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 $3.1 \times 10^{12}$ to $3.8 \times 10^{12}$ years at 95% confidence level for the third generation neutrino $\nu_3$ in the $\nu_3$ 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 $\nu_3$ is predicted to be $1.5 \times 10^{17}$ years for $m_3$ of 50 \mmev. We studied the feasibility of the observation of the neutrino radiative decay with a lifetime of $1.5 \times 10^{17}$ 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 $\theta_{13}$ 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 $pp$ and $^7$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 $\theta_x$ is nonzero at more than $2\sigma$ assuming the SSM prediction for the $pp$ 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

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