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arXiv 1503.00681nucl-exhep-ex
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在$\sqrt{s_\rm{NN}} = 5.02$ TeV上测量p-Pb碰撞中带电喷流产生截面和核修正

Measurement of charged jet production cross sections and nuclear modification in p-Pb collisions at $\sqrt{s_\rm{NN}} = 5.02$ TeV

ALICE Collaboration

摘要:

本文报道了在LHC上用ALICE探测器测量的$\sqrt{s_{\rm NN}} = 5.02$ TeV p-Pb碰撞中带电喷流产生截面。利用反$k_{\rm T}$算法,用分辨参数$R = 0.2$和$R = 0.4$重建了中心快度区的带电粒子喷流.重建的喷流已被校正的探测器的影响和潜在的事件背景。为了计算p-Pb碰撞中带电喷流的核修正因子$R_{\rm pPb}$,通过在$\sqrt{s} = 7$ TeV处缩放先前测量的带电喷流光谱来构造pp参考。在横向动量范围$20 \le p_{\rm T,ch\ jet} \le 120$ GeV/ $c$,$R_{\rm pPb}$被发现是一致的与统一,表明没有强烈的核物质对喷流产生的影响。通过两种不同分辨率参数重建的射流产生截面比,对径向射流结构进行了重大修改。这个比率被发现是类似于在$\sqrt{s} = 7$ TeV的PP碰撞的测量和从PYTHIA PP模拟和NLO pQCD计算在$\sqrt{s_{\rm NN}} = 5.02$ TeV的预期。

英文摘要:

Charged jet production cross sections in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV measured with the ALICE detector at the LHC are presented. Using the anti-$k_{\rm T}$ algorithm, jets have been reconstructed in the central rapidity region from charged particles with resolution parameters $R = 0.2$ and $R = 0.4$. The reconstructed jets have been corrected for detector effects and the underlying event background. To calculate the nuclear modification factor, $R_{\rm pPb}$, of charged jets in p-Pb collisions, a pp reference was constructed by scaling previously measured charged jet spectra at $\sqrt{s} = 7$ TeV. In the transverse momentum range $20 \le p_{\rm T,ch\ jet} \le 120$ GeV/$c$, $R_{\rm pPb}$ is found to be consistent with unity, indicating the absence of strong nuclear matter effects on jet production. Major modifications to the radial jet structure are probed via the ratio of jet production cross sections reconstructed with the two different resolution parameters. This ratio is found to be similar to the measurement in pp collisions at $\sqrt{s} = 7$ TeV and to the expectations from PYTHIA pp simulations and NLO pQCD calculations at $\sqrt{s_{\rm NN}} = 5.02$ TeV.

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