Abstract We study two-field inflation derived from a single complex scalar field with a nonzero vacuum expectation value. The dynamics of inflation are governed by two parameters, the vacuum expectation value and the mass parameter of the phase mode, which together give rise to a rich variety of inflationary structures. We classify the possible trajectories of the two inflaton fields and identify the parameter regions consistent with current cosmological observations. Furthermore, we investigate the reheating process through the inflaton decay to right-handed neutrinos and the subsequent generation of lepton number within these regions. Our findings suggest that the presence of multiple scalar degrees of freedom can significantly alter the conditions for successful reheating and leptogenesis.
Abe et al. (2026) studied this question.