10 research outputs found
Low energy neutrino astronomy with the large liquid scintillation detector LENA
The detection of low energy neutrinos in a large scintillation detector may
provide further important information on astrophysical processes as supernova
physics, solar physics and elementary particle physics as well as geophysics.
In this contribution, a new project for Low Energy Neutrino Astronomy (LENA)
consisting of a 50kt scintillation detector is presented.Comment: Proccedings of the International School of Nuclear Physics, Neutrinos
in Cosmology, in Astro, Particle and Nuclear Physics, Erice (SICILY) 16 - 24
Sept. 200
Reactor Neutrino Experiments with a Large Liquid Scintillator Detector
We discuss several new ideas for reactor neutrino oscillation experiments
with a Large Liquid Scintillator Detector. We consider two different scenarios
for a measurement of the small mixing angle with a mobile
source: a nuclear-powered ship, such as a submarine or an
icebreaker, and a land-based scenario with a mobile reactor. The former setup
can achieve a sensitivity to at the 90%
confidence level, while the latter performs only slightly better than Double
Chooz. Furthermore, we study the precision that can be achieved for the solar
parameters, and , with a mobile reactor
and with a conventional power station. With the mobile reactor, a precision
slightly better than from current global fit data is possible, while with a
power reactor, the accuracy can be reduced to less than 1%. Such a precision is
crucial for testing theoretical models, e.g. quark-lepton complementarity.Comment: 18 pages, 3 figures, 2 tables, revised version, to appear in JHEP,
Fig. 1 extended, Formula added, minor changes, results unchange
U_{PMNS} = U_ell^dagger U_nu
We consider corrections to vanishing U_{e3} and maximal atmospheric neutrino
mixing originating from the relation U = U_ell^dagger U_nu, where U is the PMNS
mixing matrix and U_ell (U_nu) is associated with the diagonalization of the
charged lepton (neutrino) mass matrix. We assume that in the limit of U_ell or
U_nu being the unit matrix, one has U_{e3} = 0 and theta_{23} = pi/4, while the
solar neutrino mixing angle is a free parameter. Well-known special cases of
the indicated scenario are the bimaximal and tri-bimaximal mixing schemes. If
U_{e3} \neq 0 and theta_{23} \neq pi/4 due to corrections from the charged
leptons, |U_{e3}| can be sizable (close to the existing upper limit) and we
find that the value of the solar neutrino mixing angle is linked to the
magnitude of CP violation in neutrino oscillations. In the alternative case of
the neutrino sector correcting U_{e3} = 0 and theta_{23} = pi/4, we obtain a
generically smaller |U_{e3}| than in the first case. Now the magnitude of CP
violation in neutrino oscillations is connected to the value of the atmospheric
neutrino mixing angle theta_{23}. We find that both cases are in agreement with
present observations. We also introduce parametrization independent "sum-rules"
for the oscillation parameters.Comment: 19 pages, 3 figures. Comments and references adde
A complete 3D numerical study of the effects of pseudoscalar-photon mixing on quasar polarizations
We present the results of three-dimensional simulations of quasar
polarizations in the presence of pseudoscalar-photon mixing in the
intergalactic medium. The intergalactic magnetic field is assumed to be
uncorrelated in wave vector space but correlated in real space. Such a field
may be obtained if its origin is primordial. Furthermore we assume that the
quasars, located at cosmological distances, have negligible initial
polarization. In the presence of pseudoscalar-photon mixing we show, through a
direct comparison with observations, that this may explain the observed large
scale alignments in quasar polarizations within the framework of big bang
cosmology. We find that the simulation results give a reasonably good fit to
the observed data.Comment: 15 pages, 8 figures, significant changes, to appear in EPJ
Effects of Axion-Photon Mixing on Gamma-Ray Spectra from Magnetized Astrophysical Sources
9 revtex pages, 3 eps figures includedAstrophysical gamma-ray sources come in a variety of sizes and magnetizations. We deduce general conditions under which gamma-ray spectra from such sources would be significantly affected by axion-photon mixing. We show that, depending on strength and coherence of the magnetic field, axion couplings down to ~ (10^13 GeV)^-1 can give rise to significant axion-photon conversions in the environment of accreting massive black holes. Resonances can occur between the axion mass term and the plasma frequency term as well as between the plasma frequency term and the vacuum Cotton-Mouton shift. Both resonances and non-resonant transitions could induce detectable features or even strong suppressions in finite energy intervals of gamma-ray spectra from active galactic nuclei. Such effects can occur at keV to TeV energies for couplings that are currently allowed by all experimental constraints