Transitions of two baryons to the H dibaryon in nuclei

Abstract

We calculate the suppression in the rate at which two baryons in a nucleus (viz., nucleons or $\Lambda$'s) convert to an H dibaryon, using an Isgur-Karl wavefunction for quarks in the baryons and H, and a Bethe-Goldstone wavefunction for the baryons in the nucleus. If $r_H \lsi 1/3~ r_N$, we find $\tau_{A_{\Lambda\Lambda}\to A'_H}\gsi \tau_\Lambda$ and the observation of $\Lambda$ decays from double-$\Lambda$ hypernuclei does not exclude the existence of the H. If $m_H < 2 m_p$, nuclei are unstable but have very long lifetimes. For reasonable values of $r_H$ and the nuclear wavefunction, the lifetime can be long enough to evade anticipated SuperK limits $\tau_{A_{NN}\to A'_H}\gsi {\rm few} 10^{29}$ yr, or short enough to be observed. An analysis of SuperK data to look for this possibility should be undertaken.