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Hadron spectroscopy at Belle

Hadron spectroscopy at Belle. J olanta Brodzicka (Krakow) Hadron Workshop, Nagoya 6-7 December 2008. Belle at KEKB. KEKB: a symmetric e + e - collider e + : 3.5 GeV  e - : 8.0 GeV √s= 10.58 GeV =  (4S) mass e + e -  (4S)  B B Operating since 1999

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Hadron spectroscopy at Belle

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  1. Hadron spectroscopy at Belle Jolanta Brodzicka (Krakow) Hadron Workshop, Nagoya 6-7 December 2008

  2. Belle at KEKB • KEKB:asymmetric e+e- collider e+: 3.5 GeV  e-: 8.0 GeV √s=10.58 GeV = (4S) mass e+e-  (4S)  BB • Operating since 1999 • Peak luminosity: 1.711034cm-2s-1 • Integrated luminosity: 860 fb-1 750 fb-1 @ (4S) ~ 780 * 106 BB ~ 960 * 106 cc Beauty and Charm Factory

  3. History of spectroscopy at Belle X(3872) Z(3930) Ξc(3077) Ξc(2980) Z+(4430) Y(3940) D*0 D*2 DsJ(2700) 2002: ηc’→KsKπ X(3872) →J/ψπ+π- D*0(2308)→Dπ and D1’(2420)→D*π properties of D*s0(2317) and Ds1(2460) Y(3940)→J/ψω Z(3930)=χc2’→DD X(3940)→DD* Ξc(2980) Ξc(3077)→ΛcKπ Y family→ψ(1S,2S)π+π- DsJ+(2700) →D0K+ X(4260)→DD* Z+(4430)→ψ(2S)π+ Z+(4051) Z+(4281)→χc1π+ 2008: Yb(?)→Yπ+π- cc-like XYZ states : exotics? I will focuse on them

  4. Conventional vs exotic states q q q q q • Quark Model by Gell-Manna and Zweiga (1964): (qq) mesons and (qqq) baryons = conventional states • QCD based potential models → hadron masses, decays,... Observed cc multiplets agree with the models’ predictions • States more complex than qq or qqq =exotics also predicted by the models • cc spectrum „cleaner” than uu/dd/ss → cc-like exotics easier to identify 2M(D)

  5. Menu of cc-like exotics c g q c c q c q c π q c D D(*) • Hybrids: cc+ excited gluon(excited flux-tube) • Lattice QCD: lightest hybrids @ 4.2GeV • Exotic quantum numbers JPC= 0+-, 1-+, 2+-… • Γ(H→DD**)> Γ(H→DD(*) ) • Large Γ(H→ψππ, ψω,… ) • Tetraquarks: diquark-antidiquark [cq][cq] • Tightly bound diquarks (gluon exchange) • Decay:„coloured” quarks rearrange into „white” mesons → dissociation • Molecules: M(cq)M(cq) • Meson and antimeson loosely bound (pion exchange) • Decay: dissociation into constituent mesons • How to identify exotic cc hadron? • JPC forbidden for conventional cc • Final states with non-zero electric charge and/or strangness: • J/ψπ- =(cc)(ud) Ds+D- =(cs)(cd) • Too small/large rates in some decay modes

  6. Recently observed cc-like states

  7. Production of ccin B Factory b c u, dc s u, d c γ* c c c e+ J/ψ X e- BX=ηcχcψ… W K e+ e+ e- e- γ γ γISR γ* X π π ψ D D X e+ e- • double cc production • e+e-→J/ψXcc • γγ collision • e+e-→γγ→Xcc→DD • B meson decays: B→XccK(BF~10-3) • initial state radiation (ISR) e+e-→γISRXcc→γISRψππ Good experimental environment to search for new resonances JPC(X)=0++, 0-+ J(X)=0, 2 C(X)=+1 JPC(X)=1--

