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X Y (but not Z) states, experimental overview

This document provides an overview of the experimental measurements and observations of X and Y mesons in the .XY. states, focusing on decay to final states with a cc pair and Sqi=0. It covers topics such as the decay of X(3872) to Kp+p-J/y, Y(4260) and y' states, and the new measurements from Belle and BaBar experiments. The document also discusses the controversies and different cc assignments for the X(3915), X(3940), and X(4160) states.

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X Y (but not Z) states, experimental overview

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  1. XY (but not Z) states, experimental overview Stephen L. Olsen University of Hawai’i (member: BES & Belle expts)

  2. (Decay to final states with a cc pair & Sqi=0 ) X & Y mesons X(3872) BKp+p-J/y Y(4260) y’ Belle BaBar e+e-gISRp+p-J/y Belle X(3872) Y(4008)? M(p+p-J/y)-M(J/y) Belle Y(3940) BaBar M(p+p-J/y) BKwJ/y Y(4350) & Y(4660) e+e-gISRp+p-y’ BaBar Belle M(wJ/y) M(wJ/y) M(p+p-y’) X(4160) X(3940) Y(4140) Y(4630) e+e-DD*J/y e+e-D*D*J/y e+e-gISRLcLc Belle CDF Belle Belle BKfJ/y M(LcLc) M(DD*) M(D*D*) M(fJ/y)

  3. Neutral cc X & Y mesons

  4. What’s new? • Belle sees a ggwJ/y peak @ ~3915 MeV • New to this meeting • Belle measurements of s(e+e- D*Dp) • New to this meeting (G. Pakhlova’s Thurs talk) • CDF evidence for Y(4140)fJ/y • Moriond QCD Kay Yi’s talk this session • Z(4430)+p+y’; Z1(4050)+ & Z2(4250)+p+cc1 • controversy? Chistov & Patrigani in the next session • BaBar results for X(3872)gJ/y & gy’ • Mass measurements from CDF & Belle

  5. The states near 3940 MeV-circa 2005- probably different not seen in wJ/y not seen in DD* Probably the cc2’ X(3940) Y(3940) Z(3930) gg DD e+e- J/y DD* BKwJ/y M(wJ/y) M(DD) M(DD*) M = 3929±5±2 MeV Gtot = 29±10±2 MeV Nsig =64 ± 18evts M≈3940 ± 11 MeV G≈ 92 ± 24 MeV M = 3942 +7± 6 MeV Gtot = 37 +26 ±12 MeV Nsig =52 +24 ± 11evts -6 -15 -16 PRL 96, 082003 PRL94, 182002 (2005) PRL 100, 202001

  6. Y(3940) confirmed by BaBar B±K±wJ/y B0KSwJ/y ratio M(wJ/y) PRL 101, 082001 Some discrepancy in M & G; general features agree

  7. New Belle peak in ggwJ/y undetected l+ X J/y l- p+ w p0 p- undetected

  8. M(p+p-p0)vs M(l+l-) J/yl+l- • 4 trks (1 lepton, no kaons) • Sqi=0 • 1 p0  select best one • veto y’p+p-J/y • W<4.3 GeV • SpT<0.1GeV • … wp+p-p0 M(p+p-p0) GeV M(l+l-) GeV

  9. SpTvs W cut M: 3914  3  2MeV, G: 23  10 +2-8 MeV, Nres = 55  14 +2-14 events Signif. = 7.7s, 7.7s preliminary

  10. The 4 states near 3940 Mass(GeV) Range: (s(stat.)+s(sys.)) Y(3940) Belle X(3940) Z(3930) Good overlap with BaBar “Y(3940)” values This X(3915) Width(GeV)

  11. Could it be the Z(3930)? Seems unlikely

  12. Ggg partial width GggB(wJ/y) = 69  16 +7eV (JP=0+) -18 GggB(wJ/y) = 21  4 +2 eV (JP=2+) -5 For comparison: Z(3930): GggB(DD) = 180  50±30 eV Bf(cc2’wJ/y) Bf(cc2’DD) If X(3915) = Z(3930) = cc2’  0.08 Huge for above-open-charm-threshold charmonium

  13. cc assignments forX(3915), X(3940) & X(4160)? hc’’’ 4160MeV hc” cc0’ 3940MeV 3915MeV • Y(3915) = cco’? G(wJ/y) too large? • X(3940) = hc”?  mass too low? • X(4160) = hc’’’?  mass way too low?

