Robustness of the cosmological constant damping mechanism through matter eras

Abstract A dynamical resolution to the cosmological constant fine-tuning problem has been previously put forward, based on a gravitational scalar–tensor theory possessing de Sitter attractor solutions characterized by small Hubble expansion rate, irrespective of an initially large vacuum energy. We show that technically natural subregion parameter space yields evolution through radiation- and matter-dominated eras is essentially indistinguishable from predicted general relativity. Similarly, proposed model automatically satisfies observational constraints fifth force mediated new scalar degree freedom.