Heavy quark spin selection rules in meson-antimeson states

In the heavy quark limit, we discuss the spin of the charm-anticharm pair J(c (c) over bar) in an S-wave meson-antimeson molecule or resonance. One finds two cases in which J(c (c) over bar) cannot be 0: (a) J = vertical bar j(2) - j(4)vertical bar - 1 of J = j(2) + j(4) + 1, where J is the total spin of the system and j(2) (j(4)) is the total angular momentum of the light degree of freedom in a charmed meson (antimeson); and (b) J(C) 1(+), 2(-), 3(+),..., if the two different mesons belong to the same doublet. The decays to spin-singlet charmonium states are suppressed when one of the two conditions is satisfied. We discuss constrained decay properties for selected systems.