arXiv subjects
Publications and source records attributed to T. J. Weiler.
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.
By combining experimental constraints from atmospheric and solar neutrino oscillations and the tritium beta decay endpoint, we infer upper limits of 4.4 eV on the $ν_μ$ and $ν_τ$ masses, if the universe consists of three neutrinos. For hierarchical mass spectra $m_3 \gg m_1, m_2$ or $m_3 \simeq m_2 \gg m_1$ we infer that $m_{ν_α} \lsim 0.08$ eV for $α= e, μ, τ$. In a four neutrino universe, and assuming neutrino oscillations also account for the LSND experimental results, $m_{ν_α} \lsim 5.4$ eV. We also obtain lower limits on the masses.
We determine the neutrino mixing and mass parameters that are allowed by the Super-Kamiokande atmospheric neutrino data in a three-neutrino model with one mass-squared difference contributing to the oscillations. We find that although $ν_μ\toν_τ$ oscillations are favored, $ν_μ\to ν_e$ oscillations with amplitude as large as 0.18 are allowed even after accounting for the limit from the CHOOZ reactor experiment. The range of allowed parameters permit observable $ν_μ\leftrightarrowν_e$ and $ν_e\toν_τ$ oscillations in future long-baseline experiments.
We show that if the solar and atmospheric data are both described by maximal vacuum oscillations at the relevant mass scales then there exists a unique mixing matrix for three neutrino flavors. The solution necessarily conserves CP and automatically implies that there is no disappearance of atmospheric $ν_e$, consistent with indications from the Super-Kamiokande experiment. We also investigate the consequences for three-neutrino mixing if the solar and atmospheric oscillations exhibit mixing that is large but not maximal. For non-maximal mixing $ν_e\leftrightarrowν_τ$ and $ν_e\leftrightarrowν_μ$ oscillations are predicted that may be observable in future long-baseline experiments.
We make a model-independent analysis of all available data that indicate neutrino oscillations. Using probability diagrams, we confirm that a mass spectrum with two nearly degenerate pairs of neutrinos separated by a mass gap of $\simeq1$ eV is preferred over a spectrum with one mass eigenstate separated from the others. We derive some new relations among the four-neutrino mixing matrix elements. We design four-neutrino mass matrices with three active neutrinos and one sterile neutrino that naturally incorporate maximal oscillations of atmospheric $ν_μ$ and explain the solar neutrino and LSND results. The models allow either a large or small angle MSW or vacuum oscillation description of the solar neutrino deficit. The models predict (i) oscillations of either $ν_e \to ν_τ$ or $ν_e \toν_s$ in long-baseline experiments at $L/E \gg 1$ km/GeV, with amplitude determined by the LSND oscillation amplitude and argument given by the atmospheric $δm^2$, and (ii) the equality of the $ν_e$ disappearance probability, the $ν_μ$ disappearance probability, and the LSND $ν_μ\toν_e$ appearance probability in short-baseline experiments.
We present a four-neutrino model with three active neutrinos and one sterile neutrino which naturally has maximal $ν_μ\toν_τ$ oscillations of atmospheric neutrinos and can explain the solar neutrino and LSND results. The model predicts $ν_e \to ν_τ$ and $ν_e \to ν_μ$ oscillations in long-baseline experiments with $L/E \gg 1$ km/GeV with amplitudes that are determined by the LSND oscillation amplitude and argument controlled by the atmospheric $δm^2$.
Gamma ray burst (GRB) objects are now widely thought to be at cosmological distances, and thus represent enormous energy emission. Gamma ray spectra extending to $GeV$ energies suggest the possiblity of accompanying neutrino emission, and there are several models proposed suggesting the potential detectability of such coincident neutrino bursts. With this in view, we examine possible measurements that might be conducted to give experimental data useful for astronomy, for cosmology and also neutrino properties. Of interest to astronomy and cosmology, we show how measurement of neutrino flavor ratios yields information on the nature and relative distance of the source. We point out that cosmological time dilation might be measured for these sources using neutrinos, as has been done for photons, and that neutrino oscillation lengths in the range of $1$ to $10^5~Mpc$ can be probed with GRB neutrinos. We thus note that these sources may make possible the first non-electromagnetic measurements of the scale size of the universe. We discuss tests of the weak equivalence principle, tests for flavor dependent gravitational couplings, and tests for long time scale variation of physical constants. We also show that a number of new bounds on neutrino properties (charge, mass, speed, lifetime) could be facilitated to levels well beyond those already inferred from the neutrino observation of SN1987A. We also examine the implications of these physics opportunities for designers of neutrino telescopes. We conclude that detection may be possible in planned instruments if the spectra are power law extending to the $TeV$ energy region, and if the neutrino fluxes are equal to or greater than the gamma ray fluxes. We emphasize the importance of low energy detection in future experiments
We present analytic solutions to the spatially homogeneous axion field equation, using a model potential which strongly resembles the standard anharmonic $(1-\cos Nθ)$ potential, but contains only a piece-wise second order term. Our exactly soluble model for $θ(t)$ spans the entire range $[-π/N,π/N]$. In particular, we are able to confirm (i) Turner's numeric correction factors \cite{Turner} to the adiabatic and harmonic analytic treatments of homogeneous axion oscillations, and (ii) Lyth's estimate \cite{Lyth} valid near the metastable misalignment angle $π/N$ at the peak of the potential. We compute the enhancement of axion density fluctuations that occurs when the axion mass becomes significant at $T\sim 1$ GeV. We find that the anharmonicity amplifies density \mbox{f}luctuations, but only significantly for relatively large initial misalignment angles. The enhancement factor is $\sim$ (2,3,4,13) for $θ_{\rm in}\sim (0.85,0.90,0.95,0.99)\timesπ$.