The minimum width condition for neutrino conversion in matter

We find that for small vacuum mixing angle $\theta$ and low energies ($s\ll M^2_Z$) the width of matter, $d_{1/2}$, needed to have conversion probability $P\geq 1/2$ should be larger than $d_{min}= \pi/(2\sqrt{2} G_{F} \tan 2 \theta)$: $d_{1/2}\geq d_{min}$. Here $G_F$ is the Fermi constant, $s$ is the total energy squared in the center of mass and $M_Z$ is the mass of the $Z$ boson. The absolute minimum $d_{1/2}=d_{min}$ is realized for oscillations in a uniform medium with resonance density. For all the other density distributions (monotonically varying density, castle wall profile, etc.) the required width $d_{1/2}$ is larger than $d_{min}$. The width $d_{min}$ depends on $s$, and for $Z$-resonance channels at $s\sim M^2_Z$ we get that $d_{min}(s)$ is 20 times smaller than the low energy value. We apply the minimum width condition, $d\geq d_{min}$, to high energy neutrinos in matter as well as in neutrino background. Using this condition, we conclude that the matter effect is negligible for neutrinos propagating in AGN and GRBs environments. Significant conversion can be expected for neutrinos crossing dark matter halos of clusters of galaxies and for neutrinos produced by cosmologically distant sources and propagating in the universe.Comment: 35 pages, latex, 5 figures, structure of the paper is slightly changed, typos correcte

Possible electric charge nonconservation and dequantization in SU(2)×U(1)SU(2) \times U(1) models with hard symmetry breaking

We study a novel type of extensions of the Standard Model which include a hard mass term for the U(1) gauge field and, optionally, the additional scalar multiplets spontaneously violating the electric charge conservation. Contrary to the case of abelian massive electrodynamics, in these theories the massiveness of photon necessarily implies non-conservation (and also dequantization) of the electric charge (even in the absence of spontaneous breakdown of the electromagnetic symmetry). On the other hand, unexpectedly, there exist models with charge non-conservation where it is possible to keep the photon mass zero (at least, at the tree level).Comment: 10 pages, revtex, no figures, to appear in Physics Letters

Magnetic Monopole and the Finite Photon Mass: Are They Compatible?

We analyze the role played by the gauge invariance for the existence of Dirac monopole. To this end, we consider the electrodynamics with massive photon and ask if the magnetic charge can be introduced there. We show that the derivation of the Dirac quantization condition based on the angular momentum algebra cannot be generalized to the case of massive electrodynamics. Possible implications of this result are briefly discussed.Comment: 12 pages, revtex, no figure

The Charged Neutrino: A New Approach to the Solar Neutrino Problem

We have considered the effect of the reduction of the solar neutrino flux on earth due to the deflection of the charged neutrino by the magnetic field of the solar convective zone. The antisymmetry of this magnetic field about the plane of the solar equator induces the anisotropy of the solar neutrino flux thus creating the deficit of the neutrino flux on the earth. The deficit has been estimated in terms of solar and neutrino parameters and the condition of a 50 \% deficit has been obtained: Q_{\nu} gradH \agt 10^{-18} eG/cm where $Q_{\nu}$ is the neutrino electric charge, $gradH$ is the gradient of the solar toroidal magnetic field, e is the electron charge. Some attractive experimental consequences of this scenario are qualitatively discussed.Comment: 15 pages, UM-P/94-26, in REVTE

Non-Zero Electric Charge of the Neutrino and the Solar Neutrino Problem

It has recently been shown that the neutrino can have non-zero electric charge in a number of gauge theories, including the Minimal Standard Model. Assuming non-zero neutrino charge, we develop a new approach to the solar neutrino problem. The key idea is that the charged neutrinos will be deflected by the Lorentz force while they are crossing the solar magnetic fields. Such a deflection will result in the anisotropy of the solar neutrino flux. Because of this anisotropy, the solar neutrino flux registered on earth can be reduced as compared to the Standard Solar Model prediction. The mechanism is purely classical and does not require neutrino oscillations, spin-flip or neutrino decay. We discuss qualitatively the consequences of our scenario for present and future solar neutrino experiments as well as differences between our mechanism and other proposed solutions.Comment: 29 pages, UM-P/94-73, RCHEP-94/21, in REVTE

Black holes with magnetic charge and quantized mass

We examine the issue of magnetic charge quantization in the presence of black holes. It is pointed out that quantization of magnetic charge can lead to the mass quantization for magnetically charged black holes. We also discuss some implications for the experimental searches of magnetically charged black holes.Comment: RevTeX, 11 pages, Invited paper for the first editorial volume of the book series "Contemporary Fundamental Physics" by the Nova Science Publisher

A lattice study of the pentaquark states

We present a study of the pentaquark system in quenched lattice QCD using diquark-diquark and kaon-nucleon local and smeared interpolating fields. We examine the volume dependence of the spectral weights of local correlators on lattices of size $16^3\times 32$, $24^3\times32$ and $32^3\times 64$ at $\beta=6.0$. We find that a reliable evaluation of the volume dependence of the spectral weights requires accurate determination of the correlators at large time separations. Our main result from the spectral weight analysis in the pentaquark system is that within our variational basis and statistics we can not exclude a pentaquark resonance. However our data also do not allow a clear identification of a pentaquark state since only the spectral weights of the lowest state can be determined to sufficient accuracy to test for volume dependence. In the negative parity channel the mass extracted for this state is very close to the KN threshold whereas in the positive parity channel is about 60% above.Comment: Manuscript expanded, discussion of two-pion system included, a comment regarding Ref.13 was corrected, version to appear in Phys. Rev. D, 19 figure