1 / 53

Searches for exotic mesons

This talk discusses the searches for non-standard mesons, including multi-quark molecules and baryonium, as well as the findings on pentaquarks. It also explores the existence and properties of the X(3872) and Y(3940) mesons.

jcamp
Download Presentation

Searches for exotic mesons

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Searches for exotic mesons Stephen L. Olsen University of Hawai’i u c • Multi-quark molecules • qq-gluon hybrids • baryonium u c c c d u u u d u DOE site visit Aug 22, 2005

  2. test of QCD: “running” as

  3. Probe QCD from other directions non-qq or non-qqq hadron spectroscopies: Reawakened by the claims for Pentaquarks e.g. an S=+1 baryon d u u d s

  4. Pentaquarks? “Seen” in many experiments but not seen in just as many others Compass Jlab p BES Belle BaBar CDF High interest: 1st pentaquark paper has >500 citations

  5. Pentaquark Scoreboard Positive signals Negative results Also: Belle Compass L3 Jlab(CLAS) (gpK+Ksn) Yes: 17 No: 18

  6. This talk • Searches for non-standard mesons with hidden charm at Belle • Search for baryonium mesons at BES c c u c u c d u u u d u

  7. searches for non-standard mesons with “hidden charm” at Belle u c (i.e containing c & c) • standard cc mesons are: • best understood theoretically • narrow & non overlapping • c + c systems are commonly produced in B meson decays. u c c c c c Vcb b W- cosqC s CKM favored

  8. Thanks to KEKB, Belle has lots of B mesons(>1M BB pairs/day) >1fb -1/day Design: 10 34

  9. X(3872)p+p-J/y BK p+p-J/y y’p+p-J/y X(3872)p+p-J/y M(ppJ/y) –M(J/y) S.-K.Choi, S.L.Olsen et al (Belle) PRL 91 262001 (2003)

  10. Its existence is well establishedseen in 4 experiments CDF 9.4s 11.6s X(3872) D0 X(3872) hep-ex/0406022

  11. Is it a cc meson? Could it be one of these? 3872 MeV These states are already identified

  12. no obvious cc assignment hc” hc’ cc1’ y2 hc2 y3 M too low and G too small angular dist’n rules out 1+- 3872 G(gJ/y) way too small G(gcc1) too small;M(p+p-) wrong pp hc should dominate G( gcc2 & DD) too small SLO hep-ex/0407033

  13. go back to square 1 Determine JPC quantum numbers of the X(3872) with minimal assumptions

  14. JPC possibilities (for J ≤ 2)

  15. JPC possibilities0-- ruled out; JP=0+,1- & 2+ unlikely

  16. Strong evidence for C=+1 X(3872)gJ/y X(3872)p+p-p0J/y 12.4 ± 4.2 evts virtual w(782)? M(p+p-p0) Br(X3pJ/y) Br(X2pJ/y) = 1.0 ± 0.5 13.6 ± 4.4 X(3872)gJ/y evts (>4s significance) X(3872)p+p-J/y Bf(XgJ/y) Bf(XppJ/y) =0.14 ± 0.05 Fits to r(760) M(p+p-)

  17. JPC possibilities (C=-1 ruled out)

  18. Angular Correlations r Jz=0 J=0 X3872 J=0 K z Rosner (PRD 70 094023) Bugg (PRD 71 016006) Suzuki, Pakvasa (PLB 579 67) J/y

  19. 0++ 0-+ q qlp y c2/dof=18/9 c2/dof = 34/9 |cosq| c2/dof=34/9 |cosqlp| rule out 0++ & 0 -+ |cosy|

  20. JPC possibilities (0-+ & 0++ ruled out)

  21. M(pp) can distinguish r-J/y S- & P-waves P-wave: c2/dof = 71/39 S-wave: c2/dof = 43/39 (CL=0.1%) (CL= 28%) q* roll-off q*3 roll-off Shape of M(pp) distribution near the kinematic limit favors S-wave

  22. Possible JPC values (J-+ ruled out)

  23. X(3872)D0D0p0 ? D*0D0p0? • 1++ : DD* in an S-wave  q* • 2++ : DDp in a D-wave  q*5 Strong threshold suppression M(D0D0p0) 11.3±3.6 sig.evts (>4s) Bf(BKX)Bf(XDDp)=2.2±0.7±0.4x10-4

  24. Possible JPC values (2++ ruled out) 1++ 1++

  25. can it be a 1++ cc state? 1++cc1’ Mass is too low 3872 Bf(Xp+p- J/y)>4% is too large p+p- (Isospin forbidden) cc1’ component of X(3872) is ≤ few%

  26. Intriguing fact lowest mass charmed meson lowest mass spin=1 charmed meson MX3872 =3872 ± 0.6 ± 0.5 MeV mD0 + m D0* = 3871.2 ± 1.0 MeV Deuson? deuteron-like DD* bound state? 2 loosely bound qq color singlets with M= mD + mD* - d c c D p D* u u one p exchange attractive for 1++ Tornqvist PLB 590, 209 (2004)

  27. X(3872) = D0D*0 bound state? • JPC = 1++ is favored • M ≈ mD0 + mD0* • Large isospin violation is natural (& was predicted):  |D0D*0> = 1/2(|10> - |00>) • G(XgJ/y) < G(XppJ/y) was predicted • G(XD0D0p0) too large? Tornqvist PLB 590, 209 (2004) Equal mixture of I=1 & I =0 Swanson PLB 588, 189 (2004) Swanson PLB 598, 197 (2004)

  28. X(3872) conclusion • JPC = 1++ • cc content is small • matches most expectations for a D0D*0 bound state C C u c u c a non-qq meson

  29. Are there others?Is the X(3872) a one-of-a-kind curiousity? or the 1st entry in a new spectroscopy? Look at other B decays  hadrons+J/y: BK h J/y BK p J/y BK w J/y

  30. BK wJ/y in Belle “Y(3940)” M≈3940 ± 11 MeV G≈ 92 ± 24 MeV Mbc Mbc Mbc M(wJ/y) MeV S.K. Choi & S.L.Olsen et al. (Belle), PRL94, 182002 (2005)

  31. Y(3940): What is it? Brambilla et al (QWG) hep-ph/0412158 • Charmonium? • Conventional wisdom: wJ/y should not be a discovery mode for a cc state with mass above DD & DD* threshold! • Some kind of w-J/y threshold interaction? • the J/y is not surrounded by brown muck; can it act like an ordinary hadron? w J/y

  32. Y(3940): What is it (cont’d)? • another tetraquark? • M ≈ 2mDs • not seen in YhJ/y • (h contains ss) • width too large?? • no p exchange for DSDS c s s c ?? PRL 93, 041801 M(h J/y)

  33. Y(3940): What is it (cont’d) ? • cc-gluon hybrid? • predicted by QCD, • decays to DD and DD* are suppressed (“open-charm” thresh = mD + m D** = 4.3 GeV) • large hadron+J/y widths are predicted • masses expected to be 4.3 ~ 4.4 GeV (higher than what we see) c c Horn & Mandula PRD 17 898 (1974) + (many) others

  34. BaBar’s Y(4260) 211 fb-1data collected at √(s) = 10.58 GeV 11802110(2S) evts 12523Y(4260) evts (2S) Y(4260) M=4259  8 MeV G = 88  23 MeV J/ sideband B. Aubert et al. (BaBar) hep-ph/0506081 Well above DD & DD* threshold but found in an OZI-suppressed mode??

  35. cc summary • X(3872): • JPC established as 1++ • cc component is small (≤ few %) • all properties consistent with a D0D*0 bound state u c a non-standard meson u c • Y(3940) Belle, Y(4260) BaBar c c ????? • - Lots to do: • determine JPC ; find other modes (DD*, DsDs, …?)

  36. Hardronic charmonium transitions G(y’p+p-J/y) 70 keV G(y”p+p-J/y) 50 keV G(y’hJ/y)  5 keV SUF(3) violating HW (for theorists): How can G(Y3940)wJ/y) and G(Y(4260)p+p-J/y) be ~1000x larger? p+p- p+p- h

  37. Baryonium at BES??? d u u u d u

  38. Phys. Rev. Lett. 91, 022001 (2003) J/y g pp (at BES) acceptance weighted BW M(pp) +3 +5 -10 -25 M=1859 MeV/c2 G < 30 MeV/c2 (90% CL) 0 0.1 0.3 0.2 3-body phase space M(pp)-2mp (GeV)

  39. Baryonium potential & Wave fcn G.J. Dung & M.L. Yan hep-ph/0502127 Potential barrier “Rectangularized” Skyrmion-type potential I = 0, Jpc=0-+ pp annihilation M ~ 1860 MeV G ~ 16 MeV  large uncertainties -V0d(r) X  p+p- h’should be a strong channel

  40. M(p+p-h’) from J/y g p+p-h’ The +- mass spectrum for  decaying into +- and   7.7 M = 183463 MeV G = 68  20 8 MeV BESII Preliminary

  41. _ Re-fit to J/p p including FSI Include FSI curve from A.Sirbirtsev et al. ( Phys.Rev.D71:054010, 2005) in the fit (I=0) M = 1830.6  6.7 MeV  = < 153 MeV @90%C.L. In good agreement with X(1835)

  42. Appendix • Other new hidden charm particles from Belle (near 3940!) • X(3940) • Z(3931)

  43. Other new particles from Belle e+e-J/y + X

  44. X(3940)DD* seen(DD & wJ/y not seen)

  45. gg  Z(3931) DD at Belle sin4q (J=2) 4111 evts (5.5) M=3931 4  2 MeV =208 3 MeV

  46. Z(3931) = cc1’(almost for sure) ? X(3940)  Y(3940) (maybe the hc’’)

  47. Hawaii particles • hc’ • X(1860)(pp) • X(3872) • Y(3940)

  48. Back-up slides

  49. Jon Coleman Moriond-QCD March 2005 e+e-B+B- K-X0 244 fb-1 • Can measure absolute B.F.’s of B-K-X0 J/y Lower limit on BF(XJ/ypp) > 4.3% @ 90% C.L cc2 cc1 cc0 Very clear J/y and hc signals N J/y=258+- 42 N hc =266 +-42 • cc2,cc0<<cc1 • X(3872) production much lower than for other Charmonium states: • can set lower limit on B.F.

  50. Kinematic variables BK gJ/y Ecm/2 e+ e- B B ϒ(4S) Ecm/2 DE CM energy difference: BK gJ/y Beam-constrained mass: Mbc

More Related