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arXiv 0902.1036nucl-thhep-phnucl-ex
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铅核在CERN SPS相对论碰撞的单光子再分析

Single photons from relativistic collision of lead nuclei at CERN SPS: A reanalysis

Rupa Chatterjee, Dinesh K. Srivastava, Sangyong Jeon

摘要:

本文对在CERN SPS上用WA 98实验测量的铅核相对论碰撞单光子产生进行了重新分析。的改进包括使用的iso-spin和阴影校正的NLO pQCD治疗使用的因子分解,重整化,和碎裂和使用的流体动力学适合于非中心的碰撞以及一个良好的测试状态方程承认夸克强子相变的快速光子生产。数据的定量解释需要一个大的初始温度(在约0.2 fm/ $c$的小的形成时间)和适度的增加,这可能是由于在核中的克罗宁效应的即时产量。该数据也可以用中等的初始温度(在约1 fm/ $c$的形成时间)和非常大的$K$ -因子乘以瞬时产率来解释。我们发现,不同的初始时间产生不同的值的椭圆流参数$v_2$热光子。我们还表明,测量热光子的$v_2$也可以区分有或没有相变的情况。

英文摘要:

We present a reanalysis of single photon production from relativistic collision of lead nuclei at CERN SPS measured by the WA98 experiment. The refinements include use of iso-spin and shadowing corrected NLO pQCD treatment for prompt photon production using an optimized scale for factorization, renormalization, and fragmentation and use of hydrodynamics suited for non-central collisions along with a well tested equation of state admitting a quark-hadron phase transition. A quantitative explanation of the data requires a large initial temperature (at a small formation time of about 0.2 fm/$c$) and a moderate increase in the prompt yield which could perhaps be attributed to the Cronin effect in nuclei. The data can also be explained using a moderate initial temperature (at a formation time of about 1 fm/$c$) with a very large $K$-factor multiplying the prompt yield. We show that different initial times give rise to different values for the elliptic flow parameter $v_2$ for thermal photons. We also show that a measurement of $v_2$ for thermal photons could also distinguish between the scenarios with or without a phase transition.

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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