arXiv 1411.32932014-11gr-qc

$f(T)$引力中的优美出口暴胀

Graceful Exit Inflation in $f(T)$ Gravity

G. G. L. Nashed, W. El Hanafy, Sh. Kh. Ibrahim

备注：: 22 pages, 6 Figures and 1 Table. Section 7 has been added. The list of references has been updated

摘要：

我们将$f(T)=T+αT^{2}$场方程的二次远程平行挠率标量应用于空间平坦的Friedmann-Robertson-Walker（FRW）模型。我们假设两个理想流体分量，物质分量具有固定的状态方程（EoS）参数$ω$，而扭转分量具有动态EoS。我们得到了一个有效的比例因子，使得一个优雅的出口膨胀模型，而不需要慢滚技术。我们进行了一个标准的宇宙学研究，以检查宇宙的演变。此外，有效的EoS显示一致的结果证实了一个平滑的相变从膨胀到辐射占主导地位的宇宙。我们考虑挠率是由标量场构成的情况。这种处理使我们能够诱导一个标量场敏感的时空对称性与有效的潜力，从二次$f(T)$引力。该模型由两个参数（$α,ω$）参数化，这两个参数都导出宇宙退出de Sitter膨胀。第一个是纯粹的引力和工程有效地在大哈勃政权的早期阶段，允许一个缓慢的滚动潜力。第二个参数$ω$是与动力学项耦合的类热修正，在后期的低哈勃区域有效。慢滚分析得到的势可以执行张量标量比和光谱指数参数与最近的普朗克和BICEP 2数据一致。宇宙学分析和标量场分析都显示了一致的结果。

英文摘要：

We apply a quadratic teleparallel torsion scalar of the $f(T)=T+αT^{2}$ field equations to the spatially flat Friedmann-Robertson-Walker (FRW) model. We assume two perfect fluid components, the matter component has a fixed equation of state (EoS) parameter $ω$, while the torsion component has a dynamical EoS. We obtain an effective scale factor allowing a graceful exit inflation model with no need to slow roll technique. We perform a standard cosmological study to examine the cosmic evolution. In addition, the effective EoS shows consistent results confirming a smooth phase transition from inflation to radiation dominant universe. We consider the case when the torsion is made of a scalar field. This treatment enables us to induce a scalar field sensitive to the spacetime symmetry with an effective potential constructed from the quadratic $f(T)$ gravity. The model is parameterized by two parameters ($α,ω$) both derive the universe to exit out of de Sitter expansion. The first is purely gravitational and works effectively at large Hubble regime of the early stage allowing a slow roll potential. The second parameter $ω$ is a thermal-like correction coupled to the kinetic term and works effectively at low Hubble regime of late stages. The slow roll analysis of the obtained potential can perform tensor-to-scalar ratio and spectral index parameters consistent with the recent Planck and BICEP2 data. Both cosmological and scalar field analyses show consistent results.

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摘要：

英文摘要：

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