percent of the total (real) correlation.

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arXiv2009

Exploring behaviors of partonic matter forming in early stage of $pp$ and nucleus-nucleus collisions at ultra-relativistic energies

The parton yield, (pseudo)rapidity distribution, and transverse momentum distribution in partonic matter assumed forming in the early stage of $pp$ and nucleus-nucleus collisions at RHIC energy ($\sqrt{s_{NN}}$=200 GeV) and LHC energy ($\sqrt{s_{NN}}$=5.5 TeV for nucleus-nucleus, 5.5 and/or 14 TeV for $pp$) are comparatively investigated with parton and hadron cascade model PACIAE. It turned out that the different parton and anti-parton spectra approach to be similar with reaction energy increasing from RHIC to LHC. We have argued that if the partonic matter forming in Au+Au collisions at RHIC energy is strongly interacting quark-gluon plasma, the one forming in Pb+Pb collisions at LHC energy might approach the real (free) quark-gluon plasma.

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arXiv2008

PACIAE Model Predictions for Pb+Pb Collisions at LHC Compared to the Au+Au Collisions at RHIC

The parton and hadron cascade model PACIAE is used to simulate the 0-6, 15-25, and 35-45 % most central Au+Au collisions at \sqrt{s_{NN}}=19.6, 62.4, 130, and 200 GeV and the 0-10 % most central Pb+Pb collisions at \sqrt{s_{NN}}=5500 GeV. The calculated charged multiplicity and the charged particle transverse momentum distribution, pseudorapidity distribution, and extended longitudinal scaling for Au+Au collisions well agree with the corresponding PHOBOS data. Thus the above observables calculated for Pb+Pb collisions would be a reliable prediction.

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arXiv2008

Theoretical analysis for the apparent discrepancy between pbarp and pp data in charged particle forward-backward multiplicity correlations

The strength of charged particle forward-backward multiplicity correlation in pbar+p and p+p collisions at s^1/2 = 200 GeV is studied by PYTHIA 6.4 and compared to the UA5 and STAR data correspondingly. It is turned out that a factor of 3-4 apparent discrepancy between UA5 and STAR data can be attributed to the differences in detector acceptances and observing bin interval in both experiments. A mixed event method is introduced and used to calculate the statistical correlation strength and the dynamical correlation strengths stemming from the charge conservation, four- momentum conservation, and decay, respectively. It seems that the statistical correlation is much larger than dynamical one and the charge conservation, four-momentum conservation and decay may account for most part of the dynamical correlation. In addition, we have also calculated the correlation strength by fitting the charged particle multiplicity distribution from PYTHIA to the Negative Binomial Distribution and found that the result agrees well with the correlation strength calculated by mixed events.

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arXiv2006

Discrepancy between hadron matter and quark-gluon matter in net charge transfer fluctuation

A parton and hadron cascade model, PACIAE, is employed to investigate the net charge transfer fluctuation within $|η|$=1 in Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV. It is turned out that the observable of net charge transfer fluctuation, $κ$, in hadronic final state (HM) is nearly a factor of 3 to 5 larger than that in initial partonic state (QGM). However, only twenty percent of the net charge transfer fluctuation in the QGM can survive the hadronization

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