  14. + J/ - primary vertex secondary vertex Lxy +  - B+ + Particle Identification (Kaon LLR) Vertex separation Y(4140) from CDF arXiv:0903.2229 Kai Yi’s talk in This session M: 4143.0  2.9  1.2MeV, G: 11.7 +8.3-5± 3.7MeV, Nres = 14  5events Signif. > 3.8s M=m(+-K+K-)-m(+-)

  15. comment on JPC of the X(3872)

  16. Fit toM(pp)favorsL = 0  hep-ex/0505038 PRL96,102002(2006) JPC values from CDF & Belle JPC = 1++ CDF: PRL 98 132002 JPC = 1++ or 2-+

  17. BaBar: X(3872) gJ/y & gy’ B+K+gJ/y 3.6s 1++ g J/y or gy’  Allowed E1 2-+  gJ/y or gy’  Suppressed E2 M(gJ/y) JPC = 1++ favored over 2-+ B+K+gy’ 3.5s NB: Molecular models have trouble with X(3872)gy’ Swanson PLB 598, 192 (2004) PRL 102,132001 M(gy’)

  18. Is there a cc assignment for X(3872) ? cc1’ hc2 ?? ?? 3872MeV • Mass is too low • especially if cc0=3915 & cc2=3930 • cc1’ppJ/y violates Ispin • Bf(X3872ppJ/y)>4% • G(gJ/y) should be >>G(rJ/y) • expt: G(gJ/y) <<G(rJ/y) • Mass is okay • hc2ppJ/y violates Ispin • Should be ,, hc2 pphc • G(gJ/y) should be tiny • BKhc2 is suppressed

  19. the 1-- Y states Y(4260) Y(4350) & Y(4660) BaBar e+e-gISRp+p-J/y e+e-gISRp+p-y’ BaBar Belle Belle Y(4008)? M(p+p-J/y) GeV M(p+p-y’) GeV e+e-gISRLcLc at least 3, maybe 5 Y(4630) Belle M(LcLc)

  20. Only 1 unassigned 1-- cc level predicted measured

  21. If not charmoniumwhat else?

  22. --many proposals-- • L Maiani et al • PRD 71,014028 (2005) • T-W Chiu & TH Hsieh • PRD 73, 111503 (2006) • D Ebert et al • PLB 634, 214 (2006) • … • NA Tornqvist • PLB 590, 209 (2004) • ES Swanson • PLB 598,197 (2004) • E Braaten & T Kusunoki • PRD 69 074005 (2004) • CY Wong • PRC 69, 055202 (2004) • MB Voloshin • PLB 579, 316 (2004) • F Close & P Page • PLB 578,119 (2004) • X Liu • arXiv 0708..4167 • … • P Lacock et al (UKQCD) • PLB 401, 308 (1997) • SL Zhu • PLB 625, 212 (2005) • FE Close, PR Page • PLB 628, 215 (2005) • E Kou, O Pene • PLB 631, 164 (2005) • … _ cc-gluon hybrid • Etc: • hadro-charmonium • threshold effects • … c c • C Meng & KT Chao • PRD 75, 114002 (2007) • W Dunwoodie & V Ziegler • PRL 100 062006 (2008) • O Zhang, C Meng & HQ Zheng • arXiv:0901.1553 • … • S Dubynski et al • PLB 666,344 (2008) • FK Guo et al • PLB 665, 26 (2008) • DV Bugg • arXiv+0709.1254 • … modified charmonium

  23. Model features diquark-diantiquarks Expect SU(3) multiplets cc-gluon hybrids LQCD: M>~4.3 GeV Open charm thresh =MD+MD**4285 (above Y4260 peak) Non-zero charges are not allowed D(*)D(*) molecules (real or virtual) masses should be near M(D(*))+M(D(*)) mass thresholds • Etc. • hadro-charmonium • light hadron-charmonium • bound states • threshold effects • …

  24. D(*)D(*) Molecules? masses should be near M(D(*))+M(D(*)) mass thresholds Favored model for the X(3872) Lots of literature on this, some very detailed (& some prior to the X(3872) discovery)

  25. X(3872) Mass-- in ppJ/y channel only -- 2 new measurements Belle Avg: MX(3872) = 3871.5±0.2 MeV PDG08: MD0+MD*0 = 3871.8±0.4 MeV CDF T. Kuhr @ QWG08

  26. DD thresholds DSDS thresholds some of the states are near thresholds – notably M(X3872) & M(D0)+M(D*0) - but this is not a universal feature

  27. Hybrids? LQCD: M>~4.3 GeV Open charm thresh =MD+MD** 4285 MeV (above Y4260 peak) Non-zero charges are not allowed Should be seen in open-charm channels above 4285 MeV Favored assignment for the 1-- Y states

  28. DD** thresholds and the Y(4260), Y(4350) & Y(4660) 4.66- 4285 D D 4.35- D Belle D 4.28- 4.26- 3.88- D 3.85- DD Y(4350) & Y(4660) are well above all DD** thresholds & should have strong widths to DD*p

