Graviton non-gaussianity in ?-vacuum

A bstract We compute the leading order non-Gaussianity, i.e., bispectrum, of tensor perturbation in general ? -vacuum on de Sitter space relativity. In addition to well-known Bunch-Davies (BD) vacuum, there exits an infinite number invariant vacua represented by a real parameter and phase ? , with = 0 being BD vacuum. They are called -vacua. standard slow-roll inflation, as invariance no longer applies, -vacua lose its relevance rigorous sense. Nevertheless, if we assume that is only weakly dependent wavenumber appropriate UV cutoff, may consider pseudo- case false vacuum inflation where background spacetime pure Sitter, non-trivial (non-BD) could indeed be realized. find intriguing result bispectrum exponentially enhanced detectable observation even spectrum too small detected.