Resonant particle production with nonminimally coupled scalar fields in preheating after inflation

We investigate a resonant particle production of a scalar field \χ coupled non-minimally to a spacetime curvature R (\ξ R \χ²) as well as to an inflaton field \φ (g²\φ²\χ²). In the case of g< \× 10⁻⁴, \ξ effect assists g-resonance in certain parameter regimes. However, for g>3 \× 10⁻⁴, g-resonance is not enhanced by \ξ effect because of \ξ suppression effect as well as a back reaction effect. If \ξ \≈ -20, the maximal fluctuation of produced \χ-particle is is almost the same as the minimally coupled case with g \≈ 1 \× 10⁻³.