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Wu Yuanfang

Publications and source records attributed to Wu Yuanfang.

12 recordsLinked to original sources
arXiv2013

Finite-size behavior near the critical point of QCD phase-transition

It is pointed out that finite-size effect is not negligible in locating critical point of QCD phase transition at current relativistic heavy ion collisions. Finite-size behavior near critical point, in particular, finite-size scaling and fixed-point behavior of the final observables can be served as a quantitative identification of critical point and the nearby boundary of the QCD phase transition. The validity of the method at finite detector acceptances at RHIC is discussed.

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arXiv2012

Eccentricity and elliptic flow at fixed centrality in Au+Au collisions at sqrt(s_NN)=200GeV in AMPT

To reduce the effect of the fluctuations of initial geometrical shape, elliptic flow are studied at fixed centrality in Au+Au collision at $\sqrt{s_{\rm NN}}$=200GeV. It is observed with the participant increasing, elliptic flow has an increase and a decrease at different fixed impact parameter, but not a trivial fluctuation. It is analyzed that the initial space anisotropy dominates the participant dependence of elliptic flow in near-central collisions(b=5fm) and mid-central collisions(b=8fm), while the interaction between particles can mainly answer for the behavior of elliptic flow in peripheral collisions(b=12fm). To distinguish the pure geometrical effect, elliptic flow scaled by initial eccentricity is studied. It is found that the ratio $v_{2}/ε$ increases with participant and reaches a saturation when the participant is large enough, indicating that the collision system reach the local equilibrium.

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arXiv2011

Statistical and dynamical fluctuations in the ratios of higher cumulants in relativistic heavy ion collisions

With the help of transport and statistical models, we find that the ratios of higher net-proton cumulants measured at RHIC are dominated by the statistical fluctuations. Future measurements should focus on the dynamical fluctuations, which are relevant to the underlying mechanisms of particle production, the critical phenomena in particular. We also demonstrate that a proton-antiproton correlation directly show if protons and antiprotons are emitted independently.

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arXiv2009

Locating critical point of QCD phase transition basing on finite-size scaling

It is argued that in relativistic heavy ion collisions, due to limited size of the formed matter, the reliable criterion of critical point is finite-size scaling, rather than non-monotonous behavior of observable. How to locate critical point by finite-size scaling is proposed. The data of $\pt$ correlation from RHIC/STAR are analyzed. Critical points are likely observed around $\sqrt s =62$ and 200 GeV. They could be, respectively, the transition of deconfinement and chiral symmetry restoration predicted by lattice-QCD. Further confirmation with other observable and energies is suggested.

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arXiv2008

Is there hydrodynamic flow at RHIC ?

It is argued that the observation of anisotropic azimuthal distribution of final state particles alone is insufficient to show whether the formed matter at RHIC behaves like hydrodynamic flow. Examining the intrinsic interaction (or correlation) of the formed matter should provide more definite judgement. To the end, a spatial-dependent azimuthal multiplicity-correlation pattern is suggested. It shows clearly in the pattern that there are two kinds of interactions at the early stage of Au + Au collisions at $\sqnn=200$ GeV generated by RQMD with hadron re-scattering and AMPT with string melting. This is out of the expectation from the elliptic flow driven by anisotropic expansion.

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arXiv2004

Charge Fluctuations in $π^{+}\rp$ and $\rK^{+}\rp$ Collisions at 250 GeV/$c$

We report on measurements of event-by-event charge fluctuations in $π^{+}\rp$ and $\rK^{+}\rp$ collisions at 250 GeV/$c$. The dependence of these fluctuations on the size of the rapidity windows are presented for the first time in the full phase space domain. The corrections for the influence of global charge conservation and leading-particle stopping are tested by the data. The discrepancy due to incomplete correction given by STAR and PHENIX are estimated. The dependence of the fluctuations on the position of the rapidity bin and on the multiplicity at different rapidity windows are also presented.

hep-ex↗
arXiv2002

On the Stability of Rapidity Gap Analysis

It is argued that the newly introduced moments of rapidity gaps for the event-by-event fluctuations depends on the number of events and multiplicity. The interesting ones of them are unstable under ISR energies of h-h collisions. The instability get well improved when multiplicity increases.

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arXiv1999

The Influence of Statistical Fluctuations on Erraticity Behavior of Multiparticle System

It is demonstrated that in low multiplicity sample, the increase of the fluctuation of event-factorial-moments with the diminishing of phase space scale, called ``erraticity'', are dominated by the statistical fluctuations. The erraticity behavior observed at NA27 experiment can be readily reproduced by pure statistical fluctuations. Applying erraticity analysis to a high multiplicity sample is recommended and the method is improved at very high multiplicity case as well.

hep-ph↗
arXiv1999

On the Dominance of Statistical Fluctuation in the Factorial-Moment Study of Chaos in Low Multiplicity Events of High Energy Collisions

It is shown using Monte Carlo simulation that for low multiplicity events the single-event factorial moments are saturated by the statistical fluctuations. The diverse of the event-space moments $C_{p,q}$ of single-event moments with the diminishing of phase space scale, called ``erraticity'', observed in experiment can readily be reproduced by a flat probability distribution with only statistical fluctuations and therefore does not indicate the existence of chaos as suggested. The possibility of studying chaos in high multiplicity events using erraticity analysis is discussed.

hep-ph↗
arXiv1998

Scaling Exponent and Fluctuation Strength in High Energy Collisions

The information on dynamical fluctuations that can be extracted from the anomalous scaling observed recently in hadron-hadron collision experiments is discussed in some detail. A parameter ``effective fluctuation strength'' is proposed to estimate the strength of dynamical fluctuations. The method for extracting its value from the experimentally observed quantities is given. Some examples for the application of this method to real experimental data are presented.

hep-ph↗
arXiv1996

Source Function Determined from HBT Correlations by the Maximum Entropy Principle

We study the reconstruction of the source function in space-time directly from the measured HBT correlation function using the Maximum Entropy Principle. We find that the problem is ill-defined without at least one additional theoretical constraint as input. Using the requirement of a finite source lifetime for the latter we find a new Gaussian parametrization of the source function directly in terms of the measured HBT radius parameters and its lifetime, where the latter is a free parameter which is not directly measurable by HBT. We discuss the implications of our results for the remaining freedom in building source models consistent with a given set of measured HBT radius parameters.

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