2010/09/30 by Anzhong Wang, Qiang Wu · 1 citation
Physics and Astronomy · #hep-th #astro-ph.CO #gr-qc #hep-ph
paper · pdf · doi:10.1103/physrevd.83.044025
published as Phys.Rev.D83:044025,2011 · Some points regarding to strong coupling are further clarified, and typos corrected. revtex4, 9 figures. Version to appear in Physical Reviews D
arxiv created 2011/01/21 · arxiv updated 2011/02/18
In this paper, we consider two different issues, stability and strong coupling, raised lately in the newly-proposed Horava-Lifshitz (HL) theory of quantum gravity with projectability condition. We find that all the scalar modes are stable in the de Sitter background, due to two different kinds of effects, one from high-order derivatives of the spacetime curvature, and the other from the exponential expansion of the de Sitter space. Combining these effects properly, one can make the instability found in the Minkowski background never appear even for small-scale modes, provided that the IR limit is sufficiently closed to the relativistic fixed point. At the fixed point, all the modes become stabilized. We also show that the instability of Minkowski spacetime can be cured by introducing mass to the spin-0 graviton. The strong coupling problem is investigated following the effective field theory approach, and found that it cannot be cured by the Blas-Pujolas-Sibiryakov mechanism, initially designed for the case without projectability condition, but might be circumvented by the Vainshtein mechanism, due to the non-linear effects. In fact, we construct a class of exact solutions, and show explicitly that it reduces smoothly to the de Sitter spacetime in the relativistic limit.