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arXiv 1802.09145nucl-exhep-ex
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在LHC上pp,p-Pb和Pb-Pb碰撞中带电粒子的横动量谱和核修正因子

Transverse momentum spectra and nuclear modification factors of charged particles in pp, p-Pb and Pb-Pb collisions at the LHC

ALICE Collaboration

摘要:

本文报道了在$0.15<p_{\rm T}<50$ GeV/$p_{\rm T}$和$|η|< 0.8$的运动学范围内,质心能量为$\sqrt{s_{\rm NN}} = 5.02$ TeV的pp、p-Pb和Pb-Pb碰撞中初级带电粒子的测量横动量谱.一个显着的改善系统的不确定性的动机在pp和Pb-Pb碰撞在$\sqrt{s_{\rm NN}} = 2.76$ TeV的数据重新分析,以及在p-Pb碰撞在$\sqrt{s_{\rm NN}} = 5.02$ TeV,这也是提出。从铅铅碰撞的光谱在9个中心的间隔,并进行了比较,从PP碰撞的参考谱标度的二元核子-核子碰撞的数量。对于中心碰撞,$p_{\rm T}$谱在6-7 GeV/ $c$附近被抑制超过7倍,并且在高达30 GeV/ $c$的更高动量处抑制显著减小。核修正因子$R_{\rm pPb}$,由在相同碰撞能量下测得的pp和p-Pb能谱构造而成,在8 GeV/ $c$以上与1一致。虽然在pp和Pb-Pb碰撞的光谱是实质上更难在$\sqrt{s_{\rm NN}} = 5.02$ TeV相比,2.76 TeV,核修改因子显示没有显着的碰撞能量依赖性。所得到的结果应提供进一步的约束部分子能量损失的计算,以确定热的和致密的QCD物质的输运性质。

英文摘要:

We report the measured transverse momentum ($p_{\rm T}$) spectra of primary charged particles from pp, p-Pb and Pb-Pb collisions at a center-of-mass energy $\sqrt{s_{\rm NN}} = 5.02$ TeV in the kinematic range of $0.15<p_{\rm T}<50$ GeV/$c$ and $|η|< 0.8$. A significant improvement of systematic uncertainties motivated the reanalysis of data in pp and Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV, as well as in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV, which is also presented. Spectra from Pb-Pb collisions are presented in nine centrality intervals and are compared to a reference spectrum from pp collisions scaled by the number of binary nucleon-nucleon collisions. For central collisions, the $p_{\rm T}$ spectra are suppressed by more than a factor of 7 around 6-7 GeV/$c$ with a significant reduction in suppression towards higher momenta up to 30 GeV/$c$. The nuclear modification factor $R_{\rm pPb}$, constructed from the pp and p-Pb spectra measured at the same collision energy, is consistent with unity above 8 GeV/$c$. While the spectra in both pp and Pb-Pb collisions are substantially harder at $\sqrt{s_{\rm NN}} = 5.02$ TeV compared to 2.76 TeV, the nuclear modification factors show no significant collision energy dependence. The obtained results should provide further constraints on the parton energy loss calculations to determine the transport properties of the hot and dense QCD matter.

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