150 research outputs found
Analytic Calculation of Neutrino Mass Eigenvalues
Implicaion of the neutrino oscillation search for the neutrino mass square
difference and mixing are discussed. We have considered the effective majorana
mass m_{ee}, related for \beta\beta_{0\nu}decay. We find limits for neutrino
mass eigen value m_{i} in the different neutrino mass spectrum,which explain
the different neutrino data.Comment: 10 page
Search for Radiative Decays of Cosmic Background Neutrino using Cosmic Infrared Background Energy Spectrum
We propose to search for the neutrino radiative decay by fitting a photon
energy spectrum of the cosmic infrared background to a sum of the photon energy
spectrum from the neutrino radiative decay and a continuum. By comparing the
present cosmic infrared background energy spectrum observed by AKARI and
Spitzer to the photon energy spectrum expected from neutrino radiative decay
with a maximum likelihood method, we obatined a lifetime lower limit of to years at 95% confidence level for the
third generation neutrino in the mass range between 50 \mmev
and 150 \mmev under the present constraints by the neutrino oscillation
measurements. In the left-right symmetric model, the minimum lifetime of
is predicted to be years for of 50 \mmev. We
studied the feasibility of the observation of the neutrino radiative decay with
a lifetime of years, by measuring a continuous energy
spectrum of the cosmic infrared background
SO(3) Gauge Symmetry and Nearly Tri-bimaximal Neutrino Mixing
In this note I mainly focus on the neutrino physics part in my talk and
report the most recent progress made in \cite{YLW0}. It is seen that the
Majorana features of neutrinos and SO(3) gauge flavor symmetry can
simultaneously explain the smallness of neutrino masses and nearly
tri-bimaximal neutrino mixing when combining together with the mechanism of
approximate global U(1) family symmetry. The mixing angle and
CP-violating phase are in general nonzero and testable experimentally at the
allowed sensitivity. The model also predicts the existence of vector-like
Majorana neutrinos and charged leptons as well as new Higgs bosons, some of
them can be light and explored at the LHC and ILC.Comment: 8 pages, invited talk, contribute to the Proceedings of the 4th
International Conference on Flavor Physics (ICFP2007
Self-shielding effect of a single phase liquid xenon detector for direct dark matter search
Liquid xenon is a suitable material for a dark matter search. For future
large scale experiments, single phase detectors are attractive due to their
simple configuration and scalability. However, in order to reduce backgrounds,
they need to fully rely on liquid xenon's self-shielding property. A prototype
detector was developed at Kamioka Observatory to establish vertex and energy
reconstruction methods and to demonstrate the self-shielding power against
gamma rays from outside of the detector. Sufficient self-shielding power for
future experiments was obtained.Comment: 8 pages, 8 figure
Testing the LMA solution with solar neutrinos independently of solar models
We perform a comparative study of two methods of determining the survival
probabilities of low, intermediate, and high energy solar neutrinos that
emphasizes the general agreement between the Large Mixing Angle (LMA) solution
and extant solar neutrino data. The first analysis is oscillation
parameter-independent and the second analysis involves an approximate
calculation of the survival probabilities in the three energy ranges that
depends only on oscillation parameters. We show that future experiments like
BOREXino, CLEAN, Heron, LENS and MOON, that measure and Be neutrinos,
will facilitate a stringent test of the LMA solution independently of the
Standard Solar Model (SSM), without recourse to earth-matter effects.
