Can the graviton have a mass ?

Who: Cédric Deffayet (IAP & IHES)
When: Monday, October 23, 2017 at 14:15
Where: The CP³ meeting room

In General Relativity (GR), the leading description we have today of gravity, the graviton (or a vanilla gravitational wave) is strictly massless. This is reflected on the infinite range of the gravitational interaction. However, almost since the first formulation of GR, came also the wish to change the large distance behaviour of gravity by making the graviton somehow massive. On this road, various obstructions were discovered (in particular in the 70’s) some long thought to be insuperable. However, the idea to make the graviton massive came back in the beginning of this century with the first attempts to replace dark energy by a modification of gravity at cosmological distances. The first attempt of this kind, formulated in the framework of the so-called DGP model, lead to recent developments which culminated in several discoveries in the years 2010 showing that the above mentioned obstructions can in fact be overcome but also to other result reaching further than massive gravity strictly speaking. We will review these issues both at the historical and conceptual level, underlying also some of the leftover issues.