Erratum: Sourced scalar fluctuations in bouncing cosmology

Abstract

In “Sourced scalar fluctuations in bouncing cosmology” JCAP07(2019)050 we calculated the scalar and tensor power spectra generated by sourced fluctuations due to coupling between the scalar field, which holds most of the energy density of the universe, and a gauge field for a general FLRW metric. The coupling between the scalar field φ and the gauge field was denoted by the function I(φ)≡ I(φ(τ))=(−τ)−n, where the last equality is the temporal behavior of the coupling as a function of conformal time τ by construction. We first wrote down I(φ) in “Gravitational waves in bouncing cosmologies from gauge field production”, JCAP09(2016)017, but made an error in the expression of I(φ). In that work, all calculations were done using I=(−τ)−n, and as a result, this error did not have any consequences. However, in the present work, dI/dφ appears in the scalar source term, which is crucial in determining the value of r, and incorrectly yielded r≃ 0.85 for a nearly scale invariant spectrum. Upon correcting the error we find r≃1/9, an order of magnitude smaller, but still not consistent with current data. The rest of the theoretical and phenomenological results including potential detection by LIGO and LISA are unchanged.