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Paper   IPM / Astronomy / 17452
School of Astronomy
  Title:   One-loop corrections in power spectrum in single field inflation
  Author(s):  H. Firouzjahi
  Status:   Published
  Journal: JCAP
  Vol.:  2023
  Year:  2023
  Supported by:            ipm IPM
  Abstract:
We revisit the one-loop correction in curvature perturbation power spectrum in models of single field inflation which undergo a phase of ultra slow-roll (USR) inflation. We include the contributions from both the cubic and quartic interaction Hamiltonians and calculate the one-loop corrections on the spectrum of the CMB scale modes from the small scale modes which leave the horizon during the USR phase. It is shown that the amplitude of one-loop corrections depends on the sharpness of the transition from the USR phase to the final slow-roll phase. For an arbitrarily sharp transition, the one-loop correction becomes arbitrarily large, invalidating the perturbative treatment of the analysis. We speculate that for a mild transition, the large one-loop corrections are washed out during the subsequent evolution after the USR phase. The implications for primordial black holes formation are briefly reviewed.

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