Preheating of the nonminimally coupled inflaton field
2000; American Physical Society; Volume: 61; Issue: 10 Linguagem: Inglês
10.1103/physrevd.61.103501
ISSN1538-4500
AutoresShinji Tsujikawa, Kei-ichi Maeda, Takashi Torii,
Tópico(s)Quantum Electrodynamics and Casimir Effect
ResumoWe investigate preheating of an inflaton field $\ensuremath{\varphi}$ coupled nonminimally to a spacetime curvature by the method of Hartree approximations. In the case of a self-coupling inflaton potential $V(\ensuremath{\varphi})=\ensuremath{\lambda}{\ensuremath{\varphi}}^{4}/4,$ the dynamics of preheating changes by the effect of the negative $\ensuremath{\xi}.$ We find that the nonminimal coupling works in two ways. First, since the initial value of the inflaton field for reheating becomes smaller with the increase of $|\ensuremath{\xi}|,$ the evolution of the inflaton quanta is delayed for fixed $\ensuremath{\lambda}.$ Second, the oscillation of the inflaton field is modified and the nonadiabatic change around $\ensuremath{\varphi}=0$ occurs significantly. That makes the resonant band of the fluctuation field wider. Especially for strong coupling regimes $|\ensuremath{\xi}|\ensuremath{\gg}1,$ the growth of the inflaton fluctuation is dominated by the resonance due to the nonminimal coupling, which leads to a significant enhancement of low momentum modes. Although the final variance of the inflaton fluctuation does not change significantly compared with the minimally coupled case, we have found that the energy transfer from the homogeneous inflaton to created particles efficiently occurs for $\ensuremath{\xi}\ensuremath{\lesssim}\ensuremath{-}60.$
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