Relic Gravitons In The Context Of String Theory

The emission of gravitational waves by multiple phenomena of astrophysical, cosmological and fundamental physics origin is predicted not only in Einstein's General Relativity Theory, but also in other theories of gravity. In this contribution we will sketch the main ideas and steps underlying the computation of primordial gravitational backgrounds arising from more general gravitational theories. We then apply it to obtain the graviton production in different transition epochs of the universe evolution, with gravity described by the Low Order String Effective Action. Finally, we end up pointing out the main characteristics and detection perspectives of the spectra