Brane induced gravity, its ghost and the cosmological constant problem
2011 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, no 1, 020- p.Article in journal (Refereed) Published
Brane Induced Gravity is regarded as a promising framework for addressing the cosmological constant problem, but it also suffers from a ghost instability for parameter values that make it phenomenologically viable. We carry out a detailed analysis of codimension > 2 models employing gauge invariant variables in a flat background approximation. It is argued that using instead a curved background sourced by the brane would not resolve the ghost issue, unless a very specific condition is satisfied (if satisfiable at all). As for other properties of the model, from an explicit analysis of the 4-dimensional graviton propagator we extract a mass, a decay width and a momentum dependent modification of the gravitational coupling for the spin 2 mode. In the flat space approximation, the mass of the problematic spin 0 ghost is instrumental in filtering out a brane cosmological constant. The mass replaces a background curvature that would have had the same function. The optical theorem is used to demonstrate the suppression of graviton leakage into the uncompactified bulk. Then, we derive the 4-dimensional effective action for gravity and show that general covariance is spontaneously broken by the bulk-brane setup. This provides a natural realization of the gravitational Higgs mechanism. We also show that the addition of extrinsic curvature dependent terms has no bearing on linearized brane gravity.
Place, publisher, year, edition, pages
2011. no 1, 020- p.
modified gravity, cosmological applications of theories with extra dimensions
Astronomy, Astrophysics and Cosmology
Research subject Theoretical Physics
IdentifiersURN: urn:nbn:se:su:diva-68376DOI: 10.1088/1475-7516/2011/01/020ISI: 000286802900020OAI: oai:DiVA.org:su-68376DiVA: diva2:472813