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arXiv 1407.7809nucl-ex
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在LHC上pp,p-Pb和Pb-Pb与ALICE碰撞中的双电子测量

Dielectron measurements in pp, p-Pb and Pb-Pb collisions with ALICE at the LHC

Markus K. Koehler

摘要:

电磁探测器是高能重离子碰撞产生的热而稠密介质的优秀信使。由于轻子的相互作用并不强烈,它们的光谱反映了碰撞的整个时空演化。周围介质可以导致相对于真空率的双电子产生的修改。为了量化重离子碰撞中的变化,pp碰撞中的测量值可以作为参考,而p-A碰撞的分析可以将冷核物质的影响从热的和稠密的介质中分离出来。在这篇论文中,介绍了用ALICE中心桶探测器测量双电子。不变的质量分布范围内的$ 0<m_{ee}<3 $ GeV/ $ c^{2} $进行比较,预期的产率从强子源的pp碰撞在$ \sqrt{s}=7 $ TeV,和p-Pb碰撞在$ \sqrt{s_{\rm NN}}=5.02 $ TeV。直接光子的截面测量通过虚光子在pp碰撞相比,从NLO pQCD计算的预测作为横向动量的函数。介绍了$ \sqrt{s_{\rm NN}}=2.76 $ TeV上铅-铅碰撞分析的现状。

英文摘要:

Electromagnetic probes are excellent messengers from the hot and dense medium created in high-energy heavy-ion collisions. Since leptons do not interact strongly, their spectra reflect the entire space-time evolution of the collision. The surrounding medium can lead to modifications of the dielectron production with respect to the vacuum rate. To quantify modifications in heavy-ion collisions, measurements in pp collisions serve as a reference, while the analysis of p-A collisions allows for the disentanglement of cold nuclear matter effects from those of the hot and dense medium. In this proceedings, dielectron measurements with the ALICE central barrel detectors are presented. The invariant mass distributions in the range $ 0<m_{ee}<3 $ GeV/$ c^{2} $ are compared to the expected yields from hadronic sources for pp collisions at $ \sqrt{s}=7 $ TeV, and for p-Pb collisions at $ \sqrt{s_{\rm NN}}=5.02 $ TeV. The cross section of direct photons measured via virtual photons in pp collisions is compared to predictions from NLO pQCD calculations as a function of the transverse momentum. The status of the analysis of Pb-Pb collisions at $ \sqrt{s_{\rm NN}}=2.76 $ TeV is presented.

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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