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Possible Interpretations of D sJ (2632)

Possible Interpretations of D sJ (2632). Shi-Lin Zhu Peking University QWG2004 October 14, 2004 Collaborators: Y.-B. Dai, C. Liu, Y.-R. Liu Hep-ph/0407157 (PRD in press) Hep-ph/0408234. 1. Advances in Hadron Spectroscopy Since 2003.

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Possible Interpretations of D sJ (2632)

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  1. Possible Interpretations of DsJ(2632) Shi-Lin Zhu Peking University QWG2004 October 14, 2004 Collaborators: Y.-B. Dai, C. Liu, Y.-R. Liu Hep-ph/0407157 (PRD in press) Hep-ph/0408234

  2. 1 Advances in Hadron Spectroscopy Since 2003 • BES:pp_bar near-thresholdenhancement in J/Psigamma pp_bar decays, I=0 channel; p Lambda_bar threshold enhancement in J/Psi K p Lambda_bar • BABAR/CLEO/BELLE: narrow states DsJ(2317), DsJ(2457) below threshold • LEPSand othersfound evidence ofPentaquarks! • BELLE/CDFII: new narrow state X(3872) • E852: two exotic mesons with JPC=1-+at1709/2001MeV • SELEX: narrow state DsJ(2632) above threshold with abnormal decay pattern

  3. 2 SELEX observed DsJ(2632) inDs+ eta and D0K+ modes 2+ state in (1+, 2+) doublet in HQET 49.3 events 14 events 7.2 sigma 5.3 sigma

  4. 3 BABAR, CLEO, FOCUS didn’t see DsJ(2632)

  5. SELEX: fixed-target hadroproduction 600 GeV Sigma- beam which consists strange quark explicitly looks at very large Xf, not available for e+e- colliders Production: gluon-gluon fusion BABAR/CLEO: e+e- colliders , center of mass close to Upsilon Production: e+e- annihilation FOCUS: photoproduction doesn't see double-charm hadrons but they exist! 4 Non-observation of a particular state in certain experiments does not exclude its possible existence The production ratios of different charm states could be quite different between e+e- annihilation and gluon-gluon fusion According to Evdokimov at SELEX: If DsJ(2632) really exists Special mechanism in hadroproduction at large Xf

  6. 5 Three Puzzles of DsJ(2632) If Not Artifact • Narrow decay width. 274 MeV above D0K+and 116 MeV above Ds eta threshold, decay width less than 17 MeV. Naive expectation around (100~200) MeV • Is DsJ(2632) a cs_bar state? L=0: [Ds(1968), D*s(2112)] L=1, lP=1/2+:[DsJ(2317), DsJ(2457)] L=1, lP=3/2+:[DsJ(2536), DsJ(2573)] Too low for L=2 assignment Is it the first radial excitation of D*s(2112)? (K.-T. Chao) • Unusual decay pattern SU(3)F symmetry + cs_bar assignment SELEX

  7. 6 DsJ(2632) As a Tetraquark Version I:(Liu, Zhu, Dai, Liu) • 0+ isoscalar member in 15 rep., the ratio of SU(3) C-G coefficients naturally explains its anomalous decay pattern: • Quark content: • Mass: • Decay pattern: SU(3) C-G Decay Momentum

  8. 7 Weight Diagram of Heavy Tetraquark Multiplets

  9. 8 Version II:(Chen, Li; Gupta) • Quark content:  fluctuates into Hence main decay mode is • D0K+ requires  , component, OZI suppressed

  10. 9 Version III:(Chao) • Tightly bound diquark configuration which has small mixing with ,  narrow total width • Mixing between  unusual decay pattern Version IV:(Maiani;Nicolescu) • Quark content: • D0K+ suppressed while important • Decay pattern: • Prediction:

  11. 10 Problems With Tetraquark Scheme • There should be many other tetraquark partners of DsJ(2632). Where are they? • Its narrow width may require that quarks inside DsJ(2632) form tightly bound clusters like diquarks. Otherwise tetraquarks fall apart easily. • The first three versions of tetraquarks predict the same production rates for D+K0, D0K+ final states. The fourth version predicts very large D+K0 mode. • But SELEX didn't find any signal in the D+K0 channel!

  12. 12 DsJ(2632) as Radial Excitation • First radial excitation of Ds(2112) with JP=1- (Chao; Barnes et al.;Bereven, Rupp) • The nodal structure of its radial wave function ensures the narrow total width • Different decay momentum in two channels leads to anomalous decay pattern • Dynamical calculation very desirable and missing Future experimental search for: (Dai, Liu, Liu, Zhu) • its SU(3) flavor partners DJ0,+(2530) • its B-meson analogues BJ0,+(5840), BsJ+(5940) • S-wave two pion decay modes

  13. In the large Nc limit, the dominant decay mode is for the gluon to split into a color-octet recombines with pair to form The Nc order of this decay amplitude is No abnormal decay pattern as observed in SELEX  This assignment not preferred! 13 Large Nc And DsJ(2632) As A Hybrid Meson: Version I(Dai, Liu, Liu, Zhu)

  14. Decay mode (b) into glueball is dominant, Nc0, forbidden by kinematics The subleading mode (c) into becomes dominant; is mixture of and  Ds eta dominant D0K+ can occur via mode (a) c s_bar is color-singlet, additional 1/Nc suppression from color mismatch, its Nc order 14 Version II:Hybrid Scheme (Dai, Liu, Liu, Zhu) But its mass and decay width needs dynamical calculation!

  15. 15 Summary • SELEX observed DsJ(2632) but BABAR, CLEO, FOCUS didn’t see it. • It could be an artifact. • If it really exists, it could be - Tetraquark - Radial excitation - Heavy hybrid meson - …

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