Abstract
Many theories beyond the standard model involve an extra gauge group. The resulting gauge boson , in general mixed with the and the photon, may be massless or very light and very weakly coupled. It may be viewed as a generalized dark photon interacting with matter through a linear combination , involving in a grand-unified theory, presumably through , inducing effectively a very small repulsive force between neutrons. This new force, if long-ranged, may manifest through apparent violations of the equivalence principle. They are approximately proportional to , times a combination involving mostly . New forces coupled to or should lead to nearly opposite values of the Eötvös parameter , and to almost the same limits for or , as long as no indication for is found. We derive new limits from the first results of the MICROSCOPE experiment testing the equivalence principle in space. A long-range force coupled to or should verify or , and a force coupled to , . We also discuss, within supersymmetric theories, how such extremely small gauge couplings , typically , may be related to a correspondingly large term associated with a huge initial vacuum energy density, . The corresponding hierarchy between energy scales, by a factor , involves a very large scale , that may be associated with inflation, or supersymmetry breaking with a very heavy gravitino, leading to possible values of within the experimentally accessible range.
- Received 4 December 2017
DOI:https://doi.org/10.1103/PhysRevD.97.055039
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.
Published by the American Physical Society