A CoGeNT confirmation of the DAMA signal

The CoGeNT collaboration has recently reported a rising low energy spectrum in their ultra low noise germanium detector. This is particularly interesting as the energy range probed by CoGeNT overlaps with the energy region in which DAMA has observed their annual modulation signal. We show that the mirror dark matter candidate can simultaneously explain both the DAMA annual modulation signal and the rising low energy spectrum observed by CoGeNT. This constitutes a model dependent confirmation of the DAMA signal and adds weight to the mirror dark matter paradigm.Comment: About 8 pages, expanded and update

Dissipative dark matter halos: The steady state solution

Dissipative dark matter, where dark matter particle properties closely resemble familiar baryonic matter, is considered. Mirror dark matter, which arises from an isomorphic hidden sector, is a specific and theoretically constrained scenario. Other possibilities include models with more generic hidden sectors that contain massless dark photons (unbroken $U(1)$ gauge interactions). Such dark matter not only features dissipative cooling processes, but is also assumed to have nontrivial heating sourced by ordinary supernovae (facilitated by the kinetic mixing interaction). The dynamics of dissipative dark matter halos around rotationally supported galaxies, influenced by heating as well as cooling processes, can be modelled by fluid equations. For a sufficiently isolated galaxy with stable star formation rate, the dissipative dark matter halos are expected to evolve to a steady state configuration which is in hydrostatic equilibrium and where heating and cooling rates locally balance. Here, we take into account the major cooling and heating processes, and numerically solve for the steady state solution under the assumptions of spherical symmetry, negligible dark magnetic fields, and that supernova sourced energy is transported to the halo via dark radiation. For the parameters considered, and assumptions made, we were unable to find a physically realistic solution for the constrained case of mirror dark matter halos. Halo cooling generally exceeds heating at realistic halo mass densities. This problem can be rectified in more generic dissipative dark matter models, and we discuss a specific example in some detail.Comment: 34 page

Some comments on Super-Kamiokande's multi-ring analysis

The super-Kamiokande collaboration have used multi-ring events to discriminate between the $\nu_\mu --> \nu_\tau$ and $\nu_\mu --> \nu_s$ solutions to the atmospheric neutrino anomaly. We show that the effect of systematic uncertainties in cross sections are so significant that the usefulness of multi-ring data to distinguish between these two solutions is doubtful.Comment: About 8 pages lon

Are four neutrino models ruled out?

We show explicitly that four neutrino models of the 2+2 variety still provide an acceptable global fit to the solar, atmospheric and LSND neutrino data. The goodness of fit, defined in the usual way, is found to be 0.26 for the simplest such model. That is, we find that there is a 26% probability of obtaining a worse global fit to the neutrino data We also make some specific comments on the paper, ``Ruling out four-neutrino oscillation interpretations of the LSND anomaly'' [hep-ph/0207157], and explain why they reached drastically different conclusions.Comment: about 4 page