Electroweak Baryogenesis and Dark Matter via a Pseudoscalar vs. Scalar

We study the electroweak baryogenesis in a fermionic dark matter scenario with a (pseudo)scalar being the mediator in the Higgs portal. It is discussed that the electroweak phase transition turns to be first-order after taking into account the role of the (pseudo)scalar in the thermal effective potential in our extended standard model. Imposing the relic density constraint from the WMAP/Planck and the bounds from the direct detection experiments XENON100/LUX, we show that the dark matter scenario with a scalar mediator is hardly capable of explaining the baryogenesis while the same model with a pseudoscalar mediator is able to explain the baryon asymmetry. For the latter, we constrain more the model with {\it Fermi}-LAT upper limit on dark matter annihilation into $b\bar b$ and $\tau^+\tau^-$. The allowed dark matter mass that leads to correct relic abundance, renders the electroweak phase transition strongly first-order, and respects the {\it Fermi}-LAT limit, will be in the range $110-320$ GeV. The exotic and invisible Higgs decay bounds and the mono-jet search limit at the LHC do not affect the viable space of parameters.Comment: 15 pages, 4 figures. Fermi-LAT constraint on DM DM to b\bar, tau^+ tau^- in the model was imposed. The range of the mediator mass was shown in a figure. Published in JHE

Intense Neutrino Beams and Leptonic CP Violation

Effects of the Leptonic CP violating phase,\delta, on 3 generation neutrino oscillation rates and asymmetries are discussed. A figure of merit argument is used to show that our ability to measure the phase \delta is rather insensitive to the value of \theta_{13} (for \sin^22\theta_{13}\gsim0.01) as well as the detector distance (for very long oscillation baselines). Using a study of \nu_\mu\to\nu_e oscillations for BNL-Homestake (2540 km) we show that a conventional horn focused wide band neutrino beam generated by an intense 1-2 MW proton source combined with a very large water Cherenkov detector (250-500 kton) should be able to determine \delta to about \pm 15^\circ$in 5\times 10^7sec of running. In addition, such an effort would also measure the other oscillation parameters (\theta_{ij},\Delta m^2_{ij}) with high precision. Similar findings apply to a Fermilab-Homestake (1280 km)baseline. We also briefly discuss features of Superbeams, Neutrino Factories and Beta-Beams.Comment: 7 pages,$ Figures, to be published in Neutrino2006 Proceeding