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arXiv 2102.13080hep-exnucl-ex
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重离子碰撞中大面积喷流横动量谱的首次测量

First measurement of large area jet transverse momentum spectra in heavy-ion collisions

CMS Collaboration

摘要:

用CMS探测器研究了核子-核子质心能量为5.02 TeV的铅-铅(PbPb)和质子-质子(pp)碰撞中喷流的产生,所用PbPb和pp数据样本分别对应于404 pb $μ$和27.4 pb $^{-1}$的积分亮度。通过改变距离参数$R$,使用反$k_\mathrm{T}$算法重建具有不同区域的射流。测量使用射流的横向动量($p_\mathrm{T}$)大于200 GeV和在伪快度范围内的$|η|$ $\lt$ 2。为了揭示介质修改的喷流光谱中的PbPb碰撞,适当的归一化比率的光谱从PbPb和PP数据被用来提取喷流核修改因子的函数的PbPb碰撞中心,$p_\mathrm{T}$,并首次作为一个函数的$R$高达1.0。对于最中心的碰撞,观察到一个强大的抑制高$p_\mathrm{T}$射流重建与所有的距离参数,这意味着大量的射流能量分散到大的角度。喷流抑制对$R$的依赖性预计对喷流能量损失机制和介质响应都敏感,因此将数据与几个现代事件发生器和分析计算进行比较。所考虑的模型不能完全重现数据。

英文摘要:

Jet production in lead-lead (PbPb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV is studied with the CMS detector at the LHC, using PbPb and pp data samples corresponding to integrated luminosities of 404 $μ$b$^{-1}$ and 27.4 pb$^{-1}$, respectively. Jets with different areas are reconstructed using the anti-$k_\mathrm{T}$ algorithm by varying the distance parameter $R$. The measurements are performed using jets with transverse momenta ($p_\mathrm{T}$) greater than 200 GeV and in a pseudorapidity range of $|η|$ $\lt$ 2. To reveal the medium modification of the jet spectra in PbPb collisions, the properly normalized ratio of spectra from PbPb and pp data is used to extract jet nuclear modification factors as functions of the PbPb collision centrality, $p_\mathrm{T}$ and, for the first time, as a function of $R$ up to 1.0. For the most central collisions, a strong suppression is observed for high-$p_\mathrm{T}$ jets reconstructed with all distance parameters, implying that a significant amount of jet energy is scattered to large angles. The dependence of jet suppression on $R$ is expected to be sensitive to both the jet energy loss mechanism and the medium response, and so the data are compared to several modern event generators and analytic calculations. The models considered do not fully reproduce the data.

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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