Realization of Sneutrino Self-interacting Dark Matter in the Focus Point Supersymmetry

Abstract

The Lightest Supersymmetric Particle (LSP) is generally regarded as higgsino in focus point supersymmetry (SUSY). Under such circumstance it leads to bileptino LSP when the MSSM is extended by $U(1)_{B-L}$ gauge group within the framework of Double Focus Point (DFP) supersymmetry. The bileptino is a copy of higgsino whose partner, bilepton, is used to break $U(1)_{B-L}$ gauge symmetry spontaneously. Such scenario, however, is not favored by direct detection since it leads to unacceptable spin-independent cross section when one requires correct self-scattering cross section. We point out that is not necessarily the case even in the presence of light $Z^{\prime}$. The right-handed sneutrino in this model acts as LSP in most of parameter space for non-vanishing soft trilinear coupling $T_{\eta}$. It is thus consistent of the requirement of DFP SUSY without involving any direct detection issue. The corrected relic abundance could be achieved via sneutrino annihilate into pair of bilepton which also serve as light mediator in Self-Interacting Dark Matter (SIDM). Moreover, stringent constraint comes from CMB anisotropies can be evaded by considering retarded decay of right-handed neutrinos. We further stress the need for a large soft trilinear term $T_{\eta}$ in order to generate desirable self-scattering cross section $\sigma/m_{\tilde\nu_R}$ with moderate Yukawa coupling $Y_{\eta}$. The numerical calculation illustrates that SIDM is reliable in our model from the scales of dwarf galaxy to galaxy cluster.