X(4260)
The
ψ(4S)
resonance
does
not couple
to
ππJ/ψ
,
but does
couple
strongly to
D
s
*
D
s
*
,
thereby
depleting
the ππJ/ψ signal.
The
threshold enhancement
at the
D
s
*
D
s
*
threshold
is
well visible
in D*D*.
Left:
&psi (4S)→D
s
*
D
s
*
depletes
ππJ/ψ
signal.
Right: D
s
*
D
s
*
threshold enhancement
arXiv:1004.4368
arXiv:1005.1010