Prospects for observing the lowest-lying odd-parity $Σ_c$ and $Σ_b$ baryons

Abstract

There exist candidates for the negative-parity states $Λ_{c,b}(1/2^-, 3/2^-)$ consisting of an isospin-zero, spin-zero light diquark $[ud]$ with one unit of orbital angular momentum with respect to a $c,b$ quark. However, there exists only one candidate for the orbital excitations of the $Σ_c(1/2^+)$ and $Σ_c^*(3/2^+)$, and none for the orbital excitations of $Σ_b(1/2^+)$ or $Σ_b^*(3/2^+)$. We extend a previous discussion of odd-parity $Λ_{c,b}$ states and explore some patterns of the odd-parity $Σ_{c,b}$ baryons consisting of a light isospin-one nonstrange diquark $(uu,ud,dd)$ in a state of $L=1$ with respect to the spin-1/2 heavy quark $(c,b)$.