Direct Quark Mechanism for Weak $\text{Lam}N\leftrightarrow NN$ Processes

Abstract

Two body weak processes $\Lambda N\leftrightarrow NN$ are studied from the viewpoint of quark substructure of baryons.They can be studied in nonmesonic weak decays of hypernuclei and also hyperon production in the $NN$ scattering. The direct quark mechanism in contrast to the one-pion exchange mechanism is shown to give sizable $\text{di}=3/2$ contribution in the J=0 channel. Nonmesonic decay rates of ${}_{\Lambda }^4$H, ${}_{\Lambda }^4$He, and ${}_{\Lambda }^5$He agree with the current experimental data fairly well. Especially the $n/p$ ratio is enhanced by the direct quark contribution. The cross sections for $pn\to \text{Lam}p$ scattering are studied in the quark cluster model approach.

Comments: 7 pages, 3 figures (eps)