Observational constraints on assisted k-inflation

Understand

We study observational constraints on the assisted k-inflation models in which multiple scalar fields join an attractor characterized by an effective single field $\phi$.

• This effective single-field system is described by the Lagrangian $P=Xg(Y)$, where $X$ is the kinetic energy of $\phi$, $\lambda$ is a constant, and $g$ is an arbitrary function in terms of $Y=X e^{\lambda \phi}$.
• Our analysis covers a wide variety of k-inflation models such as dilatonic ghost condensate, Dirac-Born-Infeld (DBI) field, tachyon, as well as the canonical field with an exponential potential.
• We place observational bounds on the parameters of each model from the WMAP 7yr data combined with Baryon Acoustic Oscillations (BAO) and the Hubble constant measurement.