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arXiv 1702.00804nucl-exhep-ex
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在LHC上Pb-Pb和p-Pb碰撞中喷流质量的首次测量

First measurement of jet mass in Pb-Pb and p-Pb collisions at the LHC

ALICE Collaboration

摘要:

这封信介绍了在$\sqrt{s_{\rm NN}}$ = 2.76 TeV和5.02 TeV的Pb-Pb和p-Pb碰撞喷流质量的第一次测量。在对撞机能量下的核碰撞中产生的热量子色动力学(QCD)物质中,喷流能量和喷流质量都对喷流猝灭敏感。使用反$k_{\rm T}$射流算法和分辨率参数$R = 0.4$从带电粒子重构射流。喷流在赝快度范围$|η_{\rm{jet}}|<0.5$和横向动量在60 GeV/ $c$和120 GeV/ $c$之间的三个间隔中测量。中心Pb-Pb碰撞中的射流质量的测量进行比较,在p-Pb参考碰撞中测量的射流质量,真空事件发生器,和模型,包括射流淬火。据观察,喷流质量在中央铅铅碰撞是一致的不确定性与p-Pb参考测量。此外,在Pb-Pb碰撞中测得的喷流质量是不再现淬火模型在这封信中考虑,并被认为是符合PYTHIA的预期系统的不确定性。

英文摘要:

This letter presents the first measurement of jet mass in Pb-Pb and p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV and 5.02 TeV, respectively. Both the jet energy and the jet mass are expected to be sensitive to jet quenching in the hot Quantum Chromodynamics (QCD) matter created in nuclear collisions at collider energies. Jets are reconstructed from charged particles using the anti-$k_{\rm T}$ jet algorithm and resolution parameter $R = 0.4$. The jets are measured in the pseudorapidity range $|η_{\rm{jet}}|<0.5$ and in three intervals of transverse momentum between 60 GeV/$c$ and 120 GeV/$c$. The measurement of the jet mass in central Pb-Pb collisions is compared to the jet mass as measured in p-Pb reference collisions, to vacuum event generators, and to models including jet quenching. It is observed that the jet mass in central Pb-Pb collisions is consistent within uncertainties with p-Pb reference measurements. Furthermore, the measured jet mass in Pb-Pb collisions is not reproduced by the quenching models considered in this letter and is found to be consistent with PYTHIA expectations within systematic uncertainties.

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