Determining the Flavour Content of the Low-Energy Solar Neutrino Flux

We study the sensitivity of the HELLAZ and Borexino solar neutrino experiments on discriminating the neutrino species nu_e, anti-nu_e, nu_{mu,tau}, anti-nu_{mu,tau}, and nu_{sterile} using the difference in the recoil electron kinetic energy spectra in elastic neutrino-electron scattering. We find that one can observe a non-vanishing nu_{mu,tau} component in the solar neutrino flux, especially when the nu_e survival probability is low. Also, if the data turn out to be consistent with nu_e nu_{mu,tau} oscillations, an anti-nu_e component can be excluded effectively.Comment: 24 pages, 7 figure

Fake Dark Matter at Colliders

If the dark matter (DM) consists of a weakly interacting massive particle (WIMP), it can be produced and studied at future collider experiments like those at the LHC. The production of collider-stable WIMPs is characterized by hard scattering events with large missing transverse energy. Here we point out that the discovery of this well-characterized DM signal may turn out to be a red herring. We explore an alternative explanation -- fake dark matter -- where the only sources of missing transverse energy are standard model neutrinos. We present examples of such models, focusing on supersymmetric models with R-parity violation. We also briefly discuss means of differentiating fake dark matter from the production of new collider-stable particles.Comment: 11 pages, 3 figures, revtex; references adde

What would it take to determine the neutrino mass hierarchy if θ13\theta_{13} were too small?

We discuss the experimental requirements for a mass hierarchy measurement for $\theta_{13}=0$ using muon neutrino disappearance. We find that a specially optimized neutrino factory at $L \simeq 6 \,000 \, \mathrm{km}$ could do this measurement using extreme luminosities. In particular, we do not require charge identification for this purpose. In order to measure the mass hierarchy for more adequate luminosities, we explore the capabilities of low energy narrow band off-axis beams, which have relatively more events at low energies. We find that, in this case, the energy resolution of the detector quickly becomes the limiting factor of the measurement, and significantly affects the baseline optimization for determining the mass hierarchy.Comment: 22 pages, 10 color figure