IBS CTPU-CGA 2024 Summer School and Workshop for Particle Physics and Cosmology in Korea

Freeze-in Inelastic Dirac Dark Matter and H0 tension

23 Jul 2024, 16:10

25m

Muju Deogyusan Resort

Presentations

Speaker

Mr Wonsub Cho (SKKU)

Description

The discrepancy in the estimation of the Hubble constant, as measured by the local distance ladder and the Cosmic Microwave Background (CMB) observations, has become a significant concern, reaching a $4\sigma$ to $6\sigma$ level of significance. In this study, we investigate a particle physics model featuring an inelastic Dirac dark matter framework with a gauged $U(1{)}_D$ symmetry, aimed at mitigating this tension in a cosmologically consistent manner while maintaining feeble coupling between the dark and visible sectors. Our model proposes the production of dark sector particles through a freeze-in mechanism, with the two sectors retaining distinct temperatures due to minimal kinetic mixing. Leveraging the presence of a light mediator, the dark matter particles undergo late-stage annihilation into these mediators via resonantly enhanced Sommerfeld cross-sections. Subsequently, these mediators annihilate into self-interacting dark radiations, selectively influencing the dynamics during the CMB era without perturbing Big Bang Nucleosynthesis (BBN), thus offering a dual solution by alleviating both the Hubble constant ($H_0$) and ${\sigma }_8$ tensions concurrently.