  8. Observation of Z+(4430)→ψ’π+ Mbc ΔE M=4433±4±2MeV Γ=45 MeV +18 +30 –13 -13 ??? Z+(4430) M2(ψ’π+) N=121±30 (6.5σ) K2*(1430) K*(890) M(ψ’π+) M2(Kπ+) PRL100, 142001 (2008) • Study of B→ψ’π+K using 657M BB • ψ’→e+e-, μ+μ-, J/ψπ+π- • after • K* veto Too low statistic to determine JP • First charged cc-like state!Must be exotic! • Proposed interpretations: • [cu][cd] tetraquark;neutral partner in ψ’π0 expected • D*D1(2420)molecule;should decay to D*D*π

  9. No significant Z+(4430) in Babar hep-ex/0811.0564 • B→ψ’π+K studied using413/fb • Mass spectra corrected for efficiency

  10. B→ψ’π+KDalitz plot analysis A B C D E A B C D E M2(ψ’π+) A+C+E =K*veto M2(K-π+ ) M2(ψ’π+) M2(ψ’π+) • B→ψ’π+K amplitude: coherent sumof Breit-Wigner contributions • Maximum likelihood fit to Dalitz plot • Models: all known K*→Kπ+ resonances only all known K*→Kπ+ resonances and Z→ψ’π+favored by data Z+(4430) confirmed Significance: 6.4σ Fit CL: 36%

  11. B0→χc1π+K- study. More Z’s ΔE M(J/ψγ) ??? M2(χc1π+) K2*(1430) K*(1680) K*(892) K0*(1430) K3*(1780) M2(K-π+ ) PRD 78, 072004 (2008) • Dalitz-plot analysis of B0→χc1π+K- χc1 →J/ψγwith 657M BB • B0→χc1π+K- amplitude: coherent sum • of Breit-Wigner contributions • Maximum likelihood fit performed • Models tried: • known K*’s→Kπ only • K*’s + one Z→χc1π+ • K*’s + two Z states : favored by data

  12. Z+1,2→χc1π+ exotic states • Model with two Z’s significantly favored by data • Spin of Zstatesnot determined: spin 0 and 1givesimilarfit qualities M(χc1π+) for 1<M2(K-π+)<1.75GeV –̶̶̶̶̶̶ –̶̶̶̶̶̶fit for null model –̶̶̶̶̶̶ –̶̶̶̶̶̶fit for double Z model –̶̶̶̶̶̶ –̶̶̶̶̶̶Z1 contribution –̶̶̶̶̶̶ –̶̶̶̶̶̶Z2 contribution Non-zero charge suggests multiquark interpretation of Z1 and Z2

  13. cc-like example: X(3872) 152M BB M(J/ψπ+π-) M(π+π-) 117MBB PRL91, 262001 (2003) • X(3872)→J/ψπ+π- observed in B+→X(3872)K+ by Belle • Confirmed by BaBar, CDF, D0 • mX=3871.2±0.5MeVmX-(mD*0+mD0)=-0.6±0.6MeVΓ<2.3MeV • M(π+π-) suggests X(3872)→J/ψρ (S- or P-wave) • Other decay modes: J/ψγ,ψ(2S)γ, J/ψω, DD*, no X→DD • JPC= 1++,2-+favored (from angular analysis by CDF, M(π+π-),decay modes)

  14. What is X(3872) ? M(J/ψπ-π0) • cc? No obvious assignment • D0D*0 molecule? Non-trivial line shape Γ(X→DD*)>Γ(X→J/ψππ) Production in B0 suppressed in regard to B+ • 4-quark? Xu[uc][uc] Xd[dc][dc] Different mass of X produced in B0 and B+ Finding charged X is critical (no evidence so far) Braaten et al. hep-ph/0710.5482 PRD71, 031501 (2005) Maiani, Polosa et al. PRD 71, 014028 (2005)

