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New class of generalized coupling theories

Justin C. Feng

In this talk, I present a new class of gravity theories which are characterized by a nontrivial coupling between the gravitational metric and matter mediated by an auxiliary rank-2 tensor. The actions generating the field equations are constructed so that these theories are equivalent to general relativity in a vacuum, and only differ from Einstein's theory within a matter distribution. This talk will focus on one of the simplest realizations of these theories. In this theory, termed the MEMe model, one can obtain an exact solution for a single perfect fluid. Furthermore, the propagation speed of gravitational radiation in matter is different from its value in vacuum and that this can be used to constrain the (single) additional parameter of the MEMe model. An analysis of the evolution of homogeneous and isotropic spacetimes in the MEMe model shows that there exist cosmic histories with both an inflationary phase and a dark era characterized by a different expansion rate.

2019 November 13, 15:30

Faculdade de Ciências da Universidade de Lisboa (C8.2.16)
Campo Grande, 1749-016 Lisboa

Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia