Speaker
Description
Hidden sectors provide a simple explanation for the origin of dark matter. What is the symmetry of such a hidden sector? One possibility is that the hidden sector is related to the Standard Model gauge group via a discrete or "mirror" symmetry. Such a Mirror Standard Model has three main advantages: 1) It provides a natural dark matter candidate in the lightest stable mirror particle, namely the mirror electron (& positron). 2) The mirror symmetry relates the couplings of the hidden sector to the Standard Model so the theory is highly predictive. 3) The axion, which acts as a portal between the Standard and Mirror sectors, acquires a large mass from mirror strong dynamics, making it more robust to higher dimensional PQ breaking operators which may perturb the axion from its minimum and generate a much larger neutron EDM than observed.
From these features, I will discuss how the dark matter abundance is achieved for freeze-out of mirror electrons of mass near 200 GeV, fixing the mirror electroweak scale near 10^8 GeV and giving rise to a variety of highly predictive signals: (1) primordial gravitational waves from the first-order mirror QCD phase transition occurring at a temperature near 30 GeV, (2) effects on large-scale structure from dark matter self-interactions from mirror QED, (3) dark radiation affecting the cosmic microwave background, and (4) rare kaon decays to axions
