标题： 反弹Galileon宇宙学 显示英文标题

标题： Bouncing Galileon Cosmologies

摘要： 我们展示了共形Galileon模型的非奇异性、齐次且各向同性的反弹解。我们证明这类解必然以辐射主导的收缩阶段开始。随后进入一个五重情景，在此情景中背景方程状态跨越了宇宙常数边界，允许发生非奇异反弹，接着是Galilean创生。我们在这一背景下分析了宇宙扰动谱。我们的结果显示扰动演化平稳且无任何病态现象，但绝热模形成蓝倾斜谱。为了达到当前观测所需的标度不变原初功率谱，我们引入了一个与Galileon动能耦合的轻量标量场。我们发现了两种能够产生标度不变谱的耦合方式，其中一种需要对初始条件进行精细调节。该模型还预测引力波谱为蓝倾斜，这是由于收缩阶段的量子真空涨落所导致。 显示英文摘要

摘要： We present nonsingular, homogeneous and isotropic bouncing solutions of the conformal Galileon model. We show that such solutions necessarily begin with a radiation-dominated contracting phase. This is followed by a quintom scenario in which the background equation of state crosses the cosmological constant boundary allowing for a nonsingular bounce which in turn is followed by Galilean Genesis. We analyze the spectrum of cosmological perturbations in this background. Our results show that the fluctuations evolve smoothly and without any pathology, but the adiabatic modes form a blue tilted spectrum. In order to achieve a scale-invariant primordial power spectrum as required by current observations, we introduce a light scalar field coupling to the Galileon kinetically. We find two couplings which yield a scale-invariant spectrum, one of which requires a fine tuning of the initial conditions. This model also predicts a blue tilted spectrum of gravitational waves stemming from quantum vacuum fluctuations in the contracting phase.