We extend previous work on the minimal D-term inflation model modified by Right-Handed ( RH ) sneutrino fields to include additional inflaton-sector SUGRA corrections and two-field inflation effects .
We show that SUGRA corrections simultaneously allow n _ { s } to be within 3-year WMAP limits and the cosmic string contribution to the CMB power spectrum to be less than 5 \% .
For gauge coupling g \leq 1 , the CMB contribution from cosmic strings is predicted to be at least 1 \% while the spectral index is predicted to be less than 0.968 for a CMB string contribution less than 5 \% .
Treating the inflaton-RH sneutrino system as a two-field inflation model , we show that the time-dependence of the RH sneutrino field strongly modifies the single-field results for values of RH sneutrino mass m _ { \Phi } > 0.1 H .
The running spectral index is \alpha \approx - 0.0002 when m _ { \Phi } < 0.1 H but increases to positive values as m _ { \Phi } / H increases , with \alpha > 0.008 for m _ { \Phi } > 1.0 H .