  15. X(3872)in B+vs B0 decays B0→XK0 Ns=30±7 (6.5σ) B+→XK+ Ns=125±14 (12σ) First observation! 657MBB M(J/ψπ+π-) M(J/ψπ+π-) hep-ex/0809.1224 • Study of X(3872)→J/ψπ+π-inB+→XK+ and B0→XK0s • Similar properties of X(3872) from B+ and B0 decays

  16. X(3872)→D0D*0 (?) N=33±7 (4.9σ) PRD77, 011102(2008) B KD0D*0 D*→Dγ M(X)=3875.1+0.7-0.5 ±0.5MeV Γ=3.0+1.9-1.4 ± 0.9 MeV Preliminary D*→D0π0 605 fb-1 Flatte vs BW similar result: 8.8σ • X(3872)→D*0D0in B+→D*0D0K • New Belle M(X) measurement ruled out • scenario oftwo states: X(3872)→J/ψππand X(3875)→D*D hep-ex/0810.0358 M(X)=3872.6+0.5-0.4±0.4MeV Γ=3.9+2.5-1.3+0.8-0.3 MeV Maiani, Polosa et al. hep-ph/0707.3354 Xu[uc][uc]→D0D0π0= X(3875) Xd[dc][dc]→ J/Ψππ = X(3872)

  17. X(3940) and X(4160) in e+e-→J/ψXcc c γ* c c c e+ J/ψ X e- ee→J/ψDD* X(3940) 6.0σ ee→J/ψD*D* X(4160) 5.5σ M=4156 ± 15 MeV =139 ± 21 MeV +25 –20 M =3942 ± 6 MeV =37 ± 12 MeV +7 –6 M(D*D) M(D*D*) +111 – 61 +26 –15 PRL100, 202001 (2008) • x-sections much larger than QCD predicted → factory of 0++ and 0-+ charmonia • Search for X→DD* and D*D* ine+e-→J/ψD(*)D* • Possible assignments: ηc(3S) ηc(4S) (but X masses ~100-150MeV above predictions for ηc’s) CX=+1 so X(4160)≠ψ(4160)

  18. Y family through ISR M=4259 ± 8 MeV =88 ± 23 MeV +2 –6 +6 –4 γISR γ* π π ψ Y e+ e- PRL 95, 142001 (2005) for 232fb-1 PRL 98, 212001 (2007) for 298fb-1 • ISR gives access to JPC=1-- states • Hard photon emission suppressed, • ‘compensated’ by high luminosity of B-factory Y(4260)→J/ψππ M=4324 ± 24 MeV =172 ± 33 MeV Y(4360)→ψ’ππ PRD74, 091104 (2006) PRL 96, 162003 (2006) for 13pb-1@4.26GeV

  19. 1 - - Y→ψππ states via ISR e+e-→p+p-J/y • Y(4008), Y(4260), Y(4360), Y(4660) • More 1– states than empty slots in cc spectrum Unusual properties: • Large widths for ψππ transition: unlike for conventional cc • Above DD threshold but don’t match the peaks in D(*)D(*) x-sections Other options: • DD1 or D*D0 molecules • cqcq tetraquarks • ccg hybrid: DD1decay mode should dominate • Coupled-channel effects • Charm-meson threshold effects Y(4260) Y(4008) e+e-→p+p-y’ Y(4360) Y(4660)

  20. Exclusive x-sections with ISR PRD77,011103(2008) DD ? DD* (4160) Y(4350) PRL98, 092001 (2007) Y(4008) D*D* Y(4260) (4415) (4040) PRL100,062001(2008) Y(4660) DDπ arXiv:0807.4458 Λc+Λc– NEW PRD 77, 011103 (2008) for 673fb-1 PRL 98, 092001 (2007) for 548fb-1 • Difficult interpretation in terms of resonances (model dependent coupled-channel and threshold effects…) PRL 100, 062001 (2008) for 673fb-1

  21. cc (-like) state of art Y(3360), Y(3660) ηc(4S) • We have observed a few new states • Most of them don’t match cc spectrum

  22. bbanalog of Y(4260)? PRL100, 112001(2008) • If bb follows the ccpattern: Yb→Y(nS)ππ with large partial width • Study of Y(mS)→Y(nS)π+π-with dataat Y(5S)~10.87GeV(21.7/fb) • Energy scan around Y(5S) (7.9/fb) • Large Γ(Y(5S)→Y(nS)ππ)! For other bb states: Γ~O(keV) • Is it Yb? Mixture of Y(5S) and Yb? Observed shape disagree with Y(5S) hypothesis (fit). Yb at 10.89GeV?

