论文标题
净能量依赖性的净$λ$波动通过rhic的星级实验测量
Beam energy dependence of net-$Λ$ fluctuations measured by the STAR experiment at RHIC
论文作者
论文摘要
粒子多重性分布的测量值对了解量子染色体动力学(QCD)强调状态中保守量子数的波动产生了巨大的兴趣,尤其是在可能的临界点附近和化学冻结附近。我们报告了校正累积比的效率和中心量宽度的测量($ c_ {2}/c_ {1} $,$ c_ {3}/c_ {3}/c_ {2} $的net- $λ$分布,在陌生和巴里元数的背景下,碰撞能量和快速的函数,在陌生和巴里元的情况下,均具有陌生和巴里元数的环境。结果适用于五个梁能量($ \ sqrt {s_ {nn}} $ = 19.6、27、39、62.4和200 GEV)的AU + AU碰撞($ \ sqrt {s_ {nn}} $ = 19.6、27、39、62.4和200 GEV)在RHIC(Star)的螺线管跟踪器中记录。我们将结果与泊松和负二项式(NBD)的期望以及超相关量子分子动力学(URQMD)和强子共振气(HRG)模型预测进行比较。 NBD和Poisson基准都与统计和系统不确定性中的数据一致。测得的累积物的比率没有临界波动的特征。从最近的HRG计算中提取的化学冷冻温度,该温度成功地用来描述净蛋白,净 - 荷兰和净收税数据,表明$λ$冻结条件与Kaons类似。但是,与从净普罗顿波动获得的温度相比,发现很大的偏差。净$λ$累积物显示出弱但有限的依赖对检测器的速度覆盖率的依赖性,这可以归因于量子数量保存。
The measurements of particle multiplicity distributions have generated considerable interest in understanding the fluctuations of conserved quantum numbers in the Quantum Chromodynamics (QCD) hadronization regime, in particular near a possible critical point and near the chemical freeze-out. We report the measurement of efficiency and centrality bin width corrected cumulant ratios ($C_{2}/C_{1}$, $C_{3}/C_{2}$) of net-$Λ$ distributions, in the context of both strangeness and baryon number conservation, as a function of collision energy, centrality and rapidity. The results are for Au + Au collisions at five beam energies ($\sqrt{s_{NN}}$ = 19.6, 27, 39, 62.4 and 200 GeV) recorded with the Solenoidal Tracker at RHIC (STAR). We compare our results to the Poisson and negative binomial (NBD) expectations, as well as to Ultra-relativistic Quantum Molecular Dynamics (UrQMD) and Hadron Resonance Gas (HRG) model predictions. Both NBD and Poisson baselines agree with data within the statistical and systematic uncertainties. The ratios of the measured cumulants show no features of critical fluctuations. The chemical freeze-out temperatures extracted from a recent HRG calculation, which was successfully used to describe the net-proton, net-kaon and net-charge data, indicate $Λ$ freeze-out conditions similar to those of kaons. However, large deviations are found when comparing to temperatures obtained from net-proton fluctuations. The net-$Λ$ cumulants show a weak, but finite, dependence on the rapidity coverage in the acceptance of the detector, which can be attributed to quantum number conservation.