WMAP Bounds on Braneworld Tachyonic Inflation

We analyse the implications of the Wilkinson Microwave Anisotropy Probe (WMAP) results for a braneworld tachyonic model of inflation. We find that WMAP bounds on $n_s$ allow us to constrain significantly the parameter space of the model; in particular, extremely weak string coupling is required, $g_s \sim 10^{-15}$. Moreover, our analysis shows that the running of the scalar spectral index is within the bounds determined by WMAP for the allowed range of model parameters; however, it is not possible to obtain $n_s>1$ on large scales and $n_s<1$ on small scales.