1-5 July 2019
Faculty of Physics, University of Warsaw
Europe/Warsaw timezone

Scalar-tensor theories beyond Riemannian

5 Jul 2019, 09:50
20m
Faculty of Physics, University of Warsaw

Faculty of Physics, University of Warsaw

conference hall 0.03, Faculty of Physics, University of Warsaw ul. Pasteura 5, 02-093 Warszawa Poland
contributed talk Beyond V

Speaker

Katsuki Aoki (Yukawa Institute for Theoretical Physics, Kyoto University)

Description

We discuss scalar-tensor theories based on a non-Riemannian geometry, called the metric-affine geometry, where the metric and the connection are treated as independent variables. In the metric-affine formalism, the Einstein-Hilbert action enjoys an additional local symmetry, the projective symmetry, under a shift of the connection. We find that the projective symmetry can provide an Ostrogradky ghost-free structure of general scalar-tensor theories. The ghostly sector of the second-order derivative of the scalar is absorbed into the projective gauge mode when the unitary gauge can be imposed. We also find that, up to the quadratic order of the connection, the most general projective invariant theory is equivalent to the U-degenerate theory when the connection is integrated out and, if we further assume the Galileon-type self-interactions, the theory is equivalent to DHOST theory.

[1] Katsuki Aoki and Keigo Shimada, Galileon and generalized Galileon with projective invariance in a metric-affine formalism, 1806.02589.
[2] Katsuki Aoki and Keigo Shimada, Scalar-metric-affine theories: Can we get ghost-free theories from symmetry?, 1904.10175.

Primary authors

Katsuki Aoki (Yukawa Institute for Theoretical Physics, Kyoto University) Keigo Shimada (Tokyo Institute of Technology)

Presentation Materials