UC Berkeley

© 2020, The Author(s). An exact parity replicates the Standard Model giving a Mirror Standard Model, SM ↔ SM′. This “Higgs Parity” and the mirror electroweak symmetry are spontaneously broken by the mirror Higgs, 〈H′〉 = v′ ≫ 〈H〉, yielding the Standard Model Higgs as a Pseudo-Nambu-Goldstone Boson of an approximate SU (4) symmetry, with a quartic coupling λSM(v′) ∼ 10−3. Mirror electromagnetism is unbroken and dark matter is composed of e′ and e¯ ′. Direct detection may be possible via the kinetic mixing portal, and in unified theories this rate is correlated with the proton decay rate. With a high reheat temperature after inflation, the et dark matter abundance is determined by freeze-out followed by dilution from decays of mirror neutrinos, ν′→ ℓH. Remarkably, this requires v′∼ (108–1010) GeV, predicting a Higgs mass of 123 ± 3 GeV at 1σ and a Standard Model neutrino mass of (10−2–10−1) eV, consistent with observed neutrino masses. The mirror QCD sector exhibits a first order phase transition producing gravitational waves that may be detected by future observations. Mirror glueballs decay to mirror photons giving dark radiation with ∆Neff∼ 0.03–0.4. With a low reheat temperature after inflation, the e′ dark matter abundance is determined by freeze-in from the SM sector by either the Higgs or kinetic mixing portal.