127 research outputs found
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
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
Proton Hexality from an Anomalous Flavor U(1) and Neutrino Masses - Linking to the String Scale
We devise minimalistic gauged U(1)_X Froggatt-Nielsen models which at
low-energy give rise to the recently suggested discrete gauge Z_6 symmetry,
proton hexality, thus stabilizing the proton. Assuming three generations of
right-handed neutrinos, with the proper choice of X-charges, we obtain viable
neutrino masses. Furthermore, we find scenarios such that no X-charged hidden
sector superfields are needed, which from a bottom-up perspective allows the
calculation of g_string, g_X and G_SM's Kac-Moody levels. The only mass scale
apart from M_grav is m_soft.Comment: 32 pages, 8 tables, references updated, matches published versio
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