The Pentaquark Candidates in the Dynamical Diquark Picture

Abstract

Starting with the dynamical picture of the exotic $c\bar c$-containing states $XY \! Z$ as the confinement-induced hadronization of a rapidly separating pair of a compact diquark and antidiquark, we describe the pentaquark candidates $P_c^+(4380)$ and $P_c^+(4450)$ in terms of a confined but rapidly separating color-antitriplet diquark $cu$ and color-triplet "triquark" $\bar c (ud)$. This separation explains the relatively small $P_c^+$ widths, despite these 5-quark systems lying far above both the $J/\psi \, p$ and $\Lambda_c \bar D^{(*)0}$ thresholds. The $P_c^+$ states are predicted to form isospin doublets with neutral partners $P_c^0$.