48 research outputs found
Constraints on Unparticles from Low Energy Neutrino-Electron Scattering
We place limits on scalar and vector unparticle couplings to electrons and
neutrinos using data from reactor neutrino experiments originally designed to
search for neutrino magnetic moment. Upper bounds on Standard Model
lepton-scalar unparticle and lepton-vector unparticle couplings ,
and are given for various values of the unparticle mass dimension
d, and the unparticle energy scale . Especially for smaller
values of the mass dimension d (1 <d <1.3) these bounds are very significant
and comparable to those obtained from production rates at high energy
colliders. These bounds are also similar to those obtained by the analysis of
the absence of the decay of the low-energy solar and reactor neutrinos.Comment: 6 pages of LATEX, 3 figure
Prospects for measuring coherent neutrino-nucleus elastic scattering at a stopped-pion neutrino source
Rates of coherent neutrino-nucleus elastic scattering at a high-intensity
stopped-pion neutrino source in various detector materials (relevant for novel
low-threshold detectors) are calculated. Sensitivity of a coherent
neutrino-nucleus elastic scattering experiment to new physics is also explored.Comment: 9 pages, 14 figures; minor modifications for publicatio
Fermionic Effective Operators and Higgs Production at a Linear Collider
We study the possible contributions of dimension six operators containing
fermion fields to Higgs production at a 500 GeV or 1 TeV linear
collider. We show that -- depending on the production mechanism -- the effects
of such operators can be kinematically enhanced relative to Standard Model (SM)
contributions. We determine constraints on the operator coefficients implied by
existing precision electroweak measurements and the scale of neutrino mass. We
find that even in the presence of such constraints, substantial deviations from
SM Higgs production cross-sections are possible. We compare the effects of
fermionic operators with those associated with purely bosonic operators that
have been previously discussed in the literature.Comment: 25 pages, 9 figures, fixed typo in author name
Neutrino Mass Implications for Muon Decay Parameters
We use the scale of neutrino mass to derive model-independent naturalness
constraints on possible contributions to muon decay Michel parameters from new
physics above the electroweak symmetry-breaking scale. Focusing on Dirac
neutrinos, we obtain a complete basis of effective dimension four and dimension
six operators that are invariant under the gauge symmetry of the Standard Model
and that contribute to both muon decay and neutrino mass. We show that -- in
the absence of fine tuning -- the most stringent bounds on chirality-changing
operators relevant to muon decay arise from one-loop contributions to neutrino
mass. The bounds we obtain on their contributions to the Michel parameters are
four or more orders of magnitude stronger than bounds previously obtained in
the literature. We also show that there exist chirality-changing operators that
contribute to muon decay but whose flavor structure allows them to evade
neutrino mass naturalness bounds. We discuss the implications of our analysis
for the interpretation of muon decay experiments.Comment: 19 pages, 4 figure
Geological controls on radon potential in Northern Ireland
Moderate and high radon potential in Northern Ireland is associated mainly with (i) the Neoproterozoic psammites, semipelites, meta-limestones, volcanics and mafic intrusives of Counties Londonderry and Tyrone; (ii) Silurian Hawick Group greywackes and, to a much more limited extent Gala Group greywackes, in the southern sector of Counties Armagh and Down; (iii) Ordovician and Silurian acid intrusives and volcanics in eastern Counties Londonderry and Tyrone; (iv) Middle-Late Devonian conglomerates in County Tyrone; (v) Lower Carboniferous (Dinantian) limestone in the western sector of Northern Ireland, especially in County Fermanagh; (vi) Palaeogene and Late Caledonian acid intrusive rocks of the Mourne Mountains Complex, Slieve Gullion Complex and Newry Granodiorite Complex in the SE sector in County Down and County Armagh.
Moderate to high radon potential is sometimes associated with glacio-fluvial sand and gravel deposits where these overlie a range of bedrocks, some of which have relatively low radon potential. In this latter case the enhanced radon potential is probably caused by the high permeability of superficial deposits. Radon potential tends to be lower when bedrocks characterised by moderate or high radon potential are overlain by relatively impermeable silt-clay alluvium, glaciolacustrine, and lacustrine deposits; peat; and glacial till and moraine. Redistribution of rock debris derived from uranium-rich bedrocks, such as the Mourne Mountains granites, through glacial, alluvial and other processes can also result in higher radon potential being associated with superficial deposits relative to underlying bedrock
Electromagnetic Leptogenesis
We present a new leptogenesis scenario, where the lepton asymmetry is
generated by CP violating decays of heavy electroweak singlet neutrinos via
electromagnetic dipole moment couplings to the ordinary light neutrinos. Akin
to the usual scenario where the decays are mediated through Yukawa
interactions, we have shown, by explicit calculations, that the desired
asymmetry can be produced through the interference of the corresponding
tree-level and one-loop decay amplitudes involving the effective dipole moment
operators. We also find that the relationship of the leptogenesis scale to the
light neutrino masses is similar to that for the standard Yukawa-mediated
mechanism.Comment: 6 pages, 6 figures; v2: some references added, minor change to
discussion, accepted by PR
New gas mixtures suitable for rare event detection using a Micromegas-TPC detector
The aim of the presented work was to develop further techniques based on a
Micromegas-TPC, in order to reach a high gas gain with good energy resolution,
and to search for gas mixtures suitable for rare event detection. This paper
focuses on xenon, which is convenient for the search of neutrinoless double
beta decay in 136 Xe. Conversely, a small admixture of xenon to CF 4 can reduce
attachment in the latter. This gas mixture would be suitable for dark matter
searches and the study of solar and reactor neutrinos. Various configurations
of the Micromegas plane were investigated and are described.Comment: 14 pages, 8 figures, article, revised version with improved figures,
text modifications, accepted for publication by JINS
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
Unparticle physics and neutrino phenomenology
We have constrained unparticle interactions with neutrinos and electrons
using available data on neutrino-electron elastic scattering and the four CERN
LEP experiments data on mono photon production. We have found that, for
neutrino-electron elastic scattering, the MUNU experiment gives better
constraints than previous reported limits in the region d>1.5. The results are
compared with the current astrophysical limits, pointing out the cases where
these limits may or may not apply. We also discuss the sensitivity of future
experiments to unparticle physics. In particular, we show that the measurement
of coherent reactor neutrino scattering off nuclei could provide a good
sensitivity to the couplings of unparticle interaction with neutrinos and
quarks. We also discuss the case of future neutrino-electron experiments as
well as the International Linear Collider.Comment: 20 pages, 5 figures. Minor changes, final versio
Low energy tracking and particles identification in the MUNU Time Projection Chamber at 1 bar. Possible application in low energy solar neutrino spectroscopy
In this paper we present the results from the measurements made with the MUNU
TPC at 1bar pressure of CF4 in the energy region below 1 MeV. Electron events
down to 80 keV are successfully measured. The electron energy and direction are
reconstructed for every contained single electron above 200 keV. As test the
137Cs photopeak is reconstructed by measuring both the energy and direction of
the Compton electrons in the TPC.Comment: 19 pages, 9 figures (6 figures in color); Figure 10 has been deleted
from [v1]. Additional paragraph has been included; Manuscript is submitted to
Nuclear Inst. and Methods in Physics Research,