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The mechanism of channel coupling via decay products is used to study energyshifts, level mixing as well as the possibility of new near-thresholdresonances in $c\bar c, b\bar b$ systems. The Weinberg eigenvalue method isformulated in the multichannel problems, which allows to describecoupled-channel resonances and wave functions in a unitary way, and to predictnew states due to channel coupling. Realistic wave functions for allsingle-channel states and decay matrix elements computed earlier are exploited,and no new fitting parameters are involved. Examples of level shifts, widthsand mixings are presented; the dynamical origin of X(3872) and the destiny ofthe single-channel $2^3P_1(c\bar c)$ state are clarified. As a result a sharpand narrow peak in the state with quantum numbers $J^{PC}=1^{++}$ is found at3.872 GeV, while the single-channel resonance originally around 3.940 GeV,becomes increasingly broad and disappears with growing coupling to openchannels.

Channel coupling in heavy quarkonia: energy levels, mixing, widths and new states