Symmetry Problems in Low Energy Physics

Some recent experimental and theoretical work on 1) charge symmetry-breaking, 2) parity non-conservation, and 3) searches for breaking of time reversal invariance are reviewed. The examples illustrate the uses of symmetry to learn about underlying dynamics and/or structure.Comment: 15 pages, tex, figures available from [email protected] Talk presented at WEIN'9

Neutrino Properties, Cosmology

Review of neutrino properties; double beta decay; very high energy neutrinos; leptogenesisComment: 10 pages, 3 figures; conference tal

Determination of flavor asymmetry for Σ±\Sigma^{\pm} by the Drell-Yan process

Flavor asymmetries for the valence and sea quarks of the $\Sigma^{\pm}$ can be obtained from Drell-Yan experiments using charged hyperon beams on proton and deuteron targets. A large, measurable difference in sea quark asymmetries is predicted between SU(3) and pseudoscalar meson models. The latter predict that in $\Sigma^{+}$, $\bar{u}/\bar{d} \leq 1/2$, whereas the former predict $\bar{u}/\bar{d} \approx 4/3$. Estimates of valence quark asymmetries based on quark models also show large deviations from SU(3) predictions, which should be measurable.Comment: 15 pages, latex. Figures available from [email protected]. To be published in Phys. Lett.