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arXiv 1502.00230nucl-ex
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在$\sqrt{s}$ =0.9、2.76和7 TeV时pp碰撞中的前向-后向多重数相关

Forward-backward multiplicity correlations in pp collisions at $\sqrt{s}$=0.9, 2.76 and 7 TeV

ALICE Collaboration

摘要:

用ALICE探测器测量了质子-质子(pp)碰撞中$\sqrt{s}=0.9$、2.76和7 TeV的前向-后向多重关联强度。测量是在中心赝快度区($|η| < 0.8$)进行的横向动量$p_{\rm T}>0.3$ GeV/ $c$。在$η=0$周围对称地选择两个宽度为0.2至0.8的单独的伪快度窗口($δη$)。多重关联强度($b_{\rm cor}$)作为两个窗口之间的赝快度间隙($η_{\rm gap}$)以及这些窗口的宽度的函数进行了研究。发现相关强度随着$η_{\rm gap}$的增加而减小,并且显示出与$δη$的非线性增加。一个相当大的增加的相关强度与碰撞能量,这不能完全解释的窗口内的平均多重性的增加,观察。还测量了在对称FB $η$窗口内选择的两个方位角扇区的不同配置中的多重性的相关系数。观察到两种不同的贡献,短程(SR)和长程(LR)。$b_{\rm cor}$的能量依赖性被发现是弱的SR组件,而它是强的LR组件。此外,相关系数的粒子属于不同的横向动量间隔选择具有相同的平均多重性进行了研究。在这种情况下,发现SR和LR对$b_{\rm cor}$的贡献都随着$p_{\rm T}$的增加而增加。结果进行比较PYTHIA和PHOJET事件发生器和字符串为基础的唯象模型。观察到的$b_{\rm cor}$的依赖性增加了新的约束现象学模型。

英文摘要:

The strength of forward-backward (FB) multiplicity correlations is measured by the ALICE detector in proton-proton (pp) collisions at $\sqrt{s}=0.9$, 2.76 and 7 TeV. The measurement is performed in the central pseudorapidity region ($|η| < 0.8$) for the transverse momentum $p_{\rm T}>0.3$ GeV/$c$. Two separate pseudorapidity windows of width ($δη$) ranging from 0.2 to 0.8 are chosen symmetrically around $η=0$. The multiplicity correlation strength ($b_{\rm cor}$) is studied as a function of the pseudorapidity gap ($η_{\rm gap}$) between the two windows as well as the width of these windows. The correlation strength is found to decrease with increasing $η_{\rm gap}$ and shows a non-linear increase with $δη$. A sizable increase of the correlation strength with the collision energy, which cannot be explained exclusively by the increase of the mean multiplicity inside the windows, is observed. The correlation coefficient is also measured for multiplicities in different configurations of two azimuthal sectors selected within the symmetric FB $η$-windows. Two different contributions, the short-range (SR) and the long-range (LR), are observed. The energy dependence of $b_{\rm cor}$ is found to be weak for the SR component while it is strong for the LR component. Moreover, the correlation coefficient is studied for particles belonging to various transverse momentum intervals chosen to have the same mean multiplicity. Both SR and LR contributions to $b_{\rm cor}$ are found to increase with $p_{\rm T}$ in this case. Results are compared to PYTHIA and PHOJET event generators and to a string-based phenomenological model. The observed dependencies of $b_{\rm cor}$ add new constraints on phenomenological models.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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