Aspects of string-gas cosmology at finite temperature
Aspects of string-gas cosmology at finite temperature
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有限温度下弦气体宇宙学的各个方面
DOI：
10.1103/physrevd.67.123506
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发表时间：
2003
影响因子：
5
通讯作者：
S. Tsujikawa
中科院分区：
文献类型：
--
作者：
B. Bassett;M. Borunda;M. Serone;S. Tsujikawa
我们在膨胀引力下研究弦气体宇宙学，灵感来自于它在弦理论背景下自然产生的事实。我们的主要兴趣是弦气体的热力学处理及其对宇宙学的影响。在绝热近似、热力学平衡和一个小的环形宇宙作为初始条件下，我们数值求解了描述弦-气体热力学的两种不同制度下的相应运动方程：(i) Hagedorn制度，具有单一的尺度因子；（ii）几乎由辐射主导的制度，其中包括由最轻的Kaluza Klein和缠绕模式引起的主要修正，具有两个尺度因子。Hagedorn状态的尺度因子表现出非常缓慢的时间演化，能量几乎恒定，压力可以忽略不计。相比之下，在情况（ii）中，我们发现了有趣的宇宙学解，其中大维度继续膨胀，而小维度保持不可探测的小。
We study string-gas cosmology in dilaton gravity, inspired by the fact that it naturally arises in a string theory context. Our main interest is the thermodynamical treatment of the string-gas and the resulting implications for the cosmology. Within an adiabatic approximation, thermodynamical equilibrium and a small, toroidal universe as initial conditions, we numerically solve the corresponding equations of motions in two different regimes describing the string-gas thermodynamics: (i) the Hagedorn regime, with a single scale factor, and (ii) an almost-radiation dominated regime, which includes the leading corrections due to the lightest Kaluza Klein and winding modes, with two scale factors. The scale factor in the Hagedorn regime exhibits very slow time evolution with nearly constant energy and negligible pressure. By contrast, in case (ii) we find interesting cosmological solutions where the large dimensions continue to expand and the small ones are kept undetectably small.