Continuous spectrum on cosmological collider

Abstract We study the effects of a massive field with continuous spectrum (continuum isocurvaton) on inflationary bispectrum in squeezed limit. As concrete example, we extend quasi-single inflation model to include continuum isocurvaton well-motivated spectral density from extra dimensions and focus contribution single exchange. In contrast usual case without spectrum, amplitude has damping feature deep limit, which can be strong evidence for spectrum.