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arXiv 1611.03393gr-qcastro-ph.CO
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电磁场与引力非最小耦合的各向异性暴胀

Anisotropic inflation with a non-minimally coupled electromagnetic field to gravity

Muzaffer Adak, Ozgur Akarsu, Tekin Dereli, Ozcan Sert

摘要:

我们考虑非极小引力模型的$Y(R) F^2$ -形式.我们研究了一个特殊的情况下,该模型的高阶导数被消除,但标量曲率$R$是通过约束$Y_RF_{mn}F^{mn} =-\frac{2}{κ^2}$保持动力学。所得到的有效流体可以用电磁场与真空的相互作用来表示,即真空的能量密度随$R$的变化而变化,而常规电磁场的能量密度则随$\frac{Y(R)}{2}$的变化而变化。我们给出了各向异性膨胀的精确解,假设宇宙的体积标度因子呈现幂律膨胀。方向标度因子不一定表现出幂律扩展,这将引起恒定的扩展各向异性,而是非平凡地扩展并引起最终收敛到非零常数的非单调演变的扩展各向异性。基于这一事实,我们讨论了各向异性的e折叠在膨胀过程中,通过考虑所观察到的标度不变性的CMB和要求宇宙经历相同数量的e折叠在所有方向上。我们计算了膨胀结束时的剩余膨胀各向异性,尽管由于膨胀各向异性的非单调行为,宇宙的所有轴在膨胀结束时都经历了相同数量的e-折叠。我们还讨论了在暴胀的前几次e折叠中修正电磁场的产生及其对真空的持续性,直到暴胀结束。

英文摘要:

We consider the non-minimal model of gravity in $Y(R) F^2$-form. We investigate a particular case of the model, for which the higher order derivatives are eliminated but the scalar curvature $R$ is kept to be dynamical via the constraint $Y_RF_{mn}F^{mn} =-\frac{2}{κ^2}$. The effective fluid obtained can be represented by interacting electromagnetic field and vacuum depending on $Y(R)$, namely, the energy density of the vacuum tracks $R$ while energy density of the conventional electromagnetic field is dynamically scaled with the factor $\frac{Y(R)}{2}$. We give exact solutions for anisotropic inflation by assuming the volume scale factor of the Universe exhibits a power-law expansion. The directional scale factors do not necessarily exhibit power-law expansion, which would give rise to a constant expansion anisotropy, but expand non-trivially and give rise to a non-monotonically evolving expansion anisotropy that eventually converges to a non-zero constant. Relying on this fact, we discuss the anisotropic e-fold during the inflation by considering observed scale invariance in CMB and demanding the Universe to undergo the same amount of e-folds in all directions. We calculate the residual expansion anisotropy at the end of inflation, though as a result of non-monotonic behaviour of expansion anisotropy all the axes of the Universe undergo the same of amount of e-folds by the end of inflation. We also discuss the generation of the modified electromagnetic field during the first few e-folds of the inflation and its persistence against to the vacuum till end of inflation.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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