X(4260)
     
     
The ψ(4S) resonance
does not couple to ππJ/ψ,
but does couple strongly to Ds*Ds*,
thereby depleting the ππJ/ψ signal.
The threshold enhancement
at the Ds*Ds* threshold
is well visible in D*D*.

  Left:   &psi (4S)→Ds*Ds* depletes ππJ/ψ signal.

  Right:   Ds*Ds* threshold enhancement

  arXiv:1004.4368
  arXiv:1005.1010