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

Advances in Hadron Spectroscopy Since 2003 1 Advances in Hadron Spectroscopy Since 2003 BES: pp_bar near-threshold enhancement 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 LEPS and others found evidence of Pentaquarks! BELLE/CDFII: new narrow state X(3872) E852: two exotic mesons with JPC=1-+ at 1709/2001MeV SELEX: narrow state DsJ(2632) above threshold with abnormal decay pattern

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

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

Non-observation of a particular state in certain 4 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! 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

Three Puzzles of DsJ(2632) If Not Artifact 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

DsJ(2632) As a Tetraquark Version I: (Liu, Zhu, Dai, Liu) 6 SU(3) C-G 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

Weight Diagram of Heavy Tetraquark Multiplets 7 Weight Diagram of Heavy Tetraquark Multiplets

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

Version IV: (Maiani;Nicolescu) 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:

Problems With Tetraquark Scheme 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!

DsJ(2632) as Radial Excitation 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 BJ 0,+(5840), BsJ+(5940) S-wave two pion decay modes

13 Large Nc And DsJ(2632) As A Hybrid Meson: Version I (Dai, Liu, Liu, Zhu) 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!

Version II: Hybrid Scheme (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 But its mass and decay width needs dynamical calculation!

Summary SELEX observed DsJ(2632) but BABAR, CLEO, FOCUS didn’t see it. 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 - …