paper

Primordial gravitational waves from spontaneous Lorentz symmetry breaking

arXiv:2501.14395 · doi:10.1016/j.physletb.2025.139597

Abstract

We study the effect of Spontaneous Lorentz Symmetry Breaking (SLSB) on Primordial Gravitational Waves (PGWs) generated during inflation. The SLSB is induced by a time-like Bumblebee vector field which is non-minimally coupled to the Ricci tensor in the Friedmann-Lemaître-Robertson-Walker background. The power spectrum and GW amplitude are computed to investigate how Lorentz violation leaves observable imprints. We calculate the GW strain amplitude over frequencies , for a range of the dimensionless Lorentz-violating parameter, , which essentially comes from a slight sensitivity to the equation of state for dark energy. For positive values, the amplitude of GW shows a mild suppression compared to the standard cosmological scenario . This effect could be observable with detectors like SKA, -Ares, and BBO. Conversely, negative values amplify the GW amplitude, enhancing detectability by both SKA, -Ares, and BBO, as well as by THEIA and DECIGO. Notably, the GW strain amplitude increases by an order of magnitude as moves from 0 to , improving prospects for detection in high-sensitivity detectors like THEIA and DECIGO.

10 pages, 02 figures, double column, accepted in Physics Letters B

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