  23. Summary • New charmonium spectroscopy @4GeV • Candidates for exotic hadrons observed: Z+(4430)→ψ’π+Z+(4050), Z+(4248)→χc1π+ • Many other states await understanding X(3872) Y(3940) Y-family… • Yb? New spectroscopy also in b quark sectors? • Theory input needed (models to verify, threshold effects, coupled channel effects)

  24. Backup

  25. J. Brodzicka @ PIC08

  26. J. Brodzicka @ PIC08

  27. X(3872)→D0D*0 (?) N=24±6 (6.4σ) N=33±7 (4.9σ) PRD77, 011102(2008) M(X)=3875.1+0.7-0.5 ±0.5MeV Γ=3.0+1.9-1.4 ± 0.9 MeV • Belle: B+→D0D0π0K(447MBB) BaBar: B+→D*0D0K (383MBB) • Mass ~4σ above M(X) for X→J/ψππ • Is this X(3872) or are theretwo states X(3872) and X(3875)? • More precise measurement of mass/width/line shape needed PRL97, 162002(2006) M(X)=3875.4± 0.7+0.4-1.7 ±0.9MeV Xu[uc][uc]→D0D0π0 = X(3875) Xd[dc][dc]→ J/Ψπ+π- = X(3872) Maiani, Polosa et al. hep-ph/0707.3354

  28. Y(3940)→J/ψω K*’s Y(3940) M(ωJ/ψ) M(ωJ/ψ) M2(ωJ/ψ) M2(ωK) Belle PRL 94, 182002 (2005) Babar hep-ex/0711.2047 submitted to PRL • Study of B→ KJ/ψωω→π+π-π0 • Mbc, ΔE and M(π+π-π0) selection mass/width discrepancy needs further study • Y(3940) above DD threshold but has large cc transition • Candidate for cc-gluon hybrid?(but hybrids predicted >4GeV) • Re-scattering DD*→J/ψω? BF(B→KY)*BF(Y→J/ψω)= Belle (7.1±1.3±3.1)*10-5 Babar (4.9±1.0±0.5)*10-5

  29. X(3940)→DD* and X(4160)→D*D* Mrec(J/ψD) DD*D*π Mrec(J/ψD*) DD* ee→J/ψDD* X(3940) 6.0σ ee→J/ψD*D* X(4160) 5.5σ M=4156 ± 15 MeV =139 ± 21 MeV +25 –20 M =3942 ± 6 MeV =37 ± 12 MeV +7 –6 M(D*D) M(D*D*) +111 – 61 +26 –15 PRL100, 202001 (2008) • Reconstruct J/ψ and one D(*),associatedD(*) seen as peak inMrecoil(J/ψD(*)) • Possible assignments: ηc(3S) ηc(4S) (but X masses ~100-150MeV above predictions for ηc’s) CX=+1 so X(4160)≠ψ(4160)

  30. Y→J/ψππ via ISR Y(4260) Y(4008) PRL 99, 182004 (2007) • Study of e+e-→J/ψπ+π- γISR(548 fb-1) • J/ψ→ee, μμ + ππ; no extra tracks • ISR photon is not detected • Missing mass used to identify process • Y(4260) confirmed • Y(4008) resonance? Re-scattering from DD*? Coupled-channel effect?

  31. Y→ψ’ππ via ISR PRL 99, 142002 (2007) • Study of e+e-→ψ’π+π- γISR(673 fb-1) • ψ’→J/ψππ, J/ψ→ee, μμ + ππ • no additional tracks allowed • γISR not detected • Two significant peaks in M(ψ’ππ): one close to Babar’s Y(4360) but narrower • M(ψ’ππ)fitted with two coherent Breit-Wigners Y(4360) Y(4660)

  32. x-sections for e+e-→ψππ J/ψπ+π- ψ’π+π- • ISR allows us to measure hadronic x-sections in wide energy range: model independent measurement • M(ψππ): background subtracted, corrected for efficiency and luminosity → Cross-section for e+e-→ψπ+π-

  33. B0 →X(3872)K+π– BELLE-CONF-0849 5σ first observation X(3872) sideband X(3872)→J/ψπ+π– non-resonant Kπ K*0→Kπ Mass(Kπ) Br(B0→X(K+π–)non_res) Br(X→J/ψπ+π–) = (8.1±2.0+1.1–1.4)10–6 dominates ! unlike B→K”cc” Br(B0→XK*0)Br(X→J/ψπ+π–) < 3.4x10–6 90% CL ─ Br(B0→X(K+π–)non res) Br(B0→XK0s) ~1 ICHEP2008 Galina Pakhlova, ITEP

  34. B→J/γK & B→(2S)γK evidence NEW B0→XK0s 3.5σ B±→XK± confirmation X(3872)→(2S)γ 3.6σ B0→XK0s B0→XK*0 B±→XK*± B±→XK± X(3872)→J/γ B0→XK*0 B±→XK*± Relatively large Br(X→(2S)γ) is inconsistent with a pure D0D*0 molecular interpretation for X(3872) Favors cc - D0D*0 mixing models ─ ─ ─ K = K, K0s, K*(892) 424fb–1 Br(B±→XK±)Br(X→J/γ) = (2.8±0.8±0.2)10–6 Br(B±→XK±)Br(X→(2S)γ) = (9.9±2.9±0.6)10–6 Br(X→(2S)γ) / Br(X→J/γ) = 3.5 ± 1.4 Br(X→(2S)γ) / Br(X→J/π+π–) = 1.1 ± 0.4 HQ session: Arafat G.Mokhtar ICHEP2008 Galina Pakhlova, ITEP

  35. X(2175) strange analog of Y(4260)? • X(2175)→φ f0(980), φη(confirmed by BESII and Belle) PRD74, 091103 (2006) hep-ex/0808.0006

  36. Hadronic x-sections • From CLEO: scan at 3.97-4.26GeV in 12 points • Total hadronic x-section above DD from BES • Belle: sum of all measured exclusive contributions (3770) (4160) Y(4008) Y(4350) (4415) Y(4260) Y(4660) (4040) Durham Data Base

  37. Is X(3872) a cc state ?

  38. Yb counterpart ? J. Brodzicka @ PIC08 Process Yield σ(pb) BF(%) Г(MeV) “Y(5S)”→Y(1S)ππ 325±20 1.6±0.1±0.1 0.53±0.03±0.05 0.59±0.04±0.09 “Y(5S)”→Y(2S)ππ 186±15 2.3±0.2±0.3 0.78±0.06±0.11 0.85±0.07±0.16 “Y(5S)”→Y(3S)ππ 10±4 1.4±0.5±0.2 0.48±0.18±0.07 0.52±0.20±0.10 • M(ππ) and cosθhel studied Brown-Cahn (CLEO) model (grey) generic phase space (open)

  39. How to identify B meson signal ΔE Mbc ΔE Mbc • Advantage of e+e-→(4S) → BBkinematics: m(4S)~mB+mB no accompanying particles → EB=Ebeam=√s/2in cms • kinematical variables used in B-Factories Mbc= √E2beam- p2B beam-constrained mass (signal at mB~5.28GeV) ΔE=EB- Ebeam cms energy difference (signal peaks at 0) • Resolution improvement (Ebeam is precisely known) • Background separation Example: B0→J/ψ KS

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