Charm Physics at Belle X,Y,Z states: just charmonia or exotics? Jolanta Brodzicka (Krakow) for the Belle Collaboration EXA2011, Vienna, September 2011

Belle @ KEKB-Factory KEK-B: e+(3.5GeV)  e-(8.0GeV), √s=m(4S)~10.58GeV on-resonance e+e-(4S)BB σ~1.1nb (~109 BB) continuum e+e-cc σ~1.3nb (~1.3109 XcYc)  Also a charm factory Data taking: June 1999 - June 2010 Belle II @ SuperKEKB will start in 2014

Charm topics D0-D0 mixing: governed by In SM very suppressed: |x|,|y|~1% (with long distance effects) Mixing modifies decay time: D0→K+π-, K+K-, π+π- lifetime measured, D0→K0sπ+π- time-dependent Dalitz plot analysis,… WA: x=(0.63±0.20)% y=(0.80±0.13)%, still no single-measurement observation CP Violation: In SM ≤0.1%, larger effects would mean New Physics ACP measured for: D0→K+K-, π+π-, Ksη(‘), Ksπ0 D(s)+→Ksπ+, KsK+, φπ+, η(‘)π+ So far no evidence of CPV, but sensitivity ~0.2% at most Decays: weak decays (like above), (semi-)leptonic D0→πlν, Klν, Ds+→μν for form factors and decay constants, radiative D10→D0γ for quark model tests, rare D0→l+l- for New Physics Production of charmonia Spectroscopy and strong decays of mesons, baryons and cc(-like) states hadron charm physics

Charmonia n(2S+1)LJ hc c Many empty slots to fill 2 M(D) recently measured Quantum numbers (4160) (4415) (4040) (3770) χc2′ ′ ηc′ ηc J/ χc2 χc0 hc χc1 n(2S+1)LJ Many empty slots to fill Expected broad states decaying to DD, DD*, D*D* All cc states predicted below 2mD were observed Good agreement with QCD predictions cc spectrum „cleaner” than uu/dd/ss → cc-like exotics easier to identify

Charmonium production in B-Factory

Particles discovered at Belle: history 2002: ηc’→KsKπ D**: D*0(2308)→Dπ D1’(2420)→D*π D*s0(2317)→Dsπ0 Ds1(2460)→Ds*π0 X(3872) →J/ψπ+π- Y(3940)→J/ψω Σc(2800) →Λc+π X(3940)→D*D χc2’→DD Ξc(2980), Ξc(3077)→ΛcKπ DsJ(2700) →D0K Y family→J/ψπ+π- , ψ(2S)π+π- X(4260)→D*D* Z±(4430)→ψ(2S)π± Z±(4051), Z±(4250)→χc1π± 2011: hb(1P),hb(2P) in Y(5S) →hbπ+π- Zb±(10610), Zb±(10650)→Y(nS)π±, hbπ± Will focus on charmonium-like XYZ Are they exotic? D*s0(2317) Ds1(2460) Y(3940) Σc(2800)0 Ξc(2980) Ξc(3077) DsJ(2700) χc2’

XYZ charmonium-like states Name JPC Γ (MeV) Decay modes Production Exp’s X(3872) 1++ 2-+ <1.2 π+π-J/ ψ; γJ/ψ; D0D*0 B→KX, pp→X+any Belle/CDF/D0 BaBar/LHCb X(3940) 0?+ 37 DD* (not DD, ωJ/ψ) e+e-→J/ψX Belle Y(3940) 0,2++ 30 ωJ/ψ (not DD*) B→KY, γγ→Y Belle/BaBar Y(4140) ??? 15 φJ/ψ B→KY CDF (not Belle) X(4160) ~140 D*D* (not DD, DD*) Y(4008) 1-- ~220 π+π-J/ψ e+e-→YγISR Belle (not Babar) Y(4260) ~80 π+π-J/ψ (not π+π-ψ’) BaBar/CLEO/Belle Y(4360) ~75 π+π-ψ’ (not π+π-J/ψ) BaBar/Belle Y(4660) ~50 π+π-ψ’;ΛcΛc (?) Z±(4430) ??? ~100 ψ(2S)π± B→KZ Belle (not Babar) Z±(4050) ~80 χc1π± Belle Z±(4250) ~180

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 q c π D D(*) q c c g π c

X(3872), the most famous PRL91, 262001(2003) Most cited Belle paper X(3872)→J/ψπ+π- observed in B→X(3872)K by 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)? 711/fb N~170 arXiv:1107.0163 M(J/ψπ+π-) PRL103, 152001(2009) 2.4/fb N~6000 657M BB D*→Dγ D*→D0π0 M(D0D*0) PRD81, 031103 (2010)

JPC of X(3872) M(π+π-)~ρ(770) in X(3872)→J/ψππ arXiv:1107.0163 M(π+π-) __ S-wave .... P-wave 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 PRL107, 091803 (2011) B+→XK+ 711/fb M(J/ψγ) M(ψ’γ) JPC=1++ JPC= 2-+ PRL102, 132001 (2009)

Properties of X(3872) Belle evidence of X(3872)→J/ψπ+π-π0, confirmed by Babar  Large isospin violation. Unlikely for usual cc No evidence of charged partner X(3872)±→ J/ψπ±π0 arXiv:0505037 B± B0 M(J/ψω) 426/fb BaBar: PRD71,031501(2007) Belle: arXiv:1107.0163 M(J/ψπ+π0)

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 arXiv:0407033

Y(3940)→J/ψω Y(3940)→J/ψω in B→ KY Y(3940)→J/ψω in γγ fusion M(J/ψω) X(3872) Y(3940) 426/fb PRD82, 011101 (2010) Y(3940) 253/fb PRL 94, 182002 (2005) M(J/ψω) Γ(Y→J/ψω)>1MeV Too large for cc D*D* molecule rescattering to J/ψω? e+e- undetected pt balance required for final state Partial wave analysis: JP=0+,2+ prefered 694/fb PRL104, 092001 (2010) M(J/ψω) eff vs W: drop at 3.9GeV. included in fit S-wave BW + 2G

1-- Y family from ISR e+e-→J/ψπ+π-γISR and ψ(2S)π+π-γISR studied ISR photon not required. ISR process identified with missing mass and angular distribution Study inv. mass of the final state hadrons Y(4008), Y(4260), Y(4360), Y(4660) found Not all of them can be usual charmonia, only one empty 1-- slot left s=E2CM-2ECMEISR continuous ISR spectrum  energy ‘scanning’ Produced states carry JPC of photon PRL99, 182004 (2007) PRL 99, 142002 (2007) 550 fb-1 Y(4008) 7σ Y(4260) Y(4360) Y(4660) 6 670 fb-1 M(J/ψπ+π-) M(ψ’π+π-) ~80pb in Y(4260) and Y(4360) peaks

Y family, properties Study of e+e-→J/ψπ0π0 γISR (ISR photon required) Motivation: study isospin relation i.e. Y(4260)→J/ψπ0π0 wrt. Y(4260)→J/ψπ+π- Large isospin violation would be exotic signature Observed very little Y(4260) signal Consistent with isospin expectation ψ’ Y(4260) M(J/ψπ0π0) M(J/ψπ0π0) ψ’ S~630 Y(4260) Preliminary 820/fb ~80pb in Y(4260) and Y(4360) peaks

1-- Y→open charm? ? e+e-→open charm γISR D*D* DD* (4040) (4160) Y(4008) (4415) Y(4660) Y(4260) Y(4350) DD DDπ Λc+Λc– ? PRD77,011103(2008) PRL100,062001(2008) PRL98, 092001 (2007) PRL101, 172001(2008) Y(4008), Y(4260), Y(4360), Y(4660) are above open charm threshold but don’t match peaks in D(*)D(*) cross-sections 90%CL limits for Y(4260): Widths for Y→ψππ transition too large for conventional charmonia Y(4260) is DD1 molecule, ccg hybrid? Then Y(4260)→DD*π should dominate But no signal found PRD79,092001(2009) PRD80,091101(2009) DD*π Y(4260) ψ(4415) Y(4660) ?

Charged cc-like states: must be exotic! Conventional Molecule Tetraquark Hybrid Hadrocharmonium Z+(4430)→ψ’π+ Z+(4050) , Z+(4250)→χc1π+ Any Z+→J/ψπ+? Study ongoing M2(ψ’π+) q c π D D(*) q c M(χc1π+) c g π c

Z(4430)±→ψ’π± was the first PRL100, 142001 (2008) PRD80, 031104 (2009) Method: Dalitz-plot analysis of B→ψ’π+K B→ψ’π+K amplitude: coherent sum of Breit-Wigner contributions Models: all known K*→Kπ+ resonances only all known K*→Kπ+ resonances and Z+→ψ’π+  favored by data (significance: 6.4σ) [cucd] tetraquark? neutral partner in ψ’π0 expected D*D1(2420) molecule? should decay to D*D*π M2(Kπ+) M2(ψ’π+) Z+(4430) K2*(1430) K*(890) M2(ψ’π+) with K*’s vetoed 605/fb –̶̶̶̶̶̶ –̶̶̶̶̶̶ Dalitz fit for model with K*’s only –̶̶̶̶̶̶ –̶̶̶̶̶̶ Dalitz fit for model with K*’s and Z

Z(4430)±→ψ’π± in BaBar data? Fits to efficiency corrected M(ψ’π+): no significant Z+(4430) signal M(ψ’π+) from BaBar is statistically consistent with Belle data (χ2/ndf=54.7/58) CDF result expected soon Belle peak position PRD79, 112001 (2009) M2(ψ’π+)

Any pattern in the XYZ puzzle? Lots of non-cc candidates @ 4GeV Charged Z states must be exotic, neutral XY may be exotic They have large hadronic transitions: unusal for conventional charmonia No good candidates in cc spectrum or/and not enough empty slots Close to the thresholds: what about threshold effects? Mass ~ M(D+D*), M(Ds*+Ds*): molecules? New spectroscopy @4GeV No single model can accomodate all XYZ states Waiting for related predictions from Lattice QCD Waiting for new mesurements and new data „The finder of a new elementary particle used to be rewarded by a Nobel Prize, but such a discovery now ought to be punished by a 10,000 dollar fine.” Willis Lamb, Nobel Prize Lecture, 1955

Backup

cc (-like) state of art We have added a few new states… Are they conventional cc? Do we understand them? ηc(4S) Y(3360), Y(3660)

Angular analysis of X(3872) at Belle

X(3872) backups M((2S)γ) M(J/γ) 0++ 1++ 1-- 2-+ 0.78/fb 3.6σ 424/fb PRL98, 132002 (2007) 0.78/fb 3.6σ 424/fb 3.5σ M((2S)γ) M(J/γ)

Belle-BABAR comparison Uncorrected data in the K* veto region BABAR preliminary Both Belle and BABAR data are re-binned (to calculate χ2) and side-band subtracted The BABAR data are normalized (*1.18) to the Belle sample; Luminosity ratio is 1.46 The data distributions are statistically consistent (χ2=54.7/58)

for 1<M2(K-π+)<1.75GeV2 Two Z±→χc1π± Dalitz-plot analysis of B0→χc1π+K- χc1 →J/ψγ with 657M BB Dalitz plot models: known K*→Kπ only K*’s + one Z →χc1π± K*’s + two Z± states  favored by data Significance: 5.7σ PRD 78, 072004 (2008) M2(χc1π+) M2(K-π+ ) K2*(1430) K*(1680) K*(892) K0*(1430) K3*(1780) ??? –̶̶̶̶̶̶ –̶̶̶̶̶̶ fit for model with K*’s –̶̶̶̶̶̶ –̶̶̶̶̶̶ fit for double Z model –̶̶̶̶̶̶ –̶̶̶̶̶̶ Z1 contribution –̶̶̶̶̶̶ –̶̶̶̶̶̶ Z2 contribution M(χc1π+) for 1<M2(K-π+)<1.75GeV2

Zb±→Y(1,2,3S)ππ