Transcript The oddball Y(4140) as the cousin of Y(3930) Xiang Liu Lanzhou University

The oddball Y(4140) as the
cousin of Y(3930)
Xiang Liu
[email protected]
School of Physical Science and Technology
Lanzhou University
Xiang Liu & S. L. Zhu, Phys.Rev.D80, 017502 (2009)
Xiang Liu, Z. G. Luo, Y. R. Liu and S. L. Zhu,
Eur.Phys.J.C61:411-428 (2009)
Xiang Liu, Phys.Lett. B680, 137-140 (2009)
Xiang Liu & H.W. Ke, Phys.Rev.D80, 034009 (2009)
QNP09 October 21-25 2009, at IHEP, China
CDF experiment observed Y(4140)
See Phys.Rev.Lett.102:242002,2009
Y (4140)
M  4143.0  2.9  1.2 MeV
+8.3
 =11.7-5.0
 3.7 MeV
Y(4140)
C parity: +
G parity: +
Charmonium  like states:
X (3872) X(3930)/Y(3930)/Z(3930) Y(4260) Z (4430)
B   J / K
Belle Collaboration
Phys.Rev.Lett.94:182002 (2005)
BaBar Collaboration
Phys.Rev.Lett.101: 082001 (2008)
BELLE
M  3943  11( stat )  13( syst ) MeV =87  22(stat)  26(syst) MeV
BABAR
+12
M  3914.63.8
3.4 ( stat )  2.0( syst ) MeV  =34 -8 ( stat )  5( syst ) MeV
The similarities between Y(4140) and Y(3930)
 Both Y(4140) and Y(3930) were observed in the mass spectrum
of J/ +light vector meson
J/  Y (4140)
B  K+
J/  Y (3930)
 The mass difference between Y(4140) and Y(3930) approximately equal to
that between  and 
M Y(4140)  M Y (3930)  M   M 
 Y(4140) and Y(3930) are close to the thresholds of D*s D*s and D* D* , and satisfy an
almost exact mass relation
M Y(4140)  2 M D*  M Y (3930)  2 M D* = - 90 MeV
s
What is the structure for Y(4140)?
Y (4140) is a D*s D*s molecular state while Y(3930) is its D*D* molecular partner
Wavefunction
Select rule
 The possible quantum numbers of the S-wave vector-vector system are
J P  0 ,1 , 2.
 However for the neutral D*D* system with C=+, we can have
J P  0 , 2 since C=(-1) L  S and J=S with L=0.
Effective Potential
For details, see Xiang Liu, Z. G. Luo, Y. R. Liu, S.L. Zhu,
Eur.Phys.J.C61:411-428,2009
The shape of the potential of Y(4140) and Y(3930)
Decay Patterns of Y (4140) and Y (3930)
Hidden charm two-body decay
 The discovery mode of Y(3930) and Y(4140)
 This S-wave decay occurs via the rescattering mechanism
 Hidden charm decay is strongly suppressed for the conventional
excited charmonium around 4 GeV.
 This mode is not sppressed for heavy molecular states.
Sometimes, they become one of the dominant decay modes.
Open charm two-body decays
S-wave
D-wave
The open-charm decay widths
are comparable to the
hidden-charm decay width
Such a D-wave decay width
should be much smaller than
that for the above hidden
charm S-wave decay mode!
 Open charm three-body and four-body decays
Y(3930):
D* D , DD
Xiang Liu & H.W. Ke
Y(4140) :
D*s DK , DKDK
Phys.Rev.D80, 034009 (2009)
D*s Ds , Ds Ds (isospin violating modes)
Kinematically Forbidden !!!
 Radiative decay
Y(3930): D*D , D D , D D
Y(4140): D*sDs , Ds Ds , Ds Ds
The radiative decay width and the line shape of the photon
spectrum are very interesting
 Semi-leptonic and Non-leptonic decay
The semi-leptonic and non-leptonic decays via one component
of the molecular state also contain useful information of its
inner structure.
Summary
We proposed a uniform molecular state assignment for Y(4140) and Y(3930)
Y (4140) is a D*s D*s molecular state while Y(3930) is its D*D* molecular partner
Find a select rule for the quantum nubmer of Y(4140) and Y(3930) in the molecular picture
J P  0 , 2
Their hidden-charm decay, open-charm decay, radiative decay
are important and interesting to test molecular state assignment
for Y(4140) and Y(3930).
Confirming Y(4140) in other experiments is important. Belle
and Babar experiments.
We suggest the measurment of the line shape of the
photon spectrum of the radiative decay of Y(4140) and
Y(3930).
Thank you for your attention !
Backup slides
Charmonium
• Y (4140) lies well above the open charm decay threshold.
• Charmoniums with this mass would decay into an open charm pair dominantly.
• The branching fraction of its hidden charm decay mode
is expected to be
J /
tiny.
4
3
BR 10  10
(see Xiang Liu, arXiv:0904.0136 [hep-ph])
Thus, both the narrow width of Y (4140) and its large hidden charm decay
pattern disfavor the conventional charmonium interpretation.
Tetraquark state
ccs s
The simple chromo-magnetic interaction:
[see Y. Cui, X. L. Chen, W. Z. Deng, S.L. Zhu, HEP&NP 31, 7 (2007)]
J P = 0+ , 1+ M= 4.1 GeV
J P = 2+
unbound
Hybrid state
• Tetraquarks will fall apart into
a pair of charmed mesons
very easily.
• As a tetraquark, the width of
Y (4140) would be around
several hundred MeV
instead of 12 MeV as
observed by CDF.
A partner of Y(4260) within the same
J P  1 hybrid charmonium family
The B meson decay process
does not provide a glue-rich
environment as in the
Upsilon/charmonium annihilation.
So the possibility of Y (4140)
being a hybrid state is small.
(1) the narrow width of Y(4140) < the width of Y(4260)
(2) the different decay patterns of Y(4140) and Y(4260)
J/
J/  -
J/ K  K -
(3) the similarity between Y(4140) and Y(3930)