Why scalar field is indispensable in Teleparallel Gravity theory? (2407.09586v1)

Abstract: Teleparallel gravity theories were proposed as alternatives to the dark energy and modified theories of gravity. However, both the metric and symmetric teleparallel gravity theories have been found to have serious pathologies, such as coupling issues and Ostrogradski's instability leading to ghost degrees of freedom. In this article we explore the fact that the theories are at-least free from the issue of `Branched Hamiltonian' though, nonetheless, early inflation as well as a viable radiation era may only be driven by a scalar field.