Interpretation of excited ${\Omega }_b$ signals

Abstract

Recently LHCb reported the discovery of four extremely narrow excited ${\Omega }_b$ baryons decaying into ${\Xi }_b^0{K}^{-}$. We interpret these baryons as bound states of a $b$-quark and a $P$-wave $ss$-diquark. For such a system there are exactly five possible combinations of spin and orbital angular momentum. We predict two of spin 1/2, two of spin 3/2, and one of spin 5/2, all with negative parity. We favor identifying the observed states as those those with spins 1/2 and 3/2, and give a range of predicted masses for the one with spin 5/2. We update earlier predictions for these states based on the five narrow excited ${\Omega }_c$ states reported by LHCb. An alternative picture of the states in which one of $J=1/2$ is extremely wide and hence not seen by LHCb is discussed.

Comments: 12 pages, 1 figure. Version including proof corrections to be published in Phys. Rev. D