6533b86efe1ef96bd12cb205

RESEARCH PRODUCT

Λb→J/ψKΞdecay and the higher order chiral terms of the meson baryon interaction

subject

description

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