高能核碰撞中喷注内底夸克的径向分布
Radial profile of bottom quarks in jets in high-energy nuclear collisions
AI总结：
本研究首次利用SHERPA和SHELL模型探究了LHC下Pb+Pb碰撞中喷注内B介子的径向分布，发现喷注淬火使其分布变窄而D介子变宽，揭示了质量相关的扩散与耗散竞争机制。
摘要：
重夸克（HQ）与其标记喷注之间的角关联是探究相对论重离子碰撞中介质内部分子相互作用潜在的新工具。在本研究中，我们首次对LHC下Pb+Pb碰撞中喷注内B介子的径向分布进行了理论研究。p+p碰撞中底夸克标记喷注的初态产生由SHERPA计算，该程序将次领头阶矩阵元与部分子簇射的贡献相匹配；而穿越QGP的大质量夸克则由Monte Carlo模型SHELL描述，该模型能在Langevin演化框架下同时模拟轻味和重味的介质内能量损失。在p+p碰撞中，我们发现在较低的$p_T^Q$下，喷注内重味的径向分布对重夸克质量敏感。在$\rm \sqrt{s_{NN}}=5.02$ TeV的$0-10\\%$ Pb+Pb碰撞中，我们观察到在$\rm 4<p_T^Q<20$ GeV范围内，喷注内B介子径向分布的修正模式与D介子相反：喷注淬火效应使喷注内B介子的径向分布变窄，而使喷注内D介子的径向分布变宽。我们发现，在A+A碰撞中，从较高$\rm p_T^Q> 20$ GeV区域耗散下来的贡献自然具有更窄的初始分布，从而导致更窄的径向分布修正模式；然而，重味介质内相互作用的扩散特性将产生更宽的径向分布修正模式。这两种效应因此相互竞争和抵消，喷注内的b夸克从前者获益更多，且与喷注内的c夸克相比受到的扩散效应较小。这些发现可以在未来LHC的实验测量中进行检验，以更好地理解喷注淬火的质量效应。
英文摘要：
Angular correlations between heavy quark (HQ) and its tagged jet are potentially new tools to gain insight into the in-medium partonic interactions in relativistic heavy-ion collisions. In this work, we present the first theoretical study on the radial profiles of B mesons in jets in Pb+Pb collisions at the LHC. The initial production of bottom quark tagged jet in p+p is computed by SHERPA which matches the next-to-leading order matrix elements with contributions of parton shower, whereas the massive quark traversing the QGP described by a Monte Carlo model SHELL which can simultaneously simulate light and heavy flavor in-medium energy loss within the framework of Langevin evolution. In p+p collisions, we find that at lower $p_T^Q$ the radial profiles of heavy flavors in jets are sensitive to the heavy quark mass. In $0-10\%$ Pb+Pb collisions at $\rm \sqrt{s_{NN}}=5.02$ TeV, we observe an inverse modification pattern of the B mesons radial profiles in jets at $\rm 4<p_T^Q<20$ GeV compared to that of D mesons: the jet quenching effects narrow the jet radial profile of B mesons in jets while broaden that of D mesons in jets. We find that in A+A collisions, the contribution dissipated from the higher $\rm p_T^Q> 20$ GeV region naturally has a narrower initial distribution and consequently leads to a narrower modification pattern of radial profile; however the diffusion nature of the heavy flavor in-medium interactions will give rise to a broader modification pattern of radial profile. These two effects consequently compete and offset with each other, and the b quarks in jets benefit more from the former and suffers less diffusion effect compared to that of c quarks in jets. These findings can be tested in the future experimental measurements at the LHC to gain better understanding of the mass effect of jet quenching.
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