  29. σ(e+e–→open charm) via 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 PRL 101 172001 (2008) Λc+Λc– No evidence for any 1-- YD**D

  30. Belle: Sum of all measured exclusive contributions (3770) (4160) Y(4008) Y(4350) (4415) Y(4260) Y(4660) (4040) Durham Data Base if Ruds=2.285±0.03 Almost all open-charm channels are accounted for Inclusive (BES) New Belle results on DD*p in G. Pakhlova’s Thurs PM talk Sexclusive (Belle)

  31. These states have large G(ppJ/y(y’)) eg:G(Y(4260)p+p- J/y) > 1.6MeV @ 90% CL X.H. Mo et al, PL B640, 182 (2006) Much larger than measured charmonium widths: G(y’p+p- J/y) = 0.104 ±0.004 MeV G(y’’p+p- J/y) = 0.044 ±0.008 MeV

  32. diquark-diantiquarks Expect SU(3) multiplets Isospin partners S=-1 partners Xs-= X-= d s doublet of “X(3872)” states DM=8±3 MeV Maiani et al PRD71, 014028

  33. PRD71, 031501 B0 B- X(3872)– X(3872)– M(J/π–π0) M(J/π–π0) No multiplet partners seen BaBar search for “X-(3872)”p-p0 J/y Bf(B0K+X-)Bf(X-p-p0J/y) < 0.4 Bf(B-K+X0)Bf(X0p+p-J/y) (expect  2)

  34. X(3872)→J/ψπ+π– BELLE-CONF-0849 PRD77,111101,2008 B+→XK+ B+→XK+ 12.8 8.6σ B0→XK0s B0→XK0s 2.3σ 5.9 No evidence for X(3872) neutral partner MX= 2.7±1.6±0.4 MeV MX =0.2±0.9±0.3MeV DM=8±3 MeV predicted Maiani et al PRD71, 014028

  35. Mass different in XDD* modes? “new” “old” 605fb-1 D0D0g 414fb-1 D0D0p0 605fb-1 D0D0p0

  36. Light-hadron charmoniumbound states? c c My guess: masses should be near M(cc)+M(“narrow”-light-hadron) thresholds This would account for large decay widths to charmonium & the preference for some states to go to y’ & other J/y • S Dubynski et al • PLB 666,344 (2008) • FK Guo et al • PLB 665, 26 (2008) charmonium +excited light hadrons charmonium + gnd-state light hadrons

  37. Charmonium + (narrow) light hadron thresholds

  38. Scorecard • D(*)D(*) Molecules • favored for the X(3872) • but many XY states are not near thresholds • hybrids • no sign of open charm decays • diquarks-diantiquarks • No sign of SU(2)/SU(3) multiplet partners • Light-hadron charmonium bound states • not much coincidence between states & thresholds

  39. Candidates for XY counterparts in the b- and s-quark sectors

  40. Y(4260) equivalent with b-quarks? Belle s(e+e- p+p-(nS)) _ K.F. Chen et al (Belle) arXiv:0808.2445 Peaks not consistent with known bb states G(pp(nS)) ~ 1000x too large for conventional bottomonium

  41. Y(4260) equivalent with s-quarks? e+e-  g f0(980)f Y(2175)f0(980)f s(e+e- p+p-f(1020)) BaBar f0(980)p+p- M(f0(980)f) BaBar, PRD 74, 091103

  42. Confirmed by BES & Belle confirmed by BESII in J/y  h f f0(980) s(e+e- f0(980)f(1020)) BES Belle M(f0(980)f GeV C.P.Shen et al (Belle) arXiv: 0808.0006 NB: Radial excitation of the f is not ruled out M.Ablikim et al (BES) PRL 100, 102003 (2008)

  43. Do the X & Y mesons have electrically charged counterparts?

  44. The Z+ meson candidates BKp+y’ 6.5  Z(4430)+ M2(p±y’) GeV2 M(p±y’) GeV Not confirmed by BaBararXiv:0811.0564 Discussed by R.Chistov & C.Patrigani in the next session S.-K. Choi et al (Belle) PRl 100, 142001 M2(Kp’) GeV2 BKp+cc1 >6  Z2(4250)+ M(p±cc1) GeV M2(p±c’c1) GeV2 Z1(4050)+ M2(Kp’) GeV2 R.Mizuk,R.Chistov et al (Belle) PRD 78, 072004

  45. Concluding remarks _ • Lots of non-qq mesons candidates are seen • No single non-qq model explains them well • Recurring theme: large widths for decays to final states with charmonium _

  46. Winston Churchill & women v Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing ever happened. charm, Newinsights often Puzzles

  47. Thank you

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