Extended constant-roll condition in non-canonical scalar field inflation

Abstract

In this work, we apply the extended constant-roll condition to non-canonical scalar fields. We use in particular two types of non-canonical fields, namely, the tachyon field and the Dirac–Born–Infeld (DBI) field. We assume, in particular, that the tachyon scalar field satisfies the condition [Formula: see text], while the DBI scalar field satisfies the condition [Formula: see text]. We use the extended constant-roll condition to calculate the inflation indices for each of these non-canonical fields. In order to test the extended constant-roll condition, we use three types of potentials, namely chaotic potential, linear power-law potential and exponential potential, and choose power-law and exponential forms for the smooth function [Formula: see text]. It is then shown that the models under consideration are compatible with the latest Planck 2018 constraints.