2020/08/07 by Takashi Hiramatsu, Kai Murai, Ippei Obata +1
Physics and Astronomy · #Amplitude #Anisotropy #Bispectrum #Cosmic microwave background #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Isotropy #Multipole expansion #Particle physics theoretical and experimental studies #Polarization (electrochemistry) #Tensor (intrinsic definition) #Tensor field #astro-ph.CO #hep-ph
paper · pdf · doi:10.1088/1475-7516/2021/03/047
25 pages, 4 figures
arxiv created 2020/08/07 · openalex created_date 2020/08/13 · openalex publication_date 2021/03/01 · arxiv updated 2021/03/31 · openalex updated_date 2026/08/06
Abstract We develop a possibility of generating tensor non-Gaussianity in a kind of anisotropic inflation, where a (1) gauge field is kinetically coupled to a spectator scalar field. Owing to this coupling, the coherent mode of the electric field appears and softly breaks the isotropy of the Universe. We compute the bispectrum of linearly-polarized tensor perturbations sourced by the gauge field and find that it is strongly red-tilted and has distinctive statistical anisotropies including higher-order multipole moments. Interestingly, the tensor bispectra with the specific combinations of linear polarization modes are dominant, and their amplitudes depend on the different sets of multipole moments. This new type of statistically-anisotropic tensor non-Gaussianity can be potentially testable with the upcoming cosmic microwave background B-mode polarization experiments.