1,115 research outputs found
Dark Matter Detection With Electron Neutrinos in Liquid Scintillation Detectors
We consider the prospects for liquid scintillation experiments (with a focus
on KamLAND) to detect the flux of electron neutrinos arising from dark matter
annihilation in the core of the sun. We show that, with data already taken,
KamLAND can provide the greatest sensitivity to the dark matter-proton
spin-dependent scattering cross-section for dark matter lighter than 20 GeV. It
is also possible to probe the dark matter-nucleon spin-independent scattering
cross-section for isospin-violating dark matter lighter than 10 GeV. KamLAND
can thus potentially confirm the dark matter interpretation of the DAMA and
CoGeNT signals, utilizing data already taken.Comment: 5 pages, 4 figures, PDFLaTeX; v2: references added, figures updated,
more detailed comparison of liquid scintillation and water Cerenkov detectors
(journal version
Extra dimensions and Strong Neutrino-Nucleon interactions above eV : Breaking the GZK Barrier
Cosmic ray events above eV are on the verge of confronting
fundamental particle physics. The neutrino is the only candidate primary among
established particles capable of crossing 100 Mpc intergalactic distances
unimpeded. The magnitude of cross sections indicated by events, plus
consistency with the Standard Model at low-energy, point to new physics of
massive spin-2 exchange. In models based on extra dimensions, we find that the
cross section rises to typical hadronic values of between 1 and 100 mb
at energies above eV. Our calculations take into account constraints
of unitarity. We conclude that air-showers observed with energies above
eV are consistent with neutrino primaries and extra-dimension models.
An {\it upper bound} of 1-10 TeV on the mass scale at which graviton exchange
becomes strong in current Kaluza-Klein models follows.Comment: 14 pages, 2 figures, minor change
Light Dark Matter Detection Prospects at Neutrino Experiments
We consider the prospects for the detection of relatively light dark matter
through direct annihilation to neutrinos. We specifically focus on the
detection possibilities of water Cherenkov and liquid scintillator neutrino
detection devices. We find in particular that liquid scintillator detectors may
potentially provide excellent detection prospects for dark matter in the 4-10
GeV mass range. These experiments can provide excellent corroborative checks of
the DAMA/LIBRA annual modulation signal, but may yield results for low mass
dark matter in any case. We identify important tests of the ratio of electron
to muon neutrino events (and neutrino versus anti-neutrino events), which
discriminate against background atmospheric neutrinos. In addition, the
fraction of events which arise from muon neutrinos or anti-neutrinos (
and ) can potentially yield information about the branching
fractions of hypothetical dark matter annihilations into different neutrino
flavors. These results apply to neutrinos from secondary and tertiary decays as
well, but will suffer from decreased detectability.Comment: 13 pages, 2 figures, pdflatex, references, one figure and comments on
electron neutrino bounds and on spin-dependent scattering limits added.
Figures updated
Enhanced signal of astrophysical tau neutrinos propagating through Earth
Earth absorbs \nue and \numu of energies above about 100 TeV. As is
well-known, although \nutau will also disappear through charged-current
interactions, the \nutau flux will be regenerated by prompt tau decays. We
show that this process also produces relatively large fluxes of secondary
\nube and \nubmu, greatly enhancing the detectability of the initial
\nutau. This is particularly important because at these energies \nutau is
a significant fraction of the expected astrophysical neutrino flux, and only a
tiny portion of the atmospheric neutrino flux.Comment: Four pages, two inline figure
Neutrino Decay and Atmospheric Neutrinos
We reconsider neutrino decay as an explanation for atmospheric neutrino
observations. We show that if the mass-difference relevant to the two mixed
states \nu_\mu and \nu_\tau is very small (< 10^{-4} eV^2), then a very good
fit to the observations can be obtained with decay of a component of \nu_\mu to
a sterile neutrino and a Majoron. We discuss how the K2K and MINOS
long-baseline experiments can distinguish the decay and oscillation scenarios.Comment: 9 pages, Revtex, uses epsf.sty, 3 postscript figures. Additions and
corrections to references, minor changes in the text and to some number
End of the cosmic neutrino energy spectrum
There may be a high-energy cutoff of neutrino events in IceCube data. In
particular, IceCube does not observe either continuum events above 2 PeV, or
the Standard Model Glashow-resonance events expected at 6.3 PeV. There are also
no higher energy neutrino signatures in the ANITA and Auger experiments. This
absence of high-energy neutrino events motivates a fundamental restriction on
neutrino energies above a few PeV. We postulate a simple scenario to terminate
the neutrino spectrum that is Lorentz-invariance violating, but with a limiting
neutrino velocity that is always smaller than the speed of light. If the
limiting velocity of the neutrino applies also to its associated charged
lepton, then a significant consequence is that the two-body decay modes of the
charged pion are forbidden above two times the maximum neutrino energy, while
the radiative decay modes are suppressed at higher energies. Such stabilized
pions may serve as cosmic ray primaries.Comment: 6 pages. Version to appear in PL
- …