Identifying the $\Lambda_b(6146)^0$ and $\Lambda_b(6152)^0$ as $D$-wave bottom baryons

Abstract

We study the $\Lambda_b(6146)^0$ and $\Lambda_b(6152)^0$ recently observed by LHCb using the method of QCD sum rules within the framework of heavy quark effective theory. Our results suggest that they can be interpreted as $D$-wave bottom baryons of $J^P = 3/2^+$ and $5/2^+$ respectively, both of which contain two $\lambda$-mode excitations. We also investigate other possible assignments containing $\rho$-mode excitations. We predict masses of their strangeness partners to be $m_{\Xi_b(3/2^+)} = 6.26^{+0.11}_{-0.14}$ GeV and $m_{\Xi_b(5/2^+)} = 6.26^{+0.11}_{-0.14}$ GeV with the mass splitting $\Delta M = 4.5^{+1.9}_{-1.5}$ MeV, and propose to search for them in future LHCb and CMS experiments.