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arXiv 1007.4949hep-thastro-ph.COhep-ph
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来自共形标量场的宇宙学密度扰动:红外特性和统计各向异性

Cosmological density perturbations from conformal scalar field: infrared properties and statistical anisotropy

M. Libanov, V. Rubakov

摘要:

我们考虑复共形标量场沿其负四次势滚下时产生的原初标量扰动。最初,这些是这个场的相位的扰动;它们在稍后的阶段被转换成绝热扰动。这种情况下的一个潜在的危险特征是在径向场方向上存在扰动,其具有红色功率谱。然而,我们表明,在小参数的线性顺序-四次自耦合-红外效应是完全无害的,因为它们可以被吸收到字段重新定义。然后,我们评估的统计各向异性固有的模型,由于存在的远程径向扰动。对于四次自耦合中的线性阶,统计各向异性不受红外效应的影响。后者出现在二次阶的自耦合,并导致在温和的(对数)增强相应的贡献的统计各向异性。由此产生的统计各向异性是一个较大的长期,然而,随着动量的增加而衰减,和一个较小的长期,这是独立的动量的组合。

英文摘要:

We consider a scenario in which primordial scalar perturbations are generated when complex conformal scalar field rolls down its negative quartic potential. Initially, these are the perturbations of the phase of this field; they are converted into the adiabatic perturbations at a later stage. A potentially dangerous feature of this scenario is the existence of perturbations in the radial field direction, which have red power spectrum. We show, however, that to the linear order in the small parameter - the quartic self-coupling - the infrared effects are completely harmless, as they can be absorbed into field redefinition. We then evaluate the statistical anisotropy inherent in the model due to the existence of the long-ranged radial perturbations. To the linear order in the quartic self-coupling the statistical anisotropy is free of the infrared effects. The latter show up at the quadratic order in the self-coupling and result in the mild (logarithmic) enhancement of the corresponding contribution to the statistical anisotropy. The resulting statistical anisotropy is a combination of a larger term which, however, decays as momentum increases, and a smaller term which is independent of momentum.

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