分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-09-27
摘要： We study cosmological solutions in the low-energy effective heterotic string theory, which is the Einstein gravity with Gauss-Bonnet term and the dilaton. We show that the field equations are cast into an autonomous system for flat internal and external spaces, and derive all the fixed points in the system. We also examine the time evolution of the solutions and whether the solutions can give (transient) accelerated expansion of our four-dimensional space in the Einstein frame.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-09-27
摘要： We consider the process of magnetogenesis in the context of nonsingular bounce cosmology. We show that large primordial magnetic #12;elds can be generated during contraction without encounter-ing strong coupling and backreaction issues. The #12;elds may seed large-scale magnetic #12;elds with observationally interesting strengths. This result leads to a the oretical constraint on the relation of the energy scale of the bounce cosmology to the number of e#11;ective e-folding of the contracting phase in the case of scale invariance for the power spectrum of primordial magnetic #12;elds. We show that this constraint can be satis#12;ed in a sizable region of the parameter space for the nonsingular bounce cosmology.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-09-27
摘要： We consider the possibility of inflationary magnetogenesis due to dynamical couplings of the elec-tromagnetic fields to gravity. We find that large primordial magnetic fields can be generated during inflation without the strong coupling problem,backreaction problem, or curvature perturbation problem, which seed large-scale magnetic fields with observationally interesting strengths.
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