Inflationary cross-correlations of a non-minimal spectator and their soft limits
Jul 14, 2023Citations per year
Abstract: (IOP)
Light spectator fields may not be dynamically relevant for the inflationary phase of theearly universe, but they can still induce interesting imprints on cosmological observables. Inthis paper, we compute the cross-correlations of the inflationary perturbations, both scalar andtensor, with the fluctuations of a non-minimally interacting spectator field using the in-informalism and investigate the consistency relations associated with such cross-correlations. Inparticular, the scalar consistency relation is derived semi-classically by generalizing theconsistency relation obtained earlier for cosmic magnetic fields. Notably, we find that thedirect coupling between the inflaton and the spectator solely determines the local non-linearityparameter associated with the scalar cross-correlation during slow-roll inflation, regardless ofthe specific form of the Lagrangian for the spectator field. Further, we calculate the tensorcorrelation with spectator fluctuations, explore the associated soft limits, and demonstrate theviolation of the conventional tensor consistency relation with a non-minimal derivativecoupling. Our analysis stresses that the violation of tensor consistency relations does notnecessarily imply the superhorizon evolution of tensor modes. Instead, such violations can arisedue to the non-minimal derivative coupling of the spectator field to gravity. Finally, we discussthe wider implications of our results in the context of cosmological soft theorems.Note:
- v1: 23 pages; v2: 23 pages, minor corrections, accepted for publication in JCAP
- inflation
- non-gaussianity
- physics of the early universe
- primordial magnetic fields
- coupling: derivative
- inflation: slow-roll approximation
- correlation: tensor
- spectator
- nonminimal
- fluctuation
References(97)
Figures(0)
- [1]
- [2]
- [3]
- [4]
- [5]
- [7]
- [8]
- [9]
- [10]
- [11]
- [12]
- [13]
- [14]
- [15]
- [16]
- [17]
- [18]
- [19]
- [20]
- [21]
- [22]
- [23]
- [25]