2 00 9 Channel coupling in heavy quarkonia : energy levels , mixing , widths and new states

Channel coupling via decay products is developed to describe energy shifts, level mixing as well as the possibility of new resonances in c¯ c, b ¯ b systems. The new ingredients involve: 1) the Weinberg eigenvalue method to describe coupled-channel resonances and wave functions in a unitary way; 2) the pair creation vertex, derived nonperturbatively, having the 3 P 0 form with calculable coefficient; 3) relativistic as well as nonrelativistic decay matrix elements are constructed; 4) conditions for creation of new states due to channel coupling are formulated; 5) realistic wave functions for all resonances. Theoretical methods used in the paper do not contain fitting parameters and are checked vs experiment. Examples of level shifts, widths and mixing are presented. Two peaks in the 3 P 1 state are found: one narrow at 3.872 GeV and another around 3.935 GeV with width Γ ≈ 30 MeV.