Effective field theory approach to quasi-single field inflation and effects of heavy fields

Abstract

We apply the effective field theory approach to quasi-single field inflation, which contains an additional scalar field with Hubble scale mass other than inflaton. Based on the time-dependent spatial diffeomorphism, which is not broken by the time-dependent background evolution, the most generic action of quasi-single field inflation is constructed up to third order fluctuations. Using the obtained action, the effects of the additional massive scalar field on the primordial curvature perturbations are discussed. In particular, we calculate the power spectrum and discuss the momentum-dependence of three point functions in the squeezed limit for general settings of quasi-single field inflation. Our framework can be also applied to inflation models with heavy particles. We make a qualitative discussion on the effects of heavy particles during inflation and those of sudden turning trajectory in our framework.

Large gauge transformation, soft theorem, and Infrared divergence in inflationary spacetime

“…(See also refs. [22][23][24][25].) Our study provides the conditions for the absence of such an imprint made after the Hubble crossing time of the comoving scale of our interest during inflation.…”

Loop Corrections to Standard Model fields in inflation

“…This is because the inflaton has to be coupled to the Standard Model fields with a coupling stronger than gravitational, to allow efficient reheating. The framework to study such non-Gaussianity of density fluctuations is quasi-single field inflation [9][10][11][12][13][14]. We hope to study the relevant signatures in a future work [20].…”

“…On top of that, the measurements of inflation observables through CMB or large scale structures have achieved impressive precision [4], and the precision will be further increased in the foreseeable future [5][6][7][8]. Based on this observation, it has been proposed recently that inflation can be used as a probe of the particle mass and spin spectra of new physics at high energies [9][10][11][12][13][14], and for this reason it is dubbed the "cosmological collider" by Arkani-Hamed and Maldacena [11].…”

Inflation and String Theory

“…1 These fields fluctuation quantum-mechanically during inflation and therefore have to be included in the computation of the primordial perturbations. The phenomenology of these models of quasisingle-field inflation [490] has been explored in [118,207,208,239,255,265,267,[491][492][493][494][495][496][497].…”