The Robustness of n_s < 0.95 in Racetrack Inflation

Understand

A spectral index n_s < 0.95 appears to be a generic prediction of racetrack inflation models.

• Reducing a general racetrack model to a single-field inflation model with a simple potential, we obtain an analytic expression for the spectral index, which explains this result.
• By considering the limits of validity of the derivation, possible ways to achieve higher values of the spectral index are described, although these require further fine-tuning of the potential.