A class of ghost-free theories in symmetric teleparallel geometry

Antonio G. Bello-Morales, Jose Beltrán Jiménez, Alejandro Jiménez Cano, Antonio L. Maroto, Tomi S. Koivisto

Published 2024-06-27Version 1

Theories formulated in the arena of teleparallel geometries are generically plagued by ghost-like instabilities or other pathologies that are ultimately caused by the breaking of some symmetries. In this work, we construct a class of ghost-free theories based on a symmetry under Transverse Diffeomorphisms that is naturally realised in symmetric teleparallelism. We explicitly show their equivalence to a family of theories with an extra scalar field plus a global degree of freedom and how Horndeski theories and healthy couplings to matter fields can be readily accommodated.