New constraints on multifield inflation with nonminimal coupling

Shinji Tsujikawa, Hiroki Yajima

Research output: Contribution to journalArticle

3 Citations (Scopus)


We study the dynamics and perturbations during inflation and reheating in a multifield model where a second scalar field (Formula presented) is nonminimally coupled to the scalar curvature (Formula presented) When (Formula presented) is positive, the usual inflationary prediction for large-scale anisotropies is hardly altered while the (Formula presented) fluctuation in sub-Hubble modes can be amplified during preheating for large (Formula presented) For negative values of (Formula presented) however, long-wave modes of the (Formula presented) fluctuation exhibit exponential increase during inflation, leading to the strong enhancement of super-Hubble metric perturbations even when (Formula presented) is less than unity. This is because the effective (Formula presented) mass becomes negative during inflation. We constrain the strength of (Formula presented) and the initial (Formula presented) by the amplitude of produced density perturbations. One way to avoid nonadiabatic growth of super-Hubble curvature perturbations is to stabilize the (Formula presented) mass through a coupling to the inflaton. Preheating may thus be necessary in these models to protect the stability of the inflationary phase.

Original languageEnglish
Number of pages1
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number12
Publication statusPublished - 2000

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)

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