On ghost-free extensions of general relativity: massive gravity, bimetric gravity and all that
by
Sayed Fawad Hassan(Stockholm University)
→
Europe/Stockholm
132:028
132:028
Description
The standard model of particle physics involves fields of spin 0, 1/2
and 1. It is well known that there exist consistent theories for
describing such fields in both massless and massive cases, and in
multiple copies. These theories are the building blocks of the
standard model. On the other hand, General Relativity is a classical
theory of a single massless spin-2 field. Unlike the lower spin cases,
it is highly non-trivial to generalize GR to theories of massive and
interacting multiple spin-2 fields. The source of difficulty is a
"ghost" instability that generically appears in such theories.
Although such extensions of General Relativity were attempted for over
70 years, only recently ghost-free theories of this kind have been
constructed and shown to be free of the ghost instability. This opens
up the possibility exploring new physics beyond General Relativity by
embedding GR in such extended setups. This talk will review the
construction of such theories, their physical content, implications
and limitations.
Reference:
(1) http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.108.041101
(2) See also http://backreaction.blogspot.fi/2013/12/the-comeback-of-massive-gravity.html for a popular description.
