Unified TeV Scale Picture of Baryogenesis and Dark Matter

We present a simple extension of MSSM which provides a unified picture of cosmological baryon asymmetry and dark matter. Our model introduces a gauge singlet field $N$ and a color triplet field $X$ which couple to the right--handed quark fields. The out--of equilibrium decay of the Majorana fermion $N$ mediated by the exchange of the scalar field $X$ generates adequate baryon asymmetry for $M_N \sim 100$ GeV and $M_X \sim$ TeV. The scalar partner of $N$ (denoted $\tilde{N}_1$) is naturally the lightest SUSY particle as it has no gauge interactions and plays the role of dark matter. $\tilde{N}_1$ annihilates into quarks efficiently in the early universe via the exchange of the fermionic $\tilde{X}$ field. The model is experimentally testable in (i) neutron--antineutron oscillations with a transition time estimated to be around $10^{10}$ sec, (ii) discovery of colored particles $X$ at LHC with mass of order TeV, and (iii) direct dark matter detection with a predicted cross section in the observable range.Comment: 10 pages, one reference updated. Version to appear in Phys. Rev. Let

Sterile neutrino decay as a common origin for LSND/MiniBooNe and T2K excess events

We point out that the excess of electron-like neutrino events recently observed by the T2K collaboration may have a common origin with the similar excess events previously reported by the LSND and MiniBooNE experiments and interpreted as a signal from the radiative decays of a sterile neutrino \nu_h with the mass around 50 MeV produced in muon neutrino neutral current (NC) interactions. In this work we assumed that the \nu_h can also be produced in tau neutrino NC reactions.Comment: 5 pages, 5 figures. Revised version accepted by PRD (Rapid Comm.) after referee's suggestions. Fig.1 added for illustratio