Naslov
Nonderivative Modified Gravity: a Classification

Autori
Comelli, Denis ; Nesti, Fabrizio ; Pilo, Luigi

Izvornik
Journal of Cosmology and Astroparticle Physics (1475-7516) 11 (2014); 018-1

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
modified gravity ; gravity ; cosmological perturbation theory

Sažetak
We analyze the theories of gravity modified by a generic nonderivative potential built from the metric, under the minimal requirement of unbroken spatial rotations. Using the canonical analysis, we classify the potentials V according to the number of degrees of freedom (DoF) that propagate at the nonperturbative level. We then compare the nonperturbative results with the perturbative DoF propagating around Minkowski and FRW backgrounds. A generic V implies 6 propagating DoF at the non- perturbative level, with a ghost on Minkowski background. There exist potentials which propagate 5 DoF, as already studied in previous works. Here, no V with unbroken rotational invariance admitting 4 DoF is found. Theories with 3 DoF turn out to be strongly coupled on Minkowski background. Finally, potentials with only the 2 DoF of a massive graviton exist. Their effect on cosmology is simply equivalent to a cosmological constant. Potentials with 2 or 5 DoF and explicit time dependence appear to be a further viable possibility.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

POVEZANOST RADA