Realization of sneutrino self-interacting dark matter in the focus point supersymmetry.

The lightest supersymmetric particle (LSP) is generally regarded as a Higgsino in focus point supersymmetry (SUSY). Under such a circumstance, it leads to a bileptino LSP when the minimal supersymmetric Standard Model (MSSM) is extended by the U(1)B-L gauge group within the framework of double focus point (DFP) supersymmetry. The bileptino is a copy of a Higgsino whose partner, the bilepton, is used to break U(1)B-L gauge symmetry spontaneously. Such a scenario, however, is not favored by direct detection since it leads to an unacceptable spin-independent cross section when one requires a correct self-scattering cross section. We point out that is not necessarily the case even in the presence of light Z′. The right-handed sneutrino in this model acts as the LSP in most of the parameter space for nonvanishing soft trilinear coupling Tη. It is thus consistent with the requirement of DFP SUSY without involving any direct detection issue. The corrected relic abundance could be achieved via a sneutrino annihilating into a pair of bileptons, which also serve as a light mediator in self-interacting dark matter (SIDM). Moreover, the stringent constraint that comes from cosmic microwave background anisotropies can be evaded by considering the retarded decay of right-handed neutrinos. We further stress the need for a large soft trilinear term Tη in order to generate a desirable self-scattering cross section σ/m˜νR with moderate Yukawa coupling Yη. The numerical calculation illustrates that SIDM is reliable in our model from the scales of a dwarf galaxy to a galaxy cluster. [ABSTRACT FROM AUTHOR]