https://hal-insu.archives-ouvertes.fr/insu-03874799Nilsson, Nils A.Nils A.NilssonSYRTE - Systèmes de Référence Temps Espace - INSU - CNRS - Institut national des sciences de l'Univers - Observatoire de Paris - PSL - Université Paris sciences et lettres - SU - Sorbonne Université - CNRS - Centre National de la Recherche ScientifiqueExplicit spacetime-symmetry breaking and the dynamics of primordial fieldsHAL CCSD2022[SDU] Sciences of the Universe [physics]POTHIER, Nathalie2022-11-28 10:39:442023-03-13 11:17:182022-11-28 10:39:44enJournal articles10.1103/PhysRevD.106.1040361We study the effects of explicit spacetime-symmetry breaking on primordial tensor fluctuations using an effective-field theory for Lorentz/CPT violation. We find that the graviton is still massless, but that the propagation speed of tensor modes is modified, and we obtain a constraint on the coefficient determining the symmetry breaking on the order of 10<SUP>-15</SUP> from the recent measurements of the speed of gravity. Due to the symmetry breaking, the de-Sitter phase is modified, and during this inflationary epoch, the power spectrum assumes a slow oscillation around the general-relativity limit; further, we find that the primordial tensor power spectrum retains its scale invariance, but that the amplitude is modified. We also find that the modes which become subhorizon during radiation domination acquire a phase shift proportional to the coefficient for Lorentz violation.