Department of Astronomy and Space Science, Kyung Hee University, Yong-in, South Korea.
Phys Rev Lett. 2010 Oct 29;105(18):181302. doi: 10.1103/PhysRevLett.105.181302. Epub 2010 Oct 27.
We study perturbations in the multifield axion N-flation model, taking account of the full cosine potential. We find significant differences from previous analyses which made a quadratic approximation to the potential. The tensor-to-scalar ratio and the scalar spectral index move to lower values, which nevertheless provide an acceptable fit to observation. Most significantly, we find that the bispectrum non-Gaussianity parameter f{NL} may be large, typically of order 10 for moderate values of the axion decay constant, increasing to of order 100 for decay constants slightly smaller than the Planck scale. Such a non-Gaussian fraction is detectable. We argue that this property is generic in multifield models of hilltop inflation.
我们研究了多场轴子 N 通胀模型中的微扰，考虑了完整的余弦势。我们发现与之前的分析有很大的不同，之前的分析对势进行了二次近似。张量-标量比和标量谱指数移到了较低的值，但仍然可以很好地拟合观测结果。最重要的是，我们发现双谱非高斯参数 f{NL}可能很大，对于中等大小的轴子衰变常数，典型值约为 10，对于稍小于普朗克尺度的衰变常数，增加到约 100。这样的非高斯分数是可以检测到的。我们认为这种性质在山顶通胀的多场模型中是普遍存在的。
