SU(3) Breaking in Hyperon Beta Decays: a Prediction for Xi0 -> Sigma+ e anti-neutrino

SU(3) breaking in hyperon semi-leptonic decays is discussed. The SU(3) parameters $F$ and $D$, relevant to the ``proton-spin puzzle'', are extracted and a prediction is presented for the decay Xi0 -> Sigma+ e anti-neutrino, currently under study by the KTeV collaboration. The values found are g1/f1 = 1.16+/-0.03+/-0.01 and Gamma = (0.80+/-0.03+/-0.01) x 10^6 s^-1.Comment: Presented at the III Int. Conf. on Hyperons, Charm and Beauty Hadrons (Genova, June-July 1998). 3 pages, LaTeX2e, uses fleqn, espcrc2, acromake and axodraw packages (incl.

Complements of tori and Klein bottles in the 4-sphere that have hyperbolic structure

Many noncompact hyperbolic 3-manifolds are topologically complements of links in the 3-sphere. Generalizing to dimension 4, we construct a dozen examples of noncompact hyperbolic 4-manifolds, all of which are topologically complements of varying numbers of tori and Klein bottles in the 4-sphere. Finite covers of some of those manifolds are then shown to be complements of tori and Klein bottles in other simply-connected closed 4-manifolds. All the examples are based on a construction of Ratcliffe and Tschantz, who produced 1171 noncompact hyperbolic 4-manifolds of minimal volume. Our examples are finite covers of some of those manifolds.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol5/agt-5-41.abs.htm