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arXiv · 1108.0981

Effective Field Theory and Decoupling in Multi-field Inflation: An Illustrative Case Study

Gary Shiu·Jiajun Xu
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Abstract

We explore the effects of heavy degrees of freedom on the evolution and perturbations of light modes in multifield inflation. We use a simple two-field model as an example to illustrate the subtleties of integrating out massive fields in a time-dependent background. We show that when adiabaticity is violated due to a sharp turn in field space, the roles of massive and massless field are interchanged, and furthermore the fields are strongly coupled; thus the system cannot be described by an effective single field action. Further analysis shows that the sharp turn imparts a non Bunch-Davis component in each perturbation mode, leading to oscillatory features in the power spectrum, and a large resonantly enhanced bispectrum.

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Gary Shiu, Jiajun Xu. 2011-08-12. Effective Field Theory and Decoupling in Multi-field Inflation: An Illustrative Case Study. https://doi.org/10.1103/physrevd.84.103509

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