http://arxiv.org/abs/2109.13287
We have recently proposed a simple relativistic theory which reduces to Modified Newtonian Dynamics (MOND) for the weak-field quasistatic situations applied to galaxies, and to cosmological behaviour as in the $\Lambda$CDM model, yielding a realistic cosmology in line with observations. A key requirement of any such model is that Minkowski space is stable against linear perturbations. We expand the theory action to 2nd order in perturbations on a Minkowski background and show that it leads to healthy dispersion relations involving propagating massive modes in the vector and the scalar sector. We use Hamiltonian methods to eliminate constraints present, demonstrate that the massive modes have positive Hamiltonian and show that a non-propagating mode with a linear time dependence may have negative Hamiltonian for wavenumbers $k< k_$ and positive otherwise. The scale $k_$ is estimated to be around $\lesssim \mathrm{Mpc}^{-1}$ so that the low momenta instability may only play a role on cosmological scales.
C. Skordis and T. Zlosnik
Wed, 29 Sep 21
47/78
Comments: N/A
You must be logged in to post a comment.