Disformal transformations are specific deformations of the metric, involving other fields and their derivatives. They have been used to relate different modified gravity models. For instance, mimetic and teleparallel gravities.
We will put forward a geometric formulation of disformal transformations, thereby elucidating the role of the non-metric fields therein. We will also identify key...
The Ashtekar connection-based approach of general relativity offers a compelling avenue for re-examining gravitational dynamics, particularly through its Hamiltonian formulation. This framework introduces the Barbero–Immirzi parameter, a factor whose role varies between classical and quantum treatments.
Classically, the Barbero–Immirzi parameter does not appear in the equations describing...
In this talk I will show our recent work on the quantization of Teleparallel Gravity (or TEGR), which is classically equivalent to GR. I compute the quadratically divergent counterterms that arise in the action, showing that they break the equivalence with GR at the quantum level. I then compute the logarithmically divergent counterterms and discuss their implications.
Scalar-tensor theories with derivative interactions form backgrounds which spontaneously break Lorentz invariance (cosmology during inflation or the dark energy era is the archetype). I will discuss how to think about the dynamics of free scalar perturbations, phonons, on general anisotropic backgrounds, showing that phonons move on null geodesics of an acoustic spacetime described by its own...
