Constraints on decay plus oscillation solutions of the solar neutrino problem

We examine the constraints on non-radiative decay of neutrinos from the observations of solar neutrino experiments. The standard oscillation hypothesis among three neutrinos solves the solar and atmospheric neutrino problems. Decay of a massive neutrino mixed with the electron neutrino results in the depletion of the solar neutrino flux. We introduce neutrino decay in the oscillation hypothesis and demand that decay does not spoil the successful explanation of solar and atmospheric observations. We obtain a lower bound on the ratio of the lifetime over the mass of $\nu_2$, (\tau_2/m_2) > 22.7 (\srm/\MeV) for the MSW solution of the solar neutrino problem and (\tau_2/m_2) > 27.8 (\srm/\MeV) for the VO solution (at 99% C.L.).Comment: 8 pages latex file with 4 figure

MSW mediated neutrino decay and the solar neutrino problem

We investigate the solar neutrino problem assuming simultaneous presence of MSW transitions in the sun and neutrino decay on the way from sun to earth. We do a global $\chi^2$-analysis of the data on total rates in Cl, Ga and Superkamiokande (SK) experiments and the SK day-night spectrum data and determine the changes in the allowed region in the \dm - \tan^2\theta plane in presence of decay. We also discuss the implications for unstable neutrinos in the SNO experiment.Comment: Final version to appear in Phys. Rev.

Neutrino-Mixing-Generated Lepton Asymmetry and the Primordial 4^4He Abundance

It has been proposed that an asymmetry in the electron neutrino sector may be generated by resonant active-sterile neutrino transformations during Big Bang Nucleosynthesis (BBN). We calculate the change in the primordial $^4$He yield $Y$ resulting from this asymmetry, taking into account both the time evolution of the $\nu_e$ and $\bar\nu_e$ distribution function and the spectral distortions in these. We calculate this change in two schemes: (1) a lepton asymmetry directly generated by $\nu_e$ mixing with a lighter right-handed sterile neutrino $\nu_s$; and (2) a lepton asymmetry generated by a $\nu_\tau\leftrightarrow\nu_s$ or $\nu_\mu\leftrightarrow\nu_s$ transformation which is subsequently partially converted to an asymmetry in the $\nu_e\bar\nu_e$ sector by a matter-enhanced active-active neutrino transformation. In the first scheme, we find that the percentage change in $Y$ is between -1% and 9% (with the sign depending on the sign of the asymmetry), bounded by the Majorana mass limit m_{\nu_e}\la 1 eV. In the second scheme, the maximal percentage reduction in $Y$ is 2%, if the lepton number asymmetry in neutrinos is positive; Otherwise, the percentage increase in $Y$ is \la 5% for m^2_{\nu_\mu,\nu_\tau}-m^2_{\nu_s}\la 10^4 eV. We conclude that the change in the primordial $^4$He yield induced by a neutrino-mixing-generated lepton number asymmetry can be substantial in the upward direction, but limited in the downward direction.Comment: 15 pages, 7 figures, submitted to PR

Neutrino Decay as an Explanation of Atmospheric Neutrino Observations

We show that the observed zenith angle dependence of the atmospheric neutrinos can be accounted for by neutrino decay. Furthermore, it is possible to account for all neutrino anomalies with just three flavors.Comment: 4 pages, 1 figur

Voltage imaging reveals the dynamic electrical signatures of human breast cancer cells

Cancer cells feature a resting membrane potential (Vm) that is depolarized compared to normal cells, and express active ionic conductances, which factor directly in their pathophysiological behavior. Despite similarities to ‘excitable’ tissues, relatively little is known about cancer cell Vm dynamics. Here high-throughput, cellular-resolution Vm imaging reveals that Vm fluctuates dynamically in several breast cancer cell lines compared to non-cancerous MCF-10A cells. We characterize Vm fluctuations of hundreds of human triple-negative breast cancer MDA-MB-231 cells. By quantifying their Dynamic Electrical Signatures (DESs) through an unsupervised machine-learning protocol, we identify four classes ranging from "noisy” to “blinking/waving“. The Vm of MDA-MB-231 cells exhibits spontaneous, transient hyperpolarizations inhibited by the voltage-gated sodium channel blocker tetrodotoxin, and by calcium-activated potassium channel inhibitors apamin and iberiotoxin. The Vm of MCF-10A cells is comparatively static, but fluctuations increase following treatment with transforming growth factor-β1, a canonical inducer of the epithelial-to-mesenchymal transition. These data suggest that the ability to generate Vm fluctuations may be a property of hybrid epithelial-mesenchymal cells or those originated from luminal progenitors

Neutrino Lasing in the Sun

Applying the phenomenon of neutrino lasing in the solar interior, we show how the rate for the generic neutrino decay process `\nu -> fermion + boson', can in principal be enhanced by many orders of magnitude over its normal decay rate. Such a large enhancement could be of import to neutrino-decay models invoked in response to the apparent deficit of electron neutrinos observed from the sun. The significance of this result to such models depends on the specific form of the neutrino decay, and the particle model within which it is embedded.Comment: 12 pages, using ordinary TeX. No figure

Neutrino Anomalies without Oscillations

I review explanations for the three neutrino anomalies (solar, atmospheric and LSND) which go beyond the ``conventional'' neutrino oscillations induced by mass-mixing. Several of these require non-zero neutrino masses as well.Comment: 14pages, LATEX format, 3 figure

Role of lepton flavor violating (LFV) muon decay in Seesaw model and LSND

The aim of the work is to study LFV in a newly proposed Seesaw model of neutrino mass and to see whether it could explain LSND excess. The motivation of this Seesaw model was that there was no new physics beyond the TeV scale. By studying \mu \to 3e in this model, it is shown that the upper bound on the branching ratio requires Higgs mass m_{h} of a new scalar doublet with lepton number L=-1 needed in the model has to be about 9 TeV. The predicted branching ratio for \mu \to e\nu_{l}\bar{\nu}_{l} is too small to explain the LSND. PACS: 11.30.Hv, 14.60.PqComment: 05 pages, three figures, the version to appear in PR

Energy Independent Solution to the Solar Neutrino Anomaly including the SNO data

The global data on solar neutrino rates and spectrum, including the SNO charged current rate, can be explained by LMA, LOW or the energy independent solution -- corresponding to near-maximal mixing. All the three favour a mild upward renormalisation of the Cl rate. A mild downward shift of the $B$ neutrino flux is favoured by the energy independent and to a lesser extent the LOW solution, but not by LMA. Comparison with the ratio of SK elastic and SNO charged current scattering rates favours the LMA over the other two solutions, but by no more than $1.5\sigma$.Comment: 18 pages, latex, 3 figure

Knots in the outer shells of the planetary nebulae IC 2553 and NGC 5882

We present images and high-resolution spectra of the planetary nebulae IC 2553 and NGC 5882. Spatio-kinematic modeling of the nebulae shows that they are composed of a markedly elongated inner shell, and of a less aspherical outer shell expanding at a considerably higher velocity than the inner one. Embedded in the outer shells of both nebulae are found several low-ionization knots. In IC 2553, the knots show a point-symmetric distribution with respect to the central star: one possible explanation for their formation is that they are the survivors of pre-existing point-symmetric condensations in the AGB wind, a fact which would imply a quite peculiar mass-loss geometry from the giant progenitor. In the case of NGC 5882, the lack of symmetry in the distribution of the observed low-ionization structures makes it possible that they are the result of in situ instabilities.Comment: 20 pages including 1 table and 6 figures. ApJ accepted. Also available at http://andromeda.roque.ing.iac.es/~sanchez/ingpub/index2000.htm