Throughout, we describe the role of SSM assumptions on our results. If the LMA
solution passes the test without needing to be modified, it may be possible to
establish that is nonzero at more than assuming the SSM
prediction for the flux is correct.Comment: Final SNO salt-phase data included in analysis. Version to appear in
PL
Preliminary findings from stimulated spontaneous reporting of adverse drug reactions during COVID-19 pandemic: an experience from Ghana
Background: The novel coronavirus disease 2019 (COVID-19) is an ongoing pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). There is limited information on the safety of drugs used for the treatment of COVID-19.Objective: Objective of this study is to describe the pattern of stimulated spontaneous adverse drug reaction (ADR) reports received from healthcare professionals for SARS-CoV-2 positive patients in Ghana and lessons learnt particularly for low- and middle-income countries.Methods: This is a study of individual case safety reports (ICSRs) received from healthcare professionals between 1st April 2020 to 31st July 2020 in SARS-CoV-2 positive patients in Ghana. The ICSRs were retrieved from the SafetyWatch System and descriptive statistics used to describe the ADRs by System Organ Classification and Preferred Term.Results: Information was received from 40 COVID-19 Treatment Centres across the country with 9 centres submitting a total of 53 ICSRs containing 101 ADRs; approximately two ADRs per ICSR. Females accounted for 29(54.7%) of the ICSRs and males 24(45.3%). Newly reported ADRs of interest were one report each of tremor for doxycycline; scrotal pain, dyspnoea, gait disturbances and dysgeusia for chloroquine; and dry throat, hyperhidrosis, restlessness and micturition frequency increased for hydroxychloroquine. A strong spontaneous system with the availability of focal persons at the Treatment Centres played a key role in reporting ADRs during the pandemic.Conclusion: This is the first experience with spontaneous reporting during COVID-19 pandemic in Ghana. The profile of most of the ADRs reported appears consistent with what is expected from the summary of product characteristics. A study with a larger sample size with well-defined denominator in future studies is paramount in determining the relative risk of these medications in SARS-CoV-2 positive patients
Large-Theta(13) Perturbation Theory of Neutrino Oscillation for Long-Baseline Experiments
The Cervera et al. formula, the best known approximate formula of neutrino
oscillation probability for long-baseline experiments, can be regarded as a
second-order perturbative formula with small expansion parameter epsilon \equiv
Delta m^2_{21} / Delta m^2_{31} \simeq 0.03 under the assumption s_{13} \simeq
epsilon. If theta_{13} is large, as suggested by a candidate nu_{e} event at
T2K as well as the recent global analyses, higher order corrections of s_{13}
to the formula would be needed for better accuracy. We compute the corrections
systematically by formulating a perturbative framework by taking theta_{13} as
s_{13} \sim \sqrt{epsilon} \simeq 0.18, which guarantees its validity in a wide
range of theta_{13} below the Chooz limit. We show on general ground that the
correction terms must be of order epsilon^2. Yet, they nicely fill the mismatch
between the approximate and the exact formulas at low energies and relatively
long baselines. General theorems are derived which serve for better
understanding of delta-dependence of the oscillation probability. Some
interesting implications of the large theta_{13} hypothesis are discussed.Comment: Fig.2 added, 23 pages. Matches to the published versio
Baryon Triality and Neutrino Masses from an Anomalous Flavor U(1)
We construct a concise U(1)_X Froggatt-Nielsen model in which baryon
triality, a discrete gauge Z_3 symmetry, arises from U(1)_X breaking. The
proton is thus stable, however, R-parity is violated. With the proper choice of
U(1)_X charges we can obtain neutrino masses and mixings consistent with an
explanation of the atmospheric and solar neutrino anomalies in terms of
neutrino oscillations, with no right-handed neutrinos required. The only mass
scale apart from M_grav is m_3/2 ~ m_soft.Comment: matches published version, typos corrected, references added, 54
pages, 3 figures, 5 table
Evaluation of radioactive background rejection in 76Ge neutrino-less double-beta decay experiments using a highly segmented HPGe detector
Evidence for an oscillatory signature in atmospheric neutrino oscillation
Muon neutrino disappearance probability as a function of neutrino flight
length L over neutrino energy E was studied. A dip in the L/E distribution was
observed in the data, as predicted from the sinusoidal flavor transition
probability of neutrino oscillation. The observed L/E distribution constrained
nu_mu nu_tau neutrino oscillation parameters; 1.9x10^-3 < Delta m^2 <
3.0x10^-3 eV^2 and \sin^2(2theta) > 0.90 at 90% confidence level.Comment: 5 pages, 5 figures, submitted to PR
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