The Photometric Period of the Cataclysmic Variable HV Andromedae

We present four nights of time-resolved photometry of the cataclysmic variable star HV And. Our time series analysis has revealed a prominent period at 3.368 +/- 0.060 hours, as well as some low frequency power. We interpret this signal, from saw-tooth waves in the light curve, as evidence of superhumps in HV And.Comment: 7 pages, 3 figures; accepted for publication in New Astronom

Phenomenology of Multi-W Processes in Cosmic Rays

We report on a study of the potential of various cosmic ray physics experiments to search for Standard Model processes involving the nonperturbative production of O(30) weak gauge bosons. Whereas present and near-future experiments are insensitive to proton-induced processes, neutrino-induced processes give rise to promising signatures and rates in AMANDA, DUMAND, MACRO and NESTOR provided that a cosmic neutrino flux exists at levels suggested by recent models of active galactic nuclei. The Fly's Eye currently constrains the largest region of parameter space characterizing multi-W phenomena.Comment: (Invited talk presented by A. Ringwald at 17th Johns Hopkins Workshop on Current Problems in Particle Theory, Particles and the Universe, July 30-August 1, 1993, Budapest, Hungary), 16 pages (LaTeX) + 10 uuencoded PostScript figures, CERN-TH.7005/93, UCLA/93/TEP/3

Multiple Muons From Neutrino-Initiated Multi-W(Z) Production

Current underground detectors can search for multiple muons from multi-W(Z) production initiated by ultrahigh energy neutrinos from active galactic nuclei. O($\mu$b) cross sections give rise to downward going muon bundles whose features differ from those of atmospheric muon bundles.Comment: (presented at 23rd Int. Cosmic Ray Conf., July 21-30 1993, Calgary, Canada), 5 pages (LaTeX) + 2 uuencoded PostScript figures, UCLA/93/TEP/3

Frontiers in Cosmic Rays

This rapporteur review covers selected results presented in the Parallel Session HEA2 (High Energy Astrophysics 2) of the 10th Marcel Grossmann Meeting on General Relativity, held in Rio de Janeiro, Brazil, July 2003. The subtopics are: ultra high energy cosmic ray anisotropies, the possible connection of these energetic particles with powerful gamma ray bursts, and new exciting scenarios with a strong neutrino-nucleon interaction in the atmosphere.Comment: 20 pages, 8 eps figures. Rapporteur Review of the Parallel Session: High Energy Astrophysics 2; to appear in Proceedings of the Tenth Marcel Grossmann Meeting on General Relativity, edited by M. Novello, S. Perez-Bergliaffa and R. Ruffini, World Scientific, Singapore, 2005. (MGX Rio de Janeiro, Brazil, July, 2003

Strongly interacting neutrinos as the highest energy cosmic rays

We show that all features of the ultrahigh energy cosmic ray spectrum from 10^{17} eV to 10^{21} eV can be described with a simple power-like injection spectrum of protons under the assumption that the neutrino-nucleon cross-section is significantly enhanced at center of mass energies above \approx 100 TeV. In our scenario, the cosmogenic neutrinos produced during the propagation of protons through the cosmic microwave background initiate air showers in the atmosphere, just as the protons. The total air shower spectrum induced by protons and neutrinos shows excellent agreement with the observations. A particular possibility for a large neutrino-nucleon cross-section exists within the Standard Model through electroweak instanton-induced processes.Comment: 8 pages, 4 figures, talk given at Beyond the Desert '03, Castle Ringberg, 9-14 June, 200

Dark Matter and Dark Forces from a supersymmetric hidden sector

We show that supersymmetric "Dark Force" models with gravity mediation are viable. To this end, we analyse a simple string-inspired supersymmetric hidden sector model that interacts with the visible sector via kinetic mixing of a light Abelian gauge boson with the hypercharge. We include all induced interactions with the visible sector such as neutralino mass mixing and the Higgs portal term. We perform a detailed parameter space scan comparing the produced dark matter relic abundance and direct detection cross sections to current experiments.Comment: 40 pages, 11 figures comprising 21 plots. 4Mb total size. v2: figures and references updated; typos removed; some extra explanations added. Matches version published in PR

Neutrino Models of Dark Energy

I consider a scenario proposed by Fardon, Nelson and Weiner where dark energy and neutrinos are connected. As a result, neutrino masses are not constant but depend on the neutrino number density. By examining the full equation of state for the dark sector, I show that in this scenario the dark energy is equivalent to having a cosmological constant, but one that "runs" as the neutrino mass changes with temperature. Two examples are examined that illustrate the principal feautures of the dark sector of this scenario. In particular, the cosmological constant is seen to be negligible for most of the evolution of the Universe, becoming inportant only when neutrinos become non-relativistic. Some speculations on features of this scenario which might be present in a more realistic theory are also presented.Comment: 12 pages, 6 figures. Added comments on why FNW scenario always leads to a running cosmological constant and a few references. To be published in Phys. Rev.