Theory HEP Seminar

Ultralight Dark Matter from A(LPs) to U(LPs)

Evan McDonough

University of Winnipeg

Axions and axion-like particles (ALPs) are a prominent dark matter candidate, but not are not the only game (sub-eV DM candidate) in town. I will review the general class of models referred to as Ultra-Light Dark Matter (ULDM), with a focus on DM arising from composite states in a strongly coupled gauge theory: ULPs (Ultra-Light Pions). Accounting for the full spectrum of the theory, this scenario simultaneously realizes the ultra-light and superheavy (“WIMPzilla”) dark matter paradigms, connected by the confinement scale of the dark QCD. Unlike conventional axions, the DM in this case can be charged, with a mass splitting between the charged and neutral pions. The dark baryons, produced via gravitational particle production or via freeze-in, provide an additional contribution to the dark matter density. Dark matter halos in this context are generically an admixture of the three pions and heavy baryons. I will discuss the observables of the ULP-Wimpzilla scenario and of ULDM models more generally, and time permitting, realization of ULPs in string theory, and connection to the Hubble Tension.