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arXiv 0903.2165nucl-thhep-phnucl-ex
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根据多相输运模型计算的双强子方位角关联的反应面角依赖性

Reaction plane angle dependence of dihadron azimuthal correlations from a multiphase transport model calculation

W. Li, S. Zhang, Y. G. Ma, X. Z. Cai, J. H. Chen, H. Z. Huang, G. L. Ma, C. Zhong

摘要:

用多相输运模型(AMPT)研究了$\sqrt{s_{NN}}$ = 200 GeV的Au + Au碰撞中相对于反应面的双强子方位角关联.这种与反应面方位角相关的关联可以揭示高横动量粒子在热稠密介质中传播的能量损失的路径长度效应。相关性随触发粒子相对于反应平面方向的方位角$ϕ_{s}=ϕ_{T}-Ψ_{EP}$而变化,这与STAR合作的实验观察一致。当触发粒子的方向从反应平面的面内到面外时,触发粒子远离侧的双强子方位角关联函数呈现出明显的由单峰到宽峰(可能是双峰)的演化.在$ϕ_{s}$的某些区域,远离侧的角关联函数相对于背对背方向是不对称的,这可以为测试$v_{1}$方法重建反应面提供见解。此外,背侧关联分布的均方根宽度($W_{rms}$)和背侧双峰间的分裂参数$D$都随$ϕ_{s}$的增加而略有增加,背侧关联强子的平均横动量表现出强烈的$ϕ_{s}$依赖性.我们的结果表明,强的部分子级联和由此产生的能量损失对触发粒子远侧双强子方位角关联函数出现双峰结构起着重要作用.

英文摘要:

Dihadron azimuthal angle correlations relative to the reaction plane have been investigated in Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV using a multi-phase transport model (AMPT). Such reaction plane azimuthal angle dependent correlations can shed light on path-length effect of energy loss of high transverse momentum particles propagating through the hot dense medium. The correlations vary with the trigger particle azimuthal angle with respect to the reaction plane direction, $ϕ_{s}=ϕ_{T}-Ψ_{EP}$, which is consistent with the experimental observation by the STAR collaboration. The dihadron azimuthal angle correlation functions on the away side of the trigger particle present a distinct evolution from a single peak to a broad, possibly double peak, structure when the trigger particle direction goes from in-plane to out-of-plane of the reaction plane. The away-side angular correlation functions are asymmetric with respect to the back-to-back direction in some regions of $ϕ_{s}$, which could provide insight on testing $v_{1}$ method to reconstruct the reaction plane. In addition, both the root-mean-square width ($W_{rms}$) of the away-side correlation distribution and the splitting parameter $D$ between the away-side double peaks increase slightly with $ϕ_{s}$, and the average transverse momentum of the away-side associated hadrons shows a strong $ϕ_{s}$ dependence. Our results indicate that strong parton cascade and resultant energy loss could play an important role for the appearance of a double-peak structure in the dihadron azimuthal angular correlation function on the away side of the trigger particle.

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