2019/12/31 by Shun Arai, Purnendu Karmakar, Atsushi Nishizawa
Physics and Astronomy · #gr-qc #astro-ph.CO #hep-th
paper · pdf · doi:10.1103/physrevd.102.024003
published as Phys. Rev. D 102, 024003 (2020) · 43 pages, 20 figures, updated to the PRD accepted version
arxiv created 2020/10/21 · arxiv updated 2020/10/22
We investigate the parameter distributions of the viable generalized scalar-tensor theory with conventional dust matter after GW170817 in a model-independent way. We numerically construct the models by computing the time evolution of a scalar field, which leads to a positive definite second-order Hamiltonian and are consistent with the observed Hubble parameter. We show the model parameter distributions in the degenerate higher-order scalar-tensor (DHOST) theory, and its popular subclasses, e.g., Horndeski and GLPV theories, etc.. We find that 1) the Planck mass run rate, αM, is insensitive to distinguish the theories. 2) the kinetic-braiding parameter, αB, clearly discriminates the models from those of the Horndeski theory, 3) the parameters for the higher-order theories, αH and β1, are relatively smaller in magnitude (by several factors) than αM and αB, but can still be used for discriminating the theories except for the GLPV theory. Based on the above three facts, we propose a minimal set of parameters that sensibly distinguishes the subclasses of DHOST theories, (αM, αB-αM/2, β1).