Search for $XYZ$ states in ${\Lambda }_b$ decays at the LHCb

Abstract

We consider $X(3872)$ and $Y(4140)$ as the vector tetraquark states of $X_c^0\equiv c\bar{c}u\bar{u}(d\bar{d})$ and $c\bar{c}s\bar{s}$, respectively. By connecting ${\Lambda }_b\to X_c^0\Lambda$ to $B^{-}\to X_c^0{K}^{-}$, we predict that the branching ratios of ${\Lambda }_b\to \Lambda (X(3872{)}^0\to )J/\psi {\pi }^{+}{\pi }^{-}$ and ${\Lambda }_b\to \Lambda (Y(4140)\to )J/\psi \varphi$ are $(5.2\pm 1.8)\times 10^{-6}$ and $(4.7\pm 2.6)\times 10^{-6}$, which are accessible to the experiments at the LHCb, respectively. The measurements of these ${\Lambda }_b$ modes would be the first experimental evidences for the $XYZ$ states in baryonic decays.

7 pages, 1 figures