Bottom Baryon Decays to Pseudoscalar Meson and Pentaquark

Abstract

Based on SU(3) flavor symmetry, we decompose the decay amplitudes of bottom baryon decays to a pseudoscalar meson and an octet (a decuplet) pentaquark in terms of three (two) invariant amplitudes $T_1$ and $T_{2,3}$ (${\tilde{T}}_1$ and ${\tilde{T}}_2$) corresponding to external $W$-emission and internal $W$-emission diagrams, respectively. For antitriplet bottom baryons ${\Lambda }_b^0,{\Xi }_b^0$ and ${\Xi }_b^{-}$, their decays to a decuplet pentaquark proceed only through the internal $W$-emission diagram. Assuming the dominance from the external $W$-emission amplitudes, we present an estimate of the decay rates relative to ${\Lambda }_b^0\to P_p^{+}{K}^{-}$, where $P_p^{+}$ is the hidden-charm pentaquark with the same light quark content as the proton. Hence, our numerical results will provide a very useful guideline to the experimental search for pentaquarks in bottom baryon decays. For example, ${\Xi }_b^0\to P_{{\Sigma }^{+}}{K}^{-}$, ${\Xi }_b^{-}\to P_{{\Sigma }^{-}}{\bar{K}}^0$, ${\Omega }_b^{-}\to P_{{\Xi }^{-}}{\bar{K}}^0$ and ${\Omega }_b^{-}\to P_{{\Xi }^0}{K}^{-}$ may have rates comparable to that of ${\Lambda }_b^0\to P_p^{+}{K}^{-}$ and these modes should be given the higher priority in the experimental searches for pentaquarks.

Comments: 15 pages, 1 figure; references added, typos corrected