The ${\Lambda }_b\to J/\psi K\Xi$ decay and the higher order chiral terms of the meson baryon interaction

Abstract

We study the weak decay of the ${\Lambda }_b$ into $J/\psi K\Xi$ and $J/\psi \eta \Lambda$ states, and relate these processes to the ${\Lambda }_b\to J/\psi \bar{K}N$ decay mode. The elementary weak transition at the quark level proceeds via the creation of a $J/\psi$ meson and an excited $sud$ system with $I=0$, which upon hadronization leads to $\bar{K}N$ or $\eta \Lambda$ pairs. These states undergo final state interaction in coupled channels and produce a final meson-baryon pair. The $K\Xi$ state only occurs via rescattering, hence making the ${\Lambda }_b\to J/\psi K\Xi$ process very sensitive to the details of the meson-baryon interaction in strangeness $S=-1$ and isospin $I=0$. We show that the corresponding invariant mass distribution is dominated by the next-to-leading order terms of the chiral interaction. The $I=0$ selectivity of this decay, and its large sensitivity to the higher order terms, makes its measurement very useful and complementary to the $K^{-}p\to K\Xi$ cross section data. The rates of the ${\Lambda }_b\to J/\psi K\Xi$ and ${\Lambda }_b\to J/\psi \eta \Lambda$ invariant mass distributions are sizable compared to those of the ${\Lambda }_b\to J/\psi \bar{K}N$ decay, which is measured experimentally, thus, we provide arguments for an experimental determination of these decay modes that will help us understand better the chiral dynamics at higher energies.

Comments: 9 PAGES, 7 FIGURES