12 research outputs found
Models of Neutrino Masses and Mixings
We review theoretical ideas, problems and implications of neutrino masses and
mixing angles. We give a general discussion of schemes with three light
neutrinos. Several specific examples are analyzed in some detail, particularly
those that can be embedded into grand unified theories.Comment: 44 pages, 2 figures, version accepted for publication on the Focus
Issue on 'Neutrino Physics' edited by F.Halzen, M.Lindner and A. Suzuki, to
be published in New Journal of Physics
Status of global fits to neutrino oscillations
We review the present status of global analyses of neutrino oscillations,
taking into account the most recent neutrino data including the latest KamLAND
and K2K updates presented at Neutrino2004, as well as state-of-the-art solar
and atmospheric neutrino flux calculations. We give the two-neutrino solar +
KamLAND results, as well as two-neutrino atmospheric + K2K oscillation regions,
discussing in each case the robustness of the oscillation interpretation
against departures from the Standard Solar Model and the possible existence of
non-standard neutrino physics. Furthermore, we give the best fit values and
allowed ranges of the three-flavour oscillation parameters from the current
worlds' global neutrino data sample and discuss in detail the status of the
small parameters \alpha \equiv \Dms/\Dma as well as ,
which characterize the strength of CP violating effects in neutrino
oscillations. We also update the degree of rejection of four-neutrino
interpretations of the LSND anomaly in view of the most recent developments.Comment: v6: In the last Appendix we provide updated neutrino oscillation
results which take into account the relevant oscillation data released by the
MINOS and KamLAND collaboration
The ICECUBE prototype string in AMANDA
The Antarctic Muon And Neutrino Detector Array (Amanda) is a high-energy
neutrino telescope. It is a lattice of optical modules (OM) installed in the
clear ice below the South Pole Station. Each OM contains a photomultiplier tube
(PMT) that detects photons of Cherenkov light generated in the ice by muons and
electrons. IceCube is a cubic-kilometer-sized expansion of Amanda currently
being built at the South Pole. In IceCube the PMT signals are digitized already
in the optical modules and transmitted to the surface. A prototype string of 41
OMs equipped with this new all-digital technology was deployed in the Amanda
array in the year 2000. In this paper we describe the technology and
demonstrate that this string serves as a proof of concept for the IceCube
array. Our investigations show that the OM timing accuracy is 5 ns. Atmospheric
muons are detected in excellent agreement with expectations with respect to
both angular distribution and absolute rate
Type II See-Saw at Collider, Lepton Asymmetry and Singlet Scalar Dark Matter.
We propose an extension of the standard model with a B–L global symmetry that is broken softly at the TeV scale. The neutrinos acquire masses through a type-II seesaw while the lepton (L) asymmetry arises in the singlet sector but without B–L-number violation. The model has the virtue that the scale of L-number violation (Λ) giving rise to neutrino masses is independent of the scale of leptogenesis (Λ'). As a result the model can explain neutrino masses, singlet scalar dark matter and leptogenesis at the TeV scale. The stability of the dark matter is ensured by a surviving Z2 symmetry, which could be lifted at the Planck scale, thereby allowing Planck scale suppressed decay of singlet scalar dark matter particles of mass 3 MeV to e+e- pairs in the Galactic halo. The model also predicts a few hundred GeV doubly charged scalar and a long-lived charged fermion, whose decay can be studied at the Large Hadron Collider (LHC) and International Linear Collider (ILC)
Five Years of Searches for Point Sources of Astrophysical Neutrinos with the AMANDA-II Neutrino Telescope.
We report the results of a five-year survey of the northern sky to search for
point sources of high energy neutrinos. The search was performed on the data
collected with the AMANDA-II neutrino telescope in the years 2000 to 2004, with
a live-time of 1001 days. The sample of selected events consists of 4282 upward
going muon tracks with high reconstruction quality and an energy larger than
about 100 GeV. We found no indication of point sources of neutrinos and set 90%
confidence level flux upper limits for an all-sky search and also for a catalog
of 32 selected sources. For the all-sky search, our average (over declination
and right ascension) experimentally observed upper limit
\Phi^{0}=(E/TeV)^\gamma d\Phi/dE to a point source flux of muon and tau
neutrino (detected as muons arising from taus) is \Phi_{\nu_\mu}^{0} +
\Phi_{\nu_\tau}^{0} = 11.1 x 10^{-11} TeV^-1 cm^-2 s^-1, in the energy range
between 1.6 TeV and 2.5 PeV for a flavor ratio \Phi_{\nu_\mu}^{0} /
\Phi_{\nu_\tau}^{0}= 1 and assuming a spectral index \gamma=2. It should be
noticed that this is the first time we set upper limits to the flux of muon and
tau neutrinos. In previous papers we provided muon neutrino upper limits only
neglecting the sensitivity to a signal from tau neutrinos, which improves the
limits by 10% to 16%. The value of the average upper limit presented in this
work corresponds to twice the limit on the muon neutrino flux
\Phi_{\nu_\mu}^{0} = 5.5 \cdot 10^{-11} TeV^-1 cm^-2 s^-1. A stacking analysis
for preselected active galactic nuclei and a search based on the angular
separation of the events were also performed. We report the most stringent flux
upper limits to date, including the results of a detailed assessment of
systematic uncertainties.Comment: 32 pages, 9 figures, submitted to Phys. Rev.
Limits on the muon flux from neutralino annihilations at the center of the Earth with AMANDA
A search has been performed for nearly vertically upgoing neutrino-induced muons with the Antarctic Muon And Neutrino Detector Array (AMANDA), using data taken over the three year period 1997-99. No excess above the expected atmospheric neutrino background has been found. Upper limits at 90% confidence level have been set on the annihilation rate of neutralinos at the center of the Earth, as well as on the muon flux at AMANDA induced by neutrinos created by the annihilation products. © 2006 Elsevier B.V. All rights reserved.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe