Complete constraints on a nonminimally coupled chaotic inflationary scenario from the cosmic microwave background

Eiichiro Komatsu and Toshifumi Futamase
Astronomical Institute, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan


We present complete constraints imposed from observations of the cosmic microwave background radiation (CMBR) on the chaotic inflationary scenario with a nonminimally coupled inflaton field proposed by Fakir and Unruh (FU). Our constraints are complete in the sense that we investigate both the scalar density perturbation and the tensor gravitational wave in the Jordan frame, as well as in the Einstein frame. This makes the constraints extremely strong without any ambiguities due to the choice of frames. We find that the FU scenario generates tiny tensor contributions to the CMBR relative to chaotic models in minimal coupling theory, in spite of its spectral index of scalar perturbation being slightly tilted. This means that the FU scenario will be excluded if any tensor contributions to CMBR are detected by the forthcoming satellite missions. Conversely, if no tensor nature is detected despite the tilted spectrum, a minimal chaotic scenario will be hard to explain and the FU scenario will be supported.


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