2018/12/31 by Ido Ben-Dayan, Judy Kupferman · 9 citations
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmic microwave background #Cosmological perturbation theory #Cosmology #Cosmology and Gravitation Theories #Curvature #Friedmann–Lemaître–Robertson–Walker metric #Galaxies: Formation, Evolution, Phenomena #Gauge theory #Scalar (mathematics) #Scalar field #Spectral line #astro-ph.CO #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1088/1475-7516/2019/07/050
published in Journal of Cosmology and Astroparticle Physics 2019(07), 050 (Institute of Physics) · Corrected an error in writing the coupling to the gauge field in terms of the scalar field and the corresponding equations. As a result, the prediction is r=1/9. Matches the published erratum
openalex created_date 2018/12/22 · openalex publication_date 2019/07/31 · arxiv created 2021/02/18 · arxiv updated 2021/02/19 · openalex updated_date 2026/08/05
We calculate the scalar power spectrum 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. For this purpose we calculate the curvature perturbation to second order in the presence of gauge fields, and show that the gauge fields behave like an additional potential term. We then apply the analysis to the case of slow-contraction. Due to the interaction between the scalar field and gauge fields additional 'sourced' tensor and scalar spectra are generated. The resulting spectra are chiral, slightly blue and arbitrarily close to scale invariance. The only difference between the tensor and scalar spectra is the coupling constant with an (1) numerical coefficient, and some momentum space polarization vectors. As a result the tilt of the spectra are the same. For the nearly scale invariant case, the momentum integration gives the same leading contribution. Hence, r ≃ 1 where the deviation from unity is controlled by the deviation from scale invariance, and is not in agreement with CMB observations. Deviating considerably from near scale invariance, and considering a bluer tilt with n T >0 .12, the model cannot account for CMB observations, but can be detected by LIGO and/or LISA in the future.