Gravitational waves from double hybrid inflation

Abstract

We present a two stage hybrid inflationary scenario in non-minimal supergravity which can predict values of the tensor-to-scalar ratio of the order of few × 10 −2 . For the parameters considered, the underlying supersymmetric particle physics model possesses two inflationary paths, the trivial and the semi-shifted one. The trivial path is stabilized by supergravity corrections and supports a first stage of inflation with a limited number of e-foldings. The tensor-to-scalar ratio can become appreciable while the value of the scalar spectral index remains acceptable as a result of the competition between the relatively mild supergravity corrections and the strong radiative corrections to the inflationary potential. The additional number of e-foldings required for solving the puzzles of hot big bang cosmology are generated by a second stage of inflation taking place along the semi-shifted path. This is possible only because the semi-shifted path is almost perpendicular to the trivial one and, thus, not affected by the strong radiative corrections along the trivial path and also because the supergravity effects remain mild. The requirement that the running of the scalar spectral index remains acceptable limits the possible values of the tensor-to-scalar ratio not to exceed about 5 × 10 −2 . Our model predicts the formation of an unstable string-monopole network, which may lead to detectable gravity wave signatures in future space-based laser interferometer observations.

Monopoles, strings, and necklaces in SO(10) and E6

“…(65) in ref. [45] -is consistent. Now the question arises under what circumstances the required t H can be obtained.…”

“…For the analysis of this case, we follow ref. [45]. The present abundance of these gravity waves is given by combining eqs.…”

Particles and the Universe

“…Alternatively, a more moderate inflation such as thermal inflation [34], associated with a phase transition occurring at a temperature of the order of the electroweak scale, can dilute them to an acceptable, but possibly measurable level. Cosmic strings from GUTs [35], on the other hand, can generate gravity waves [36], which will be possibly measurable [24,37,38] by future experiments. Finally, domain walls are [33] catastrophic and GUTs should be constructed so that they avoid them (see e.g.…”

Axion, μ term, and supersymmetric hybrid inflation

“…It should be noted that, reducing the parameter λ below 1, χ m is just rescaled by a factor λ −1/2 as one can see from Eq. (12). Consequently, in all these figures, χ is practically just multiplied by the same factor.…”