Testing Hybrid Natural Inflation with BICEP2

Abstract We analyse Hybrid Natural Inflation in view of the recent results for the tensor index reported by BICEP2. We find that it predicts a large running of the scalar spectrum which is potentially detectable by large scale structure through measurements of clustering of galaxies in combination with CMB data and by 21 cm forest observations. The running of the running is also relatively large becoming close to 10 − 2 . Along the way, we find general consistency relations at which observables are subject if the slow-roll approximation is imposed. Failure to satisfy these equations by the values obtained for the observables in surveys would be a failure of the slow-roll approximation itself.