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Charmonium results at Belle

Charmonium results at Belle. Jolanta Brodzicka (Krakow) for the Belle Collaboration DIS2012 , HF session Bonn , 26-30 March 2012. c.  (4415). c.  (4160).  (4040). χ c2 ′. DD*.  (3770). DD. ′. η c ′. χ c2. χ c1. h c. χ c0. J/ . η c. Charmonia: state of art.

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Charmonium results at Belle

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  1. Charmonium results at Belle Jolanta Brodzicka (Krakow) for the Belle Collaboration DIS2012, HF session Bonn, 26-30 March2012 J.Brodzicka Charmonia@Belle DIS2012

  2. c (4415) c (4160) (4040) χc2′ DD* (3770) DD ′ ηc′ χc2 χc1 hc χc0 J/ ηc Charmonia: state of art n(2S+1)LJ • Expected broad states decaying to DD, DD*, D*D* Exception: some of the 1D-multipletstates • All cc states predicted below 2mD were observed • Good agreement with QCD predictions To do: • Fillmany empty slots above DD-threshold • Accomodate cc-like XYZ states. If possible... Godfrey-Isgur, PRD 32, 189 (1985) J.Brodzicka Charmonia@Belle DIS2012

  3. To find (out) more Strategy: • Precision measurements of already observed states today: updates on X(3872)→J/ψπ+π-PRD84, 052004 (2011) • Study new final states today: Χc1γ, J/ψηPreliminary Goal: • to find missing charmonia • to understand nature of XYZ • to find more... J.Brodzicka Charmonia@Belle DIS2012

  4. Charmonia at Belle • Belle @ KEKB-Factory e+e-(nS) n=1,..5. Mostly (4S) • cccontinuum under ’s and b→c processes  charm factory • Charmonium(-like) states from Belle: ηc’, χc2’, X(3872), Y(3940), Y(4360), Y(4660), Z+(4430), Z+(4050), Z+(4250) J.Brodzicka Charmonia@Belle DIS2012

  5. 0±+, 2±+... Charmonium production in B-Factory J.Brodzicka Charmonia@Belle DIS2012

  6. Charmonia from B decays : method • Use e+e-→Y(4S) data • Reconstruct decay chain, for example: B+→J/ψπ+π-K+, B+→J/ψγK+ (J/ψ→e+e-,μ+μ-) • Identify B signal with ΔE and Mbc exploit kinematics of Y(4S)→BB EB=Ebeam=√s/2 (known precisely) • Improve resolution: fit J/ψ vertex, constrain M(l+l-)→mJ/ψ, ΔE→0 (rescale Eγ) • Study M(J/ψπ+π-) or M(other final state) • Identify/parameterize background with inclusive B → J/ψX MC • Use control sample for callibration/validation: ψ’→J/ψπ+π-, χc1→J/ψγ, ... Example: B+→J/ψγK+signal MC region of B signal X(3872)→J/ψγ ΔE = 0 for signal. Tail due to radiative losses J.Brodzicka Charmonia@Belle DIS2012

  7. Updates on X(3872)→J/ψπ+π- PRD84, 052004 (2011) J.Brodzicka Charmonia@Belle DIS2012

  8. X(3872), M and Γ updates Observation of X(3872) PRL91, 262001 (2003) Most cited Belle paper ~630 citations • B→J/ψπ+π-K K=K+,Ks with full Belle data of 772 ×106 BB • 3D unbinned ML fit to Mbc -M(J/ψπ+π-)-ΔE • X(3872) mass resolution (scaled) from ψ’ data. MX bias: 0.92±0.06MeV • σM~4MeV, but 3D fit allows sensitivity to ΓX. UL from scan of likelihood profile Signal PDF: BW+2G Γ< 0.95 MeV@90%CL + 0.23 MeV bias from measured Γ(ψ’) B+→XK+ N=151±15 Belle: MX(3872) = 3871.84±0.27± 0.19 MeV ΓX(3872)<1.2MeV @90%CL PDG: MX(3872)→J/ψππ = 3871.67±0.17 MeV M(D0)+M(D*0)=3871.8 ±0.3 MeV ΓX(3872)<2.3MeV @90%CL Mass difference of X from B+ and B0: ΔMX = -0.69±0.97 ± 0.19 MeV B0→XKs N=21±6 (6.1σ) ΔM=8±3 MeV in diquark-antidiquark model PRD71, 014028 (2005) Mbc M(J/ψπ+π-) ΔE J.Brodzicka Charmonia@Belle DIS2012 ■ x-feed from B→J/ψK1(1270),J/ψK*2(1430)

  9. Angular analysis of X(3872) • JPC=1++ or 2-+ from angular analysis by CDF PRL98, 132002 (2007) • For X(3872)→J/ψρ→J/ψπ+π- with J/ψ-ρ orbital momentum L and spin S: JPC=1++: L=0 S=1  1 amplitude JPC=2-+: L=1 S=1 or 2  2 amplitudes B11, B12 • Angles in X(3872) cms system by Rosner PRD70, 0942003(2004) • 1D projections compared with MC predictions • Both JPC=1++ and 2-+(for certain B11/B12) describe data well • More data needed to distinguish θX is X helicity angle 1++ 2-+B11/B12=1.5*exp(60°i) χ2=3.8 Χ2=1.8 Χ2=0.6 χ2=4.7 Χ2=4.6 Χ2=5.2 |cosθX| |cosθX| |cosχ| |cosχ| |cosθl| |cosθl| ___ MC expectations ...... Background from sidebands J.Brodzicka Charmonia@Belle DIS2012

  10. Background subtracted and corrected for relative acceptance X(3872)→J/ψππ, updates ρ→π+π- with ρ-ω interference ___ L=0 χ2/ndf=16/17 ......L=1 χ2/ndf=15/17 • M(π+π-) shape important for P-parity X(3872)→J/ψρ in relative S-wave: P=+, P-wave: P=- • High-mass part of M(π+π-) sensitive to L through centrifugal barier • Both orbital momenta acceptable with included interference of X(3872)→J/ψρ and J/ψω final states • Search for charged partner X(3872)+→J/ψπ+π0 crucial for 4-quark models • 2D ML fit to Mbc-M(J/ψπ+π0) • MX limited to 10MeV windows in 3.85-3.89GeV • Largest yield: N=4±8 for MX=3873±6 MeV • X+ is ruled out or is (much) broader? • C-parity=+ from observed X(3872)→J/ψγ X(3872) partner with C-parity=- exists? Study J/ψη and χc1γ final states Signal PDF: CB fixed Mbc M(J/ψπ+π0) J.Brodzicka Charmonia@Belle DIS2012

  11. Study of χc1γ Preliminary J.Brodzicka Charmonia@Belle DIS2012

  12. Study of χc1γ, introduction X(3872)→χc1γ • Belle for 152M BB, focused on X(3872) PRL91,262001 (2003) • Can (narrow) charmonia contribute? • Missing 1D-multiplet, mostly narrow ψ2 does not decay to open-charm (DD violates parity, DD* too heavy) Γ~300-400keV • Γ(ψ2→χc1γ)=260keV predicted ψ3 has no E1 transition to χc1γ, ηc2→χc1γ forbidden due to parity Godfrey-Isgur, PRD 32, 189 (1985) Eichten-Lane-Quigg, PRL 89, 162002 (2002); PRD 69, 094019 (2004) M(χc1γ) J.Brodzicka Charmonia@Belle DIS2012

  13. N/18MeV M(χc1γ) Study of χc1γ • B+→χc1γK+ with χc1→J/ψγ using 772 ×106 BB • photons from π0vetoed • χc1’s γ veto: γ giving best χc1 candidate not used as B daughter • best B candidate with ΔE closest to 0;optimized signal window: -28<ΔE<30 MeV • γ from B: scaled to ΔE=0  M(χc1γ) resolution 7→5MeV for ψ’→χc1γ • Efficiency and resolution improve with increasing M(χc1γ) (Eγincreases) • M(χc1γ) in data agree with inclusive MC, except for peak at 3.82GeV • Missing ψ2 (13D2) charmonium? Mass agrees with predicted • data for Mbc>5.27GeV ■ signal B→ψ’K+, ψ’→ χc1γ from MC ■ peaking bckgd from MC: B→ψ’K+,ψ’ →J/ψπ0, J/ψη, J/ψππ ■ combinatorial bckgd from MC: B→J/ψK*, χc1K*, ψKπ(π), χc1Kππ ψ2? J.Brodzicka Charmonia@Belle DIS2012

  14. ψ→χc1γ, 2D ML fit to M(χc1γ)-Mbc N/7.5MeV N/1.24MeV • Mbc signal PDF: the same for ψ’ and ψ2 • ψ’ mass signal: 2G (free σcore, σtail=19MeV fixed from MC) • Ψ2 mass signal: Γ=0, σcore from MC (~4MeV) scaled with ψ’σdata/σMC ~1.3 • Background shapes fixed from fit to inclusive MC • ψ2 significance 4.2σw/syst. First evidence! • Γ(ψ2)= 4±6 MeV if fitted, poor sensitivity • Resultfor ψ’ consistent with PDG • Fit validated with Toy MC Mbc for ψ’ region 3.66<M(χc1γ)<3.71GeV Backgrounds: ■B→ψ’K+, ψ’→non-χc1γ ■B→ψK*, χc1K*, ψKπ, χc1Kπ ■ combinatorial Signals: ■B→ψ’K+, ψ’→χc1γ ■B→ψ2K+, ψ2→χc1γ Mbc for ψ2 region 3.805<M(χc1γ)<3.845GeV M(χc1γ) Mbc J.Brodzicka Charmonia@Belle DIS2012

  15. X(3872)→χc1γ N/5MeV N/1.24MeV • Decay allowed for X(3872) partner with C=- • X(3872) resolution model like for ψ2 • No X(3872) signal observed: S=-1±5 • using recent Belle measurement PRD84, 052004 (2011) • Improved constraint ψ2 X(3872) Mbc for X(3872) region 3.84<M(χc1γ)<3.90GeV M(χc1γ) Mbc J.Brodzicka Charmonia@Belle DIS2012

  16. Study of J/ψη Preliminary J.Brodzicka Charmonia@Belle DIS2012

  17. ψ’ X(3872) Study of J/ψη • Babar with 90×106 BB, no X(3872) signal PRL93, 041801(2004) • Belle: B+→J/ψηK+η→γγ using 772×106 BB • Eγ>100MeV, energy balance |E1-E2|/(E1+E2)<0.8 • photons from π0vetoed, η mass constrained • Best B candidate: with best J/ψ and η masses • B+→ψ’K+ with ψ’→J/ψππveto to suppress bckgd. • 1st: Measure total B+→J/ψηK+: study ΔE for Mbc>5.27GeV • 2nd: Study M(J/ψη) for -35<ΔE<30 MeV optimized signal window • data for Mbc>5.27GeV ■B→J/ψηK+ signal (2G, free) ■ B→ψ’K+,ψ’ →non-J/ψη bckg.from MC ■ B→χc1K+from MC ■ combinatorial M(J/ψη) B+→J/ψηK+ S=428±37 J.Brodzicka Charmonia@Belle DIS2012

  18. ψ’ ψ’ region X(3872) M(J/ψη) • J/ψη in data: only signal from ψ’ and non-resonant component, no X(3872) • 1D fit to M(J/ψη) • ψ’ signal: 2G, fixed to MC (σcore~2MeV) • Background fixed from fit to inclusive MC • data for Mbc>5.27GeV, -35<ΔE<30MeV ■B→ψ’K+, ψ’ →J/ψηsignal ■B→J/ψηK 3-body signal ■ MC bckgd: B→ψ’K+,ψ’ →non-J/ψη + combinatorial ψ‘→J/ψη S=52 ± 8 Non-resonant J/ψη S=395 ± 26 X(3872) S=2±5 M(J/ψη) J.Brodzicka Charmonia@Belle DIS2012

  19. Summary • Belle continues studying cc(-like) states to test their (exotic) nature • Update on X(3872) properties Best limit on width, ΓX(3872)<1.2MeV @90%CL Angular analysis, M(π+π-)study: both JPC=1++ and 2-+ still possible X(3872)→ηcπ+π-,J/ψω may help No charged partner of X(3872) • Study of the of χc1γ First evidence of a new state at 3823 MeV Missing ψ2 (13D2) charmonium? ψ2→J/ψπ+π-,χc2γ may answer • Study of the J/ψη Apart from ψ’, no narrow state contributes (90%C.L UL of O(10-6)) • No contribution from C-odd X(3872) partner in neither χc1γ or J/ψη J.Brodzicka Charmonia@Belle DIS2012

  20. Backups J.Brodzicka Charmonia@Belle DIS2012

  21. Systematic J.Brodzicka Charmonia@Belle DIS2012

  22. Backups J.Brodzicka Charmonia@Belle DIS2012

  23. M(J/ψππ) resolution and bias • MC • ψ’ data J.Brodzicka Charmonia@Belle DIS2012

  24. B→ψ’K control sample J.Brodzicka Charmonia@Belle DIS2012

  25. X(3872)→J/ψππ • Width bias from MC • X(3872) mass systematic, BF products in data J.Brodzicka Charmonia@Belle DIS2012

  26. Theory: NR model (left), Isgur-Wise relativized model (right), dashed: spin triplets, dotted: spin singlets J.Brodzicka Charmonia@Belle DIS2012

  27. Established charmonia, quark model multiplets, spectroscopic assignment J.Brodzicka Charmonia@Belle DIS2012

  28. XYZ charmonium-like states J.Brodzicka Charmonia@Belle DIS2012

  29. c c π c q q c c q D D(*) q c c π π c c g c Conventional and exotics particles • Quark Model by Gell-Mann and Zweig (1964): (qq) mesons and (qqq) baryons = conventional states • States more complex =exotics also predicted by potential models based on QCD Phenomenology menu of cc-like exotics: • Molecule: Meson-antimeson loosely bound by pion exchange Mass: ≈ sum of meson masses Decay: dissociation into constituent mesons • Tetraquark: „Coloured” quarks tightly bound by gluon exchange Decay:rearrange into „white” mesons → dissociation Can have non-zero charge [cucd] and/or strangeness [cucs] • Hybrid: cc+ constituent excited gluons Can bear exotic JPC: 0+-, 1-+, 2+-… Lowest cc-hybrids predicted by LQCD @4.2GeV Large partial widths for hadronic transitions (i.e. to ψππ, ψω…) • Hadrocharmonium: charmonium coated by excited light hadron matter J.Brodzicka Charmonia@Belle DIS2012

  30. PRL103, 152001(2009) arXiv:1107.0163 711/fb N~170 2.4/fb N~6000 D*→Dγ M(J/ψπ+π-) D*→D0π0 657M BB M(D0D*0) X(3872), the most famous PRL91, 262001(2003) Most cited Belle paper • X(3872)→J/ψπ+π- observed in B→X(3872)Kby Belle in 2003 • Confirmed by Babar, CDF, DØ, LHCb, CMS • Mass below or above D0D0*? (bound/virtual state?) • Peak at D0D*0 threshold is from X(3872)? PRD81, 031103 (2010) J.Brodzicka Charmonia@Belle DIS2012

  31. arXiv:1107.0163 __ S-wave .... P-wave PRL107, 091803 (2011) M(π+π-) B+→XK+ 711/fb JPC=1++ JPC= 2-+ M(J/ψγ) M(ψ’γ) JPC of X(3872) • M(π+π-)~ρ(770) in X(3872)→J/ψππ  X(3872)→J/ψρ in S or P-wave  P-parity=+/- • Radiative X(3827)→J/ψγ decays  C-parity=+ But from Babar: • Angular analysis (Belle, CDF) JPC=1++ or 2-+ difficult to discriminate further PRL102, 132001 (2009) J.Brodzicka Charmonia@Belle DIS2012

  32. What is X(3872)? • charmonium? no good candidate ηc2 (2-+) mass OK, JPC=2-+ supported by Babar’s X(3872)→J/ψω X(3872)→ ηcππ should dominate If X(3872) is cc, then why so narrow? • tetraquark? no evidence of Xu=[cu][cu] Xd=[cd][cd] neutral doublet nor charged partner X±→J/ψπ±π0 • DD* molecule? supported by large width of X(3872)→D0D*0 Large BR(X→ψ(2S)γ) from Babar is problematic. Mixture of cc and DD* molecule? Rulling out charmonia candidates... ηc(3S) X(3872) too light and narrow hc(2P) ruled out by angular analysis χc1(2P) BR(X→J/ψγ) too small ηc2(1D) BR(X→J/ψππ) too large ψ2(1D) BR(X→χc1γ) too small ψ3(1D) BR(X→χc2γ) too small J.Brodzicka Charmonia@Belle DIS2012 arXiv:0407033

  33. 424/fb 3.6σ 3.5σ 0++ 1++ 1-- 2-+ M(J/γ) M((2S)γ) PRL98, 132002 (2007) 0.78/fb X(3872) backups J.Brodzicka Charmonia@Belle DIS2012

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