Is d＊ a candidate for a hexaquark-dominated exotic state

We confirm our previous prediction of a d＊ state with I（JP） = 0（3＋） [Phys. Rev. C 60, 045203（1999）] and report for the first time based on a microscopic calculation that d＊ has about 2/3 hidden color（CC）configurations and thus is a hexaquark-dominated exotic state. By performing a more elaborate dynamical coupledchannels investigation of the △△-CC system within the framework of the resonating group method（RGM） in a chiral quark model, we find that the d＊ state has a mass of about 2.38-2.42 Ge V, a root-mean-square radius（RMS） of0.76-0.88 fm, and a CC fraction of 66%-68%. The last may cause a rather narrow width for the d＊ which, together with the quantum numbers and our calculated mass, is consistent with the newly observed resonance-like structure（M ≈2380 Me V, Γ≈70 Me V） in double-pionic fusion reactions reported by the WASA-at-COSY Collaboration.