Predictions for the ${\mathrm{\Lambda }}_b\to J\mathrm{/}\psi \mathrm{\Lambda }(1405)$ decay

We calculate the shape of the $\pi \mathrm{\Sigma }$ and $\bar{K}N$ invariant mass distributions in the ${\mathrm{\Lambda }}_b\to J\mathrm{/}\psi \pi \mathrm{\Sigma }$ and $\Lambda_b \to J/\psi ,\bar K N$decaysthataredominatedbythe$\Lambda(1405)$ resonance. The weak interaction part is the same for both processes and the hadronization into the different meson-baryon channels in the final state is related by SU(3) symmetry. The most important feature is the implementation of the meson-baryon final-state interaction using two chiral unitary models from different theoretical groups. Both approaches give a good description of antikaon-nucleon scattering data, the complex energy shift in kaonic hydrogen and the line shapes of $\pi \mathrm{\Sigma }K$ in photoproduction, based on the two-pole scenario for the $\mathrm{\Lambda }(1405)$. We find that this reaction reflects more the higher mass pole and we make predictions of the line shapes and relative strength of the meson-baryon distributions in the final state.