S and T Self-dualities in Dilatonic f(R) Theories
We search for theories, in general spacetime dimensions, that would incorporate a dilaton and higher powers of the scalar Ricci curvature such that they have exact S and/or T self-dualities. The theories we find are free of Ostrogradsky instabilities. We also show that within the framework we are confining ourselves a theory of the form mentioned above can not have both T and S dualities except for the case where the action is linear in the scalar curvature.