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arXiv 1102.4706hep-ph
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逐事件流体动力学中热光子产生的增强

Enhancement of thermal photon production in event-by-event hydrodynamics

Rupa Chatterjee, Hannu Holopainen, Thorsten Renk, Kari J. Eskola

摘要:

热光子发射被广泛认为反映了超相对论性重离子碰撞中产生的介质的最早、最热演化阶段的性质。以前的光子发射的计算已经进行了使用流体动力学介质的描述与平滑,平均的初始条件。最近,更复杂的流体动力学模型,计算观测值的平均在许多演变与事件的波动初始条件(IC)已被开发。鉴于它们与早期动力学的直接联系,热光子发射似乎是探测介质初始状态波动的理想观测。在这项工作中,我们表明,包括在IC中的波动可能会导致增强的热光子产率的约2倍的区域$2 < p_T < 4$ GeV/ $c$(其中热光子生产占主导地位的直接光子产率)相比,使用平滑的情况下,平均IC。因此,一个更好的协议与PHENIX数据被发现。这可以理解的热光子产生的强烈的温度依赖性,转化为一个事件中的“热点”的存在的敏感性,从而建立热光子作为一个合适的探针来表征IC波动。

英文摘要:

Thermal photon emission is widely believed to reflect properties of the earliest, hottest evolution stage of the medium created in ultra-relativistic heavy-ion collisions. Previous computations of photon emission have been carried out using a hydrodynamical medium description with smooth, averaged initial conditions. Recently, more sophisticated hydrodynamical models which calculate observables by averaging over many evolutions with event-by-event fluctuating initial conditions (IC) have been developed. Given their direct connection to the early time dynamics, thermal photon emission appears an ideal observable to probe fluctuations in the medium initial state. In this work, we demonstrate that including fluctuations in the IC may lead to an enhancement of the thermal photon yield of about a factor of 2 in the region $2 < p_T < 4$ GeV/$c$ (where thermal photon production dominates the direct photon yield) compared to a scenario using smooth, averaged IC. Consequently, a much better agreement with PHENIX data is found. This can be understood in terms of the strong temperature dependence of thermal photon production, translating into a sensitivity to the presence of 'hotspots' in an event and thus establishing thermal photons as a suitable probe to characterize IC fluctuations.

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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