Programme

O.2 -- Oral, VCTP-51

Date: Monday, 3 August 2026

Time: 11:30 - 11:50

Freeze-in Production of Non-Abelian Millicharged Vector Dark Matter

Van Que Tran (1) and Tzu-Chiang Yuan (2)

(1) National Center for Theoretical Sciences, National Taiwan University, Taiwan and Phenikaa Institute for Advanced Study, Phenikaa University, Vietnam; (2) Institute of Physics, Academia Sinica, Taiwan

We present the first predictive realization of vector freeze-in dark matter from a hidden non-Abelian gauge sector, spontaneously broken to a residual $U(1)$ with a massless dark photon mediator. A massive dark vector particle-antiparticle pair acquires small millicharges via a dimension-five kinetic mixing operator that induces a dimension-four mixing term with effective coefficient $\epsilon$, and interacts through the hidden gauge coupling $g_D$, linking it weakly to the Standard Model. Solving the relic abundance with a two-temperature Boltzmann evolution including plasmon decays, we find a wide region of parameter space that reproduces the observed density while satisfying astrophysical and cosmological bounds. This minimal framework links non-Abelian vector dynamics, long-range dark forces, and dark matter, and can be testable with upcoming sub-GeV dark matter direct-detection experiments.

Presenter: Tran Van Que