COBE Differential Microwave Radiometer Constraints on an Inflation Model with Nonminimal Scalar Field

We derive the power spectra of the scalar- and tensor-type structures generated in a chaotic-type inflation model based on nonminimally coupled scalar field with a self-interaction. By comparing contributions of both structures to the anisotropy of the cosmic microwave background radiation with the four-year COBE differential microwave radiometer data on quadrupole anisotropy we derive constraints on the ratio of self-coupling and nonminimal coupling constants, and the expansion rate in the inflation era. The requirement for a successful amount of inflation further constrains the relative amount of a tensor-type contribution.