分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-08
摘要： We discuss a class of matrix models describing cosmology with a light-like singularity, generalizing the model proposed by Craps et al. in hep-th/0506180.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-08
摘要： We study a class of models in which the inflaton is minimally coupled to gravity with a term f(R)phiv2. We focus in particular on the case where f~R2, and the expansion of the scale factor is driven by the usual potential energy, while the rolling of the inflaton is driven by the non-minimal coupling. We show that the power spectrum is in general blue, and the problem of getting a running spectral index is eased. However, the inflaton potential must have a large second derivative in order to get a large running.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-08
摘要： We investigate the measure problem in the framework of inflationary cosmology. The measure of the history space is constructed and applied to inflationmodels. Using this measure, it is shown that the probability for the generalized single-field slow roll inflation to last for N e-folds is suppressed by a factor exp(-3N), and the probability for the generalized n-field slow roll inflation is suppressed by a much larger factor, exp(-3nN). Some non-inflationary models such as the cyclic model do not suffer from this difficulty.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2016-05-08
摘要： We use the stochastic approach to investigate a measure for slow roll eternal inflation. The probability for the universe to have a given Hubble radius can be calculated in this framework. In a solvable model, it is shown that the probability for the universe to evolve from a state with a smaller Hubble radius to one with a larger Hubble radius is dominated by the classical probability without the stochastic source, while the probability for the universe to evolve from a state with a larger Hubble radius to one with a smaller one is suppressed by exp(-Delta S), where the de Sitter entropy S arises naturally in this stochasticapproach.
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