Speaker
Description
While direct and indirect detection experiments have yet to find dark matter interacting with standard model particles, cosmological probes provide a complementary approach for exploring phenomenological dark matter-baryon scattering models. These models have two parameters vulnerable to prior volume effects, namely the scattering cross section and the fraction of dark matter that interacts with standard model particles. As either parameter approaches its standard model value, the prior volume becomes unconstrained, potentially biasing a Bayesian posterior distribution towards that region. To avoid the use of priors, we take a frequentist approach using profile likelihoods to constrain dark matter-proton scattering using observations of the cosmic microwave background. We find no evidence of interactions between dark matter and protons, which is consistent with the Bayesian analysis. For different fractions of dark matter interacting with protons, we obtain upper limits on the interaction cross section as a function of dark matter particle mass, which we compare to the Bayesian limits.
