Gravity seminar - Christos Charmousis Seminar

 

Horndeski theories are the most general higher order scalar tensor theories admitting second order field equations. Discovered back in 1974 they present some interest at present as the simplest but non trivial modification of GR. In fact most modified theories of gravity, like bigravity, higher dimensional braneworlds, massive gravity etc admit some scalar tensor theory limit. They are rather general including for example GR, Brans-Dicke theory or f(R) theories for example. Hence Horndeski theories encompass many characteristics of modified gravity theories. Based on two theorems we will show how to obtain for a general subclass of these theories (admitting shift symmetry for the scalar field) spherically symmetric black hole solutions. For a specific theory we will give explicitly the general spherically symmetric and static solutions.