1. Heavy quark spin structure in hidden charm molecules
University
Heavy quark spin structure in hidden charm molecules
Yan-Rui Liu
(刘言锐)
Shandong University, Jinan, China
Oct. 29, 2013

2. Content Exotic states and molecular candidates
Heavy quark spin structure in meson-antimeson system
Strong decays into charmonia
Summary

3. Near threshold, coupled channel effects Difficult to understand in QM
Solid: observed
Dashed: QM
Dots: unexpected
Unexpected states:
Above DD threshold
Near threshold, coupled channel effects
Difficult to understand in QM

4. Charged exotic mesons Zb(10610), Zb(10650):
PRL 108, (2012) [Belle]

5. Molecular candidates
Deuteron: a well-known shallow bound state of proton and neutron (6-quark system)
X(3872): a deuteron-like molecule?
Y(4260): a molecule?
Charged quarkonium-like mesons: explicitly exotic.
Meson-antimeson molecule or tetraquark
candidates!
Z(3900): a charged molecule?

6. Molecular candidates So many heavy quark meson-antimeson thresholds
More near-threshold exotic states and molecule candidates are expected
Study its structure from cc spin, 1 or 0?
(In the limit mQ: the cc spin is conserved in strong decays)
In what case the spin is only 1?

7. Meson-antimeson spin structure
Voloshin, PLB 604, 69 (2004).
X(3872) as a C= molecule: only
X(3872) suppressed
Other S-wave meson-antimeson states
HQ limit:
Heavy quark spin selection rule

8. Meson-antimeson spin structure
Approach: Construct spin wave function
 recouple spin wave function
 extract information for
Y.R. Liu, PRD 88, (2013)

9. Meson-antimeson spin structure
: spin wavefunction of the pair
[......]: state with and :
(1) A=B
(2) AB but the same doublet (A, B)

10. Meson-antimeson spin structure
AB but the same
doublet (A, B)
A=B
Consistent with
General case: AB

11. HQS selection rules
when
(a)
(b) if (A,B) is a doublet

12. HQS selection rules (cqq)-baryon doublets (two) singlets: L=0 & L=1
Baryon-antibaryon case:
Adoublet, Bdoublet: same selection rules Asinglet, Bdoublet: same selection rules
Asinglet , Bsinglet:

13. Strong decays into charmonia
X(3872) Not observed Zc(3900) Not observed
A tetraquark?

14. Strong decays into charmonia
A charged state in hc  J=1, c! J/?
A charged state in J/?  c: J=0 or 2

15. Summary
Two selection rules for in S-wave meson-antimeson states in HQ limit:
(a)
(b) if (A,B) is a doublet
(Similar rules for S-wave baryon-antibaryon states )
Heavy quark limit: conserved in strong decays of hadron-antihadron states
HQS violated ...
Thank you!