Massive gravity and Bi-metric gravity as consistent theories of massive spin-2 fields.

by Dr Fawad Hassan (Fysikum)

Tuesday 7 Feb 2012, 13:15 → 14:15 Europe/Stockholm

FA32

This talk will describe the recent construction of consistent (ghost free) theories of massive spin-2 fields and their interpretation as theories of massive gravity and bi-metric gravity. While General Relativity is a theory of a massless spin-2 field, obtaining consistent non-linear theories of massive spin-2 fields has been a long standing problem since the original work of Pauli and Fierz in 1939. In fact, in 1972 and again in 2005, it was argued that such consistent theories may not even exist. This is puzzling since at least massive spin-2 mesons do exist in nature. It is also in contrast with spin-1 fields, where consistent theories exist for both the massless case (photon) and the massive case (W- and Z-bosons, vector mesons). However, over the past one year, theories of massive spin-2 fields have been constructed and shown to be consistent (ghost free). This has also been extended to theories of interacting massive and massless spin-2 fields. As a straightforward application, such theories can be regarded as theories of modified gravity, that is, massive gravity and bi-metric gravity. The talk will review recent progress in this field at a level understandable to non-experts.