612 research outputs found
Does the neutrino magnetic moment have an impact on solar neutrino physics?
Solar neutrino observations coupled with the recent KamLAND data suggest that
spin-flavor precession scenario does not play a major role in neutrino
propagation in the solar matter. We provide approximate analytical formulas and
numerical results to estimate the contribution of the spin-flavor precession,
if any, to the electron neutrino survival probability when the magnetic moment
and magnetic field combination is small.Comment: 7 pages, 1 figure
Prospects for Detecting a Neutrino Magnetic Moment with a Tritium Source and Beta-beams
We compare the prospects for detecting a neutrino magnetic moment by the
measurement of neutrinos from a tritium source, reactors and low-energy
beta-beams. In all cases the neutrinos or antineutrinos are detected by
scattering of electrons. We find that a large (20 MCurie) tritium source could
improve the limit on the neutrino magnetic moment significantly, down to the
level of a few while low-energy beta-beams with sufficiently
rapid production of ions could improve the limits to the level of a few . The latter would require ion production at the rate of at least
s.Comment: 6 pages, 3 figure
Constraining Nonstandard Neutrino-Electron Interactions
We present a detailed analysis on nonstandard neutrino interactions (NSI)
with electrons including all muon and electron (anti)-neutrino data from
existing accelerators and reactors, in conjunction with the ``neutrino
counting'' data (e- e+ -> nu nu gamma) from the four LEP collaborations. First
we perform a one-parameter-at-a-time analysis, showing how most constraints
improve with respect to previous results reported in the literature. We also
present more robust results where the NSI parameters are allowed to vary freely
in the analysis. We show the importance of combining LEP data with the other
experiments in removing degeneracies in the global analysis constraining
flavor-conserving NSI parameters which, at 90 % and 95 % C.L., must lie within
unique allowed regions. Despite such improved constraints, there is still
substantial room for improvement, posing a big challenge for upcoming
experiments.Comment: 19 pages, 4 figures. Final version to appear in Phys. Rev.
Neutrino magnetic moments, flavor mixing, and the SuperKamiokande solar data
We find that magnetic neutrino-electron scattering is unaffected by
oscillations for vacuum mixing of Dirac neutrinos with only diagonal moments
and for Majorana neutrinos with two flavors. For MSW mixing, these cases again
obtain, though the effective moments can depend on the neutrino energy. Thus,
e.g., the magnetic moments measured with from a reactor and
from the Sun could be different. With minimal assumptions, we find a
new limit on using the 825-days SuperKamiokande solar neutrino
data: at 90% CL, comparable to the
existing reactor limit.Comment: 4 pages including two inline figures. New version has 825 days SK
result, some minor revisions. Accepted for Physical Review Letter
Limits on the neutrino magnetic moment from the MUNU experiment
The MUNU experiment was carried out at the Bugey nuclear power reactor. The
aim was the study of electron antineutrino-electron elastic scattering at low
energy. The recoil electrons were recorded in a gas time projection chamber,
immersed in a tank filled with liquid scintillator serving as veto detector,
suppressing in particular Compton electrons. The measured electron recoil
spectrum is presented. Upper limits on the neutrino magnetic moment were
derived and are discussed.Comment: 9 pages, 7 figures Added reference: p.3, 1st col., TEXONO Added
sentence: p.4, 1st col., electron attachement Modified sentence: p.5, 1st
col., readout sequence Added sentence: p.5, 1st col., fast rise time cu
Neutrinos in a spherical box
In the present paper we study some neutrino properties as they may appear in
the low energy neutrinos emitted in triton decay with maximum neutrino energy
of 18.6 keV. The technical challenges to this end can be achieved by building a
very large TPC capable of detecting low energy recoils, down to a a few tenths
of a keV, within the required low background constraints. More specifically We
propose the development of a spherical gaseous TPC of about 10-m in radius and
a 200 Mcurie triton source in the center of curvature. One can list a number of
exciting studies, concerning fundamental physics issues, that could be made
using a large volume TPC and low energy antineutrinos: 1) The oscillation
length involving the small angle of the neutrino mixing matrix, directly
measured in this disappearance experiment, is fully contained inside the
detector. Measuring the counting rate of neutrino-electron elastic scattering
as a function of the distance of the source will give a precise and unambiguous
measurement of the oscillation parameters free of systematic errors. In fact
first estimates show that even with a year's data taking a sensitivity of a few
percent for the measurement of the above angle will be achieved. 2) The low
energy detection threshold offers a unique sensitivity for the neutrino
magnetic moment which is about two orders of magnitude beyond the current
experimental limit. 3) Scattering at such low neutrino energies has never been
studied and any departure from the expected behavior may be an indication of
new physics beyond the standard model. In this work we mainly focus on the
various theoretical issues involved including a precise determination of the
Weinberg angle at very low momentum transfer.Comment: 16 Pages, LaTex, 7 figures, talk given at NANP 2003, Dubna, Russia,
June 23, 200
Searches for axioelectric effect of solar axions with BGO-scintillator and BGO-bolometer detectors
A search for axioelectric absorption of 5.5 MeV solar axions produced in the
reaction has been
performed with a BGO detectors. A model-independent limit on the product of
axion-nucleon and axion-electron coupling constants has
been obtained: for 90\% C.L..Comment: 5 pages, 3 figures, Proceedings of the 10th Patras Workshop on
Axions, WIMPs and WISP 29 June - 4 July 2014, CERN, Geneva, Switzerlan
Effects of neutrino oscillations and neutrino magnetic moments on elastic neutrino-electron scattering
We consider elastic antineutrino-electron scattering taking into account
possible effects of neutrino masses and mixing and of neutrino magnetic moments
and electric dipole moments. Having in mind antineutrinos produced in a nuclear
reactor we compute, in particular, the weak-electromagnetic interference terms
which are linear in the magnetic (electric dipole) moments and also in the
neutrino masses. We show that these terms are, however, suppressed compared to
the pure weak and electromagnetic cross section. We also comment upon the
possibility of using the electromagnetic cross section to investigate neutrino
oscillations.Comment: 12 pages, REVTEX file, no figures, submitted to Phys.Rev.
Neutrino scattering on polarized electron target and neutrino magnetic moment
The completed and proposed experiments for the measurement of the neutrino
magnetic moment are discussed. To improve the sensitivity of the search for the
neutrino magnetic moment we suggest to use a polarized electron target in the
processes of neutrino (antineutrino) -- electron scattering. It is shown that
in this case the weak interaction term in the total cross section is few times
smaller comparing with unpolarized case, but the electromagnetic term does not
depend on electron polarization.Comment: 12 pages, 7 figures. Talk given at the XXVIII ITEP Winter School of
Physics, Snegiri, Russia, February 22 - March 1, 200
Heat flow of the Earth and resonant capture of solar 57-Fe axions
In a very conservative approach, supposing that total heat flow of the Earth
is exclusively due to resonant capture inside the Earth of axions, emitted by
57-Fe nuclei on Sun, we obtain limit on mass of hadronic axion: m_a<1.8 keV.
Taking into account release of heat from decays of 40-K, 232-Th, 238-U inside
the Earth, this estimation could be improved to the value: m_a<1.6 keV. Both
the values are less restrictive than limits set in devoted experiments to
search for 57-Fe axions (m_a<216-745 eV), but are much better than limits
obtained in experiments with 83-Kr (m_a<5.5 keV) and 7-Li (m_a<13.9-32 keV).Comment: 8 page
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