The halo dark matter (DM) can be captured by the Sun if its final velocity after the collision with a nucleus in the Sun is less than the escape velocity. For self-interacting DM (SIDM), we show that the number of DM trapped inside the Sun still provides significant signals even if the DM-nucleon cross section is negligible. We consider a SIDM model where U (1) gauge symmetry is introduced to account for the DM self-interaction. Such a model naturally leads to isospin violating DM-nucleon interaction, although isospin symmetric interaction is still allowed as a special case.We show that the detection of neutrino signature from DM annihilation in the Sun can probe those SIDM parameter ranges not reachable by direct the detection. Those parameter ranges are either the region with a very small m χ or the region opened up due to isospin violations.

The experiment of Krasznahorkay et al observed the transition of a 8 Be excited state to its ground state and accompanied by an emission of e + e − pair with 17 MeV invariant mass. This 6.8σ anomaly can be fitted by a new light gauge boson. We consider the new particle as a U (1) gauge boson, Z , which plays as a portal linking dark sector and visible sector. In particular, we study the new U (1) gauge symmetry as a hidden or non-hidden group separately. The generic hidden U (1) model, referred to as dark Z model, is excluded by imposing various experimental constraints. On the other hand, a non-hidden Z is allowed due to additional interactions between Z and Standard Model fermions. We also study the implication of the dark matter direct search on such a scenario. We found the search for the DM-nucleon scattering cannot probe the parameter space that is allowed by 8 Be-anomaly for the range of DM mass above 500 MeV. However, the DM-electron scattering for DM between 20 and 50 MeV can test the underlying U (1) portal model using the future Si and Ge detectors with 5e − threshold charges.

We construct a realistic model of CP violation in which CP is broken in the process of dimensional reduction and orbifold compactification from a five dimensional theories with SU (3)×SU (3)×SU (3) gauge symmetry. CP violation is a result of the Hosotani type gauge configuration in the higher dimension.