Interpretation of the newly observed ${\Lambda }_b(6146{)}^0$ and ${\Lambda }_b(6152{)}^0$ states in a chiral quark model

Abstract

The strong decays of the low-lying $\lambda$-mode ${\Lambda }_b(1D,2S)$ and ${\Sigma }_b(2S)$ states are studied in a chiral quark model. We find that: (i) the newly observed ${\Lambda }_b(6146/6152)$ resonances in the ${\Lambda }_b{\pi }^{+}{\pi }^{-}$ spectrum by the LHCb Collaboration might be explained with the $\lambda$-mode ${\Lambda }_b(1D)$ states in the quark model. It should be emphasized that whether the structure in the ${\Lambda }_b{\pi }^{+}{\pi }^{-}$ spectrum correspond to two states or one state should be further clarified with more observations in future experiments. (ii) The ${\Lambda }_b(2S)$ $|J^P={\frac{1}{2}}^{+},0⟩$ state mainly decays into ${\Sigma }_b^{\ast }\pi$ channel, which may be an ideal channel for searching for this ${\Lambda }_b(2S)$ state in future experiments. (iii) The ${\Sigma }_b(2S)$ $|J^P={\frac{1}{2}}^{+},1⟩$ and $|J^P={\frac{3}{2}}^{+},1⟩$ dominantly decay into ${\Lambda }_b\pi$ with $\Gamma \simeq 3.82$ MeV and $\Gamma \simeq 4.72$ MeV, respectively.

Comments: 6 pages. arXiv admin note: text overlap with arXiv:1810.02205