Primordial perturbations and non-Gaussianities in DBI and general multifield inflation
Primordial perturbations and non-Gaussianities in DBI and general multifield inflation
复制标题
DOI：
10.1103/physrevd.78.063523
复制
发表时间：
2008-06
影响因子：
5
通讯作者：
D. Langlois;S. Renaux-Petel;D. Steer;Takahiro Tanaka
中科院分区：
文献类型：
--
作者：
D. Langlois;S. Renaux-Petel;D. Steer;Takahiro Tanaka
我们研究具有多个标量场和任意动力学项的一般暴胀模型中的宇宙扰动，特别强调狄拉克-玻恩-因菲尔德（DBI）暴胀的多场扩展。我们计算最一般情况下控制线性扰动动力学的二阶作用。专门研究 DBI 膨胀，我们证明绝热模式和熵模式以共同的有效声速传播，因此在声层交叉处被放大。在小声速极限下，我们发现熵模态的振幅远高于绝热模态的振幅。在一般情况下，我们还推导了三阶作用，这对于研究暴胀期间产生的原始非高斯性很有用。在 DBI 情况下，我们计算对非高斯性的主要贡献，这取决于绝热模式和熵模式。
We study cosmological perturbations in general inflation models with multiple scalar fields and arbitrary kinetic terms, with special emphasis on the multifield extension of Dirac-Born-Infeld (DBI) inflation. We compute the second-order action governing the dynamics of linear perturbations in the most general case. Specializing to DBI inflation, we show that the adiabatic and entropy modes propagate with a common effective sound speed and are thus amplified at sound horizon crossing. In the small sound speed limit, we find that the amplitude of the entropy modes is much higher than that of the adiabatic modes. We also derive, in the general case, the third-order action which is useful for studying primordial non-Gaussianities generated during inflation. In the DBI case, we compute the dominant contributions to non-Gaussianities, which depend on both the adiabatic and entropy modes.