Abstract:

I will introduce and discuss aspects of Galileon theories: scalar field theories defined to have exactly second order field equations on flat space-times. The covariantization of flat space-time Galileons as well as their extensions to p-form and multifields will then be introduced together with the more general theories where one relaxes the hypothesis that field equations are second order. The recently discussed issue of d.o.f. counting in these theory will be discussed.