Importance of Future Hyperon Beta Decay Experiments

Abstract

Recent results from the KTeV experiment at Fermilab using $\Xi^0$ hyperons have enabled a great leap in improving our understanding of elementary particle physics, especially with the first form-factor measurement from the semi-leptonic decay $\Xi^0 \to \Sigma^+ e^- \bar{\nu}$. This decay is a test of whether the standard model contains all of the needed parameters to fully describe hyperon beta decay. It was observed for the first time only in 1997 even though its importance had been explicitly stated in 1961 by the early theories of the standard model as formulated by N. Cabibbo. We have the ability to improve this measurement substantially by making the definitive form-factor measurement with a sample of 30,000 such decays from a forthcoming experiment, which will either show or rule out the existence any additional second class weak currents, an obviously important measurement allowing particle physics to finally put this question to rest. We also have the ability to make a measurement of hyperon compositeness by measuring the charged $\Sigma^{\pm}$ beta decay into $\Lambda^0$, and in addition to search for mass coupling terms in hyperon beta decays where the muon replaces the electron, important for determining the $g_3$ and $f_3$ form-factors. These are the important questions to answer in studying strange baryon decays, and are reviewed in this article.