Curvature perturbation spectrum in two-field inflation with a turning trajectory

Abstract

We revisit a two-component inflaton model with a turning trajectory in thefield space, where the field slowly rolls down along the trajectory.We consider the casewhen the effective mass in the direction perpendicular to the trajectory,namely the isocurvature direction, is either of the same order as or muchlarger than the Hubble parameter. Assuming that the turning angularvelocity is small, we compute analytically thecorrections to the power spectrum ofcurvature perturbation caused by the mediation of the heavy isocurvatureperturbation, and compare our analytic results with the numerical ones.Especially, when Meff2 ≫ H2, wefind that it is proportional to Meff−2.This result is consistent with the one obtained previously by aneffective field theory approach.