Galante Mario, Kallosh Renata, Linde Andrei, Roest Diederik
Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Department of Physics and SITP, Stanford University, Stanford, California 94305, USA.
Phys Rev Lett. 2015 Apr 10;114(14):141302. doi: 10.1103/PhysRevLett.114.141302. Epub 2015 Apr 8.
Recently, several broad classes of inflationary models have been discovered whose cosmological predictions, in excellent agreement with Planck, are stable with respect to significant modifications of the inflaton potential. Some classes of models are based on a nonminimal coupling to gravity. These models, which we call ξ attractors, describe universal cosmological attractors (including Higgs inflation) and induced inflation models. Another class describes conformal attractors (including Starobinsky inflation and T models) and their generalization to α attractors. The aim of this Letter is to elucidate the common denominator of these attractors: their robust predictions stem from a joint pole of order 2 in the kinetic term of the inflaton field in the Einstein frame formulation prior to switching to the canonical variables. Model-dependent differences only arise at subleading level in the kinetic term. As a final step towards the unification of the different attractors, we introduce a special class of ξ attractors which is fully equivalent to α attractors with the identification α=1+(1/6ξ). While r is generically predicted to be of the order 1/N^{2}, there is no theoretical lower bound on r in this class of models.
最近，人们发现了几大类暴胀模型，其宇宙学预测与普朗克卫星数据高度吻合，并且对于暴胀子势的显著修正具有稳定性。某些模型类别基于与引力的非最小耦合。我们将这些模型称为ξ吸引子，它们描述了通用的宇宙学吸引子（包括希格斯暴胀）和诱导暴胀模型。另一类描述了共形吸引子（包括斯塔罗宾斯基暴胀和T模型）及其向α吸引子的推广。本信函的目的是阐明这些吸引子的共同特征：它们稳健的预测源于在转换到正则变量之前，爱因斯坦框架表述中暴胀子场动能项里的一个二阶联合极点。模型相关的差异仅出现在动能项的次主导水平。作为迈向不同吸引子统一的最后一步，我们引入了一类特殊的ξ吸引子，它与α吸引子完全等价，其中α = 1 + (1/6ξ)。虽然一般预测r的量级为1/N²，但在这类模型中r没有理论下限。
