76 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
Search for neutrinoless double beta decay with NEMO 3 experiment
NEMO 3 experiment is designed to search for neutrinoless double beta decay.
It is located in the Modane Underground Laboratory (LSM) and has been taking
data since February 2003. The half- lives of two neutrino beta decay have been
measured for seven isotopes. No evidence of neutrinoless double beta decay has
been found. The limits on both the half-lives of the neutrinoless double beta
decay and the corresponding Majorana effective masses are derivedComment: 3 pages, 2 figures, 2 tables, PANIC08 Conference proceeding
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
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
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
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
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