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arXiv 1102.0931nucl-exhep-ex
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STAR中前向快度下的两粒子方位角关联

Two-particle azimuthal correlations at forward rapidity in STAR

Ermes Braidot

摘要:

在2008年的运行中,位于纽约布鲁克海文国家实验室(BNL)的相对论重离子对撞机(RHIC)在$\sqrt{s_{NN}}=200\mathrm{\,GeV}$的p+p和d+Au碰撞中都提供了高亮度。电磁量热计在STAR中的接受度通过新的前向介子谱仪(FMS)得到了提高,现在几乎与$-1<η\4$在整个方位角上是连续的。这使得测量的方位角之间的相关性的一个向前中性π介子和第二个粒子在一个非常大的快度范围。双强子方位角关联提供了对核靶中胶子密度的低纵向动量分数($x$)分量的灵敏度。初始状态的非线性效应,实际上预计将出现在d+金碰撞时,密集的部分的核探测。本文的分析表明,这种关联及其对快度、横动量和碰撞中心性的依赖性与相对论核中胶子饱和效应的存在是定性一致的。理论预期的方位角之间的相关性稀释系统(氘)和饱和的目标(金核)进行了探索。

英文摘要:

During the 2008 run the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven Nation Laboratiory (BNL), NY, provided high luminosity in both p+p and d+Au collisions at $\sqrt{s_{NN}}=200\mathrm{\,GeV}$. Electromagnetic calorimeter acceptance in STAR was enhanced by the new Forward Meson Spectrometer (FMS), and is now almost contiguous from $-1<η\4$ over the full azimuth. This allows measurements of the azimuthal correlation between a forward neutral pion and a second particle in a very large rapidity range. Di-hadron azimuthal correlations provide sensitivity to the low longitudinal momentum fraction ($x$) component of the gluon density in the nuclear target. Initial state nonlinear effects are in fact expected to appear in d+Au collisions when the dense part of the nucleus is probed. The analysis in this thesis shows that such correlations and their dependence on rapidity, transverse momentum and collision centrality are qualitative consistent with the existence of gluon saturation effects in the relativistic nucleus. Theoretical expectations for azimuthal correlations between a dilute system (deuteron) and a saturated target (Gold nucleus) have been explored.

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