arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2003.07431gr-qcastro-ph.CO
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标量-张量引力理论的暴胀平衡位形

Inflationary equilibrium configurations of scalar-tensor theories of gravity

Israel Quiros, Tame Gonzalez, Roberto De Arcia, Ricardo García-Salcedo, Ulises Nucamendi, Joel F. Saavedra

摘要:

在本文中,我们研究了基于标量-张量引力理论的暴胀宇宙学模型的渐近动力学。我们的主要目的是在单场暴胀模型的框架下探索相空间的全局结构。为此,我们强调相空间变量的适当选择。我们的研究结果表明,虽然单场通货膨胀是通用的意义上说,相空间中存在相应的临界点的广泛的潜在类,沿给定的相空间轨道-代表潜在的宇宙历史-的发生的通货膨胀阶段是相当依赖于初始条件。我们已经能够定量估计的相对概率(RP)的初始条件,导致缓慢滚动的通货膨胀。对于具有$ϕ^2$ -势的非最小耦合模型,我们的粗略估计产生几乎为零的相对概率:$10^{-13}\,\%\lesssim RP\ll 10^{-8}\,\%$。这些键在标量张量模型中得到了很大的改进,包括Brans-Dicke理论,其中相对几率为$1\,\%\lesssim RP\leq 100\,\%$。因此,慢卷暴胀确实是布兰-迪克暴胀模型中宇宙膨胀的一个自然阶段。同时也证实了具有任意势的真空Brans-Dicke理论的动力学是非混沌的。

英文摘要:

In this paper we investigate the asymptotic dynamics of inflationary cosmological models that are based in scalar-tensor theories of gravity. Our main aim is to explore the global structure of the phase space in the framework of single-field inflation models. For this purpose we make emphasis in the adequate choice of the variables of the phase space. Our results indicate that, although single-field inflation is generic in the sense that the corresponding critical point in the phase space exists for a wide class of potentials, along given phase space orbits -- representing potential cosmic histories -- the occurrence of the inflationary stage is rather dependent on the initial conditions. We have been able to give quantitative estimates of the relative probability (RP) for initial conditions leading to slow-roll inflation. For the non-minimal coupling model with the $ϕ^2$-potential our rough estimates yield to an almost vanishing relative probability: $10^{-13}\,\%\lesssim RP\ll 10^{-8}\,\%$. These bonds are greatly improved in the scalar-tensor models, including the Brans-Dicke theory, where the relative probability $1\,\%\lesssim RP\leq 100\,\%$. Hence slow-roll inflation is indeed a natural stage of the cosmic expansion in Brans-Dicke models of inflation. It is confirmed as well that the dynamics of vacuum Brans-Dicke theories with arbitrary potentials are non-chaotic.

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