We derive the gravitational waves for f(T,B) gravity, an extension of teleparallel gravity containing the torsion scalar T and the boundary term B, and demonstrate that it is equivalent to f(R) gravity. Gravitational waves, in this theory, show three polarizations: the two standard, plus and cross, of General Relativity, which are purely transverse, massless tensor polarization modes with two-helicity, and an additional massive scalar mode with zero-helicity. The last one is a mix of a longitudinal mode and a transverse breathing mode. The boundary term B excites the extra scalar polarization and the mass of scalar field breaks the symmetry of the TT gauge by adding a new degree of freedom, namely a single mixed scalar polarization.
@article{arxiv.1912.12469,
title = {Weak Field Limit and Gravitational Waves in $f(T,B)$ Teleparallel Gravity},
author = {Salvatore Capozziello and Maurizio Capriolo and Loredana Caso},
journal= {arXiv preprint arXiv:1912.12469},
year = {2020}
}
Comments
14 pages, accepted for publication in Eur. Phys. J. C