Determining the regimes of cold and warm inflation in the supersymmetric hybrid model

Abstract

The SUSY hybrid inflation model is found to dissipate radiation during the inflationary period. Analysis is made of parameter regimes in which these dissipative effects are significant. The scalar spectral index, its running, and the tensor-scalar ratio are computed in the entire parameter range of the model. A clear prediction for strong dissipative warm inflation is found for n_S-1 \simeq 0.98 and a low tensor-scalar ratio much below 10^{-6}. The strong dissipative warm inflation regime also is found to have no \eta-problem and with the field amplitude much below the Planck scale. As will be discussed, this has important theoretical implications in permitting a much wider variety of SUGRA extensions to the basic model.