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The hidden charm of hadrons

The hidden charm of hadrons. Stephen L. Olsen University of Hawai’i. Representing Belle. Invited talk at the Tampa APS/DPF meeting, April 19, 2005. test of QCD: “running” a s. Probe QCD from other directions. non-qq or non-qqq hadron spectroscopies: Pentaquarks: e.g. an S=+1 baryon

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The hidden charm of hadrons

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  1. The hidden charm of hadrons Stephen L. Olsen University of Hawai’i Representing Belle Invited talk at the Tampa APS/DPF meeting, April 19, 2005

  2. test of QCD: “running” as

  3. Probe QCD from other directions non-qq or non-qqq hadron spectroscopies: Pentaquarks: e.g. an S=+1 baryon Glueballs: gluon-gluon color singlet states Multi-quark mesons: qq-gluon hybrid mesons d u u d s u c u c c c

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

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

  6. Is the X(3872) non-standard? BK p+p-J/y y’p+p-J/y X(3872)p+p-J/y M(ppJ/y) –M(J/y)

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

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

  9. 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

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

  11. JPC possibilities (for J ≤ 2)

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

  13. Areas of investigation • Search for radiative decays • Angular correlations in XppJ/y decays • Fits to the M(pp) distribution • Search for X(3872)D0D0p0

  14. Search for X(3872)g J/y

  15. 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

  16. Select BKg J/y BKcc1; cc1g J/y X(3872)? M(gJ/y) Mbc Mbc 13.6 ± 4.4 X(3872)gJ/y evts (>4s significance) Bf(XgJ/y) Bf(XppJ/y) =0.14 ± 0.05

  17. Evidence for X(3872)p+p-p0 J/y(reported last summer hep-ex/0408116) A virtual w(782)? 12.4 ± 4.2 evts B-meson yields vs M(p+p-p0) Br(X3pJ/y) Br(X2pJ/y) Large (near max) Isospin violation!! = 1.0 ± 0.5

  18. C=+1 is established • Xg J/y only allowed for C=+1 • same for X”w”J/y (reported earlier) • M(pp) for Xp+p-J/y looks like a r CDF

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

  20. 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

  21. Use 253 fb-1  ~275M BB prsexploit the excellent S/N X(3872)p+p-J/y y’p+p-J/y Signal (47 ev) Sidebands (114/10 = 11.4 ev)

  22. 0++ In the limit where X(3872), pp, & J/y rest frames coincide: dG/dcosqlp sin2qlp qlp c2/dof = 34/9 |cosqlp| rule out 0++

  23. 0-+ c2/dof=18/9 0-+ : sin2q sin2y q |cosq| c2/dof=34/9 y |cosy| safe to rule out 0-+

  24. 1++ compute angles in X(3872) restframe 1++: sin2ql sin2c c2/dof = 11/9 ql K |cosql| c2/dof = 5/9 c |cosc| 1++ looks okay!

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

  26. Fits to the M(pp)Distribution J/y XrJ/y has a q*(2l+1) centrifugal barrier q* X q* r

  27. 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

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

  29. Search for X(3872)D0D0p0

  30. Select BKD0D0p0 events D*0D0p0? M(D0D0p0) 11.3±3.6 sig.evts (5.6s) Bf(BKX)Bf(XDDp)=2.2±0.7±0.4x10-4 Preliminary |DE| |DE|

  31. X(3872)DDp rules out 2++ • 1++ : DD* in an S-wave  q* • 2++ : DDp in a D-wave  q*5 Strong threshold suppression

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

  33. can it be a 1++ cc state? 1++ cc1’ • Mass is ~100 MeV off • cc1’  r J/y not allowed by isospin. Expect: Bf(cc1’ppJ/y)<0.1% BaBar measurement: Bf(XppJ/y)>4% 3872 -G(cc1’gJ/y) / G(cc1’ppJ/y) Expect: ~ 40 cc1’ component of X(3872) is ≤few % • G(X3872gJ/y) / G(X3872ppJ/y) • Measure: 0.14 ± 0.05

  34. Intriguing fact lowest mass charmed meson MX3872 =3872 ± 0.6 ± 0.5 MeV mD0 + m D0* = 3871.2 ± 1.0 MeV lowest mass spin=1 charmed meson X(3872) is very near DD* threshold. is it somehow related to that?

  35. D0D*0 bound state (deuson)? N. Tornqvist hep-ph/0308277 deuteron: deuson: attractive nuclear force attractive force?? c c p n D p D* p u u 2 loosely bound qqq color singlets with Md = mp+mn- e 2 loosely bound qq color singlets with M= mD + mD* - d

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

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

  38. 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

  39. BK wJ/y in Belle “Y(3940)” M≈3940 ± 11 MeV G≈ 92 ± 24 MeV Mbc Mbc Mbc S.K. Choi et al hep-ex/0408126 to appear in PRL

  40. 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

  41. 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)

  42. 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

  43. 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): • No obvious cc assignment • tetraquark seems unlikely • cc-gluon hybrid? c c ????? • - Lots to do: • determine JPC ; find other modes (DD*, DsDs, …?)

  44. Mahalo

  45. Back-up slides

  46. 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.

  47. M(gJ/y) look-back plot

