W-exchange contributions in hadronic decays of bottom baryon ${\Lambda }_b$

Abstract

The nonleptonic decays ${\Lambda }_b\to {\Sigma }_c^{\ast -}{\pi }^{+},{\Xi }_c^{\ast 0}{K}^0$ and ${\Lambda }_b\to {\Delta }^0{D}^0,{\Sigma }^{\ast -}{D}_0^{+}$ are studied. In addition, the decays ${\Lambda }_b\to {\Xi }_c^0{K}^0,{\Sigma }^{-}{D}_s^{+}$ are analyzed. For all these decays the dominant contribution comes from $W-$exchange, and for the decay ${\Lambda }_b\to {\Lambda }_c^{+}{\pi }^{-}$, in addition to factorization, baryon pole contribution to the $p$-wave (parity conserving) decay amplitude $B$ is discussed.