Graviton Emission into Non-Z_2 Symmetric Brane World Spacetimes
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS(2008)
摘要
The equations for the evolution of a homogeneous brane world that emits gravitons at early times, and into a non-Z(2) symmetric bulk, are derived using an AdS - Vaidya spacetime approximation. The behaviour of the black hole mass parameters either side of the brane is analysed, and it is found that in general graviton emission leads to a decrease in the non-Z(2) symmetry. However, the behaviour of the dark radiation term in the Friedmann equation is more complex: it is shown that this term can increase or decrease due to the non-Z(2) symmetry, and can become negative in some cases, leading to H = 0 and the brane universe collapsing. Constraints on the initial (non-zero) sizes of the mass parameters are therefore derived.
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关键词
extra dimensions,cosmology with extra dimensions,cosmology of theories beyond the SM
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