APEC Seminar (Astronomy - Particle Physics - Experimental Physics - Cosmology)

Speaker: Bum-Hoon Lee (Sogang University)
Title: Dilatonic Einstein Gauss-Bonnet Cosmology and constraints from the WIMP Dark Matter
Date (JST): Thu, Sep 28, 2023, 13:30 - 15:00
Place: Seminar Room A
Abstract: We explain the Cosmological implications of dilatonic Einstein Gauss-Bonnet (dEGB) gravity, where the Gauss–Bonnet term is non–minimally coupled. The potential for a scalar field will be put to zero mainly for simplicity. We then use the Weakly Interacting Massive Particle (WIMP) thermal decoupling scenario to probe it. The model parameters will be constrained when the ensuing modified cosmological scenario drives the WIMP annihilation cross section beyond the present bounds from DM indirect detection searches. For the class of solutions that comply with WIMP indirect detection bounds, we find that dEGB typically plays a mitigating role on the scalar field dynamics at high temperature, slowing down the speed of its evolution and reducing the enhancement of the Hubble constant compared to its standard value. For such solutions, we observe that the corresponding boundary conditions at high temperature correspond asymptotically to a vanishing deceleration parameter q, so that the effect of dEGB is to add an accelerating term that exactly cancels the deceleration predicted by General Relativity. The bounds from WIMP indirect detection are nicely complementary to late-time constraints from compact binary mergers. This suggests that it could be interesting to use other Early Cosmology processes to probe the dEGB scenario.

Remarks: Seminar Room A + Zoom