Pion-Assisted Nδ and Nδ dibaryons∗

Nδ and δδ dibaryon candidates are discussed and related quark-based calculations are reviewed. New hadronic calculations of L = 0 nonstrange dibaryon candidates are reported. For Nδ, I(JP) = 1(2+) and 2(1+) S-matrix poles slightly below threshold are found by solving pNN Faddeev equations with relativistic kinematics, and for δδ several S-matrix poles below threshold are found by solving pNδ Faddeev equations with relativistic kinematics in which the Nδ interaction is dominated by the 1(2+) and 2(1+) resonating channels. In particular, the I(JP) = 0(3+) δδ dibaryon candidate D03(2370) observed recently by theWASA@COSY Collaboration is naturally explained in terms of long-range physics dominated by pions, nucleons and δ's. These calculations are so far the only ones to reproduce the relatively small width ≈70 MeV of D03(2370). Predictions are also made for the location and width of D30, the I(JP) = 3(0+) exotic partner of D03(2370).