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arXiv 1212.2001nucl-exhep-ex
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$\sqrt{s_{\rm NN}}$ = 5.02 TeV p-Pb碰撞中近端和远端的长程角关联

Long-range angular correlations on the near and away side in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV

ALICE Collaboration

摘要:

利用ALICE探测器测量了核子-核子质心能量为5.02 TeV的p-Pb碰撞中,在0.5 < $p_{\rm T}^{\rm assoc}$ < $p_{\rm T}^{\rm trig}$ < 4 GeV/ $c$的横动量范围内,带电触发粒子和伴随粒子之间的角关联.在两个单位的赝快度和全方位角在不同的事件多重性的时间间隔内测量的相关性,并表示为每个触发粒子的关联产额。两个远程脊状结构,一个在近侧和一个在远侧,观察到当每个触发产量在低多重性事件中获得的减去从一个在高多重性事件。近侧的过量在质量上与CMS协作最近报告的类似,而远侧的过量是第一次报告。投影到方位角上的双脊结构用第二和第三傅立叶系数以及近侧和远侧产率和宽度来量化。在所有研究的事件多重性和$p_{\rm T}$箱的不确定性范围内,近端和远端的产额相等,并且宽度没有显示出随事件多重性或$p_{\rm T}$的显著演化。这些发现表明,近侧脊是伴随着一个基本相同的远离侧脊。

英文摘要:

Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for transverse momentum ranges within 0.5 < $p_{\rm T}^{\rm assoc}$ < $p_{\rm T}^{\rm trig}$ < 4 GeV/$c$. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and $p_{\rm T}$ bins, and the widths show no significant evolution with event multiplicity or $p_{\rm T}$. These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge.

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