OKC/Nordita High-Energy Physics Theory seminar

Rethinking Horndeski theory: a new formalism for scalar-tensor theories of gravity

by Jose María Ezquiaga (IFT, Madrid)

132:028 ()


Nowadays, there is great interest in finding which is the most general Scalar-Tensor (ST) theory without ghost instabilities. In particular, this would be very useful for Cosmology because ST theories are used to parametrize deviations from GR and LCDM. In this sense, considerable effort is being placed in extending consistently Horndeski theory. In this talk, I will first review how to construct ghost-free theories and show how Horndeski theory arises, commenting also in the recent Beyond Horndeski models. Then, I will present a novel approach to build general ST theories that naturally incorporates the requirements to avoid instabilities. This new formalism affords great computational simplicity with a systematic structure. Finally, I will discuss its future applications.