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arXiv 0710.4463hep-ph
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双轻子从ρ介子到重子密度高的区域有多敏感?

How Sensitive are Di-Leptons from Rho Mesons to the High Baryon Density Region?

S. Vogel, H. Petersen, K. Schmidt, E. Santini, C. Sturm, J. Aichelin, M. Bleicher

摘要:

我们表明,双轻子的测量可能只提供了一个有限的观点到最密集的重离子反应阶段。因此,在高重子密度下对介子和重子性质的可能研究,例如在GSI-HADES所做的和为FAIR-CBM所设想的,可能会观察到比目前在某些方法中预期的更弱的影响。我们认为,强吸收的共振在高的重子密度区域的重离子碰撞掩盖了信息从早期的热和稠密的阶段,由于碰撞加宽的总衰变宽度的强烈增加。为了获得更多的信息,我们还比较了目前使用的方法来提取双轻子的输运模拟-即发光,只有矢量介子从最终重子共振衰变和即时发射的双轻子,并发现一个强大的灵敏度的方法,特别是在FAIR和SPS能量。它表明明确的限制ρ介子(因此双轻子)的生产只在末态重子共振衰变提供了一个很强的偏向于相当低的重子密度。所示结果是使用标准设置从UrQMD v2.3计算获得的。

英文摘要:

We show that the measurement of di-leptons might provide only a restricted view into the most dense stages of heavy ion reactions. Thus, possible studies of meson and baryon properties at high baryon densities, as e.g. done at GSI-HADES and envisioned for FAIR-CBM, might observe weaker effects than currently expected in certain approaches. We argue that the strong absorption of resonances in the high baryon density region of the heavy ion collision masks information from the early hot and dense phase due to a strong increase of the total decay width because of collisional broadening. To obtain additional information, we also compare the currently used approaches to extract di-leptons from transport simulations - i.e. shining, only vector mesons from final baryon resonance decays and instant emission of di-leptons and find a strong sensitivity on the method employed in particular at FAIR and SPS energies. It is shown explicitly that a restriction to rho meson (and therefore di-lepton) production only in final state baryon resonance decays provide a strong bias towards rather low baryon densities. The results presented are obtained from UrQMD v2.3 calculations using the standard set-up.

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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