arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1004.3500hep-thgr-qchep-phnucl-th
收藏

基于演化AdS几何的重离子碰撞横向动力学

Heavy Ion Collisions with Transverse Dynamics from Evolving AdS Geometries

Anastasios Taliotis

摘要:

目前还没有一种方法可以从纯理论上构造强耦合重离子碰撞中产生的介质的应力-能量张量$(T_{μν})$。本文在这方面采取了一些措施。特别是,$T_{μν}$在强耦合和高能量的演变正在研究早期适当的时间$(τ)$。这是在AdS/CFT对偶的背景下通过构建AdS $_5$背景中的对偶几何的演化来实现的。改进了文献中的早期工作,两个入射核有一个碰撞参数$b$和一个非平凡的横剖面。核物质由两个冲击波模拟,对应于一个非零的五维体应力-能量张量$J_{MN}$。导出了小$τ$下$T_{μν}$的解析公式,并用于计算碰撞中产生的介质的动量各向异性和空间偏心率作为比率$\fracτ{b}$的函数。在中间$\fracτ{b}$的偏心率的结果同意定性的扰动理论的背景下,并通过使用流体动力学模拟得到的结果。最后,讨论了负能量密度问题及其与程函近似的自然联系。

英文摘要:

Currently there exists no known way to construct the Stress-Energy Tensor $(T_{μν})$ of the produced medium in heavy ion collisions at strong coupling from purely theoretical grounds. In this paper, some steps are taken in that direction. In particular, the evolution of $T_{μν}$ at strong coupling and at high energies is being studied for early proper times $(τ)$. This is achieved in the context of the AdS/CFT duality by constructing the evolution of the dual geometry in an AdS$_5$ background. Improving the earlier works in the literature, the two incident nuclei have an impact parameter $b$ and a non-trivial transverse profile. The nuclear matter is modeled by two shock waves corresponding to a non-zero five dimensional bulk Stress-Energy Tensor $J_{MN}$. An analytic formula for $T_{μν}$ at small $τ$ is derived and is used in order to calculate the momentum anisotropy and spatial eccentricity of the medium produced in the collision as a function of the ratio $\fracτ{b}$. The result for eccentricity at intermediate $\fracτ{b}$ agrees qualitatively with the results obtained in the context of perturbation theory and by using hydrodynamic simulations. Finally, the problem of the negative energy density and its natural connection to the eikonal approximation is discussed.

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。

↑