Particle Physics Seminar: VERY NARROW EXCITED $\Omega_c$ BARYONS

Abstract:

Recently LHCb reported the discovery of five extremely narrow excited $\Omega_c$ baryons decaying into $\Xi_c^+ K^-$.  We interpret these baryons as bound states of a $c$-quark and a $P$-wave $ss$-diquark. For such a system there are exactly five possible combinations of spin and orbital angular momentum.  The narrowness of the states could be a signal that it is hard to pull apart the two $s$-quarks in a diquark.
We predict two of spin 1/2, two of spin 3/2, and one of spin 5/2, all with negative parity.  We discuss relations among the five masses expected in the quark model and the likely spin assignments and compare with the data.  Detailed experimental tests are proposed to distinguish between this and alternative interpretations of the data.  A similar pattern is expected for negative-parity excited $\Omega_b$ states.

The talk is based on arXiv:1703.07774

Seminar Organizer: Prof. Nissan Itzhaki