Extended tachyon field using form invariance symmetry

Abstract

In this work we illustrate how form-invariance transformations (FIT) can be used to construct phantom and complementary tachyon cosmologies from standard tachyon field universes. First we show how these transformations act on the Hubble expansion rate, the energy density, and pressure of the tachyon field. Then we use the FIT to generate three different families of the tachyon field. In other words, the FIT generate new cosmologies from a known “seed” one, in particular applying the FIT to the ordinary tachyon field we obtain two types of tachyon species, denominated phantom and complementary tachyon. We see that the FIT allow us to pass from a non-stable cosmology to a stable one and vice-versa. Finally, as an example, we apply the transformations to an inverse square potential, V ∝ φ −2 , and generate the extended tachyon field.