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Brane induced gravi...
Brane induced gravity, its ghost and the cosmological constant problem
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- Hassan, S. Fawad (författare)
- Stockholms universitet,Fysikum,Oskar Klein-centrum för kosmopartikelfysik (OKC)
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Hofmann, Stefan (författare)
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- von Strauss, Mikael, 1978- (författare)
- Stockholms universitet,Fysikum,Oskar Klein-centrum för kosmopartikelfysik (OKC)
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(creator_code:org_t)
- 2011-01-20
- 2011
- Engelska.
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :1, s. 020-
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Abstract
Ämnesord
Stäng
- 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.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- modified gravity
- cosmological applications of theories with extra dimensions
- teoretisk fysik
- Theoretical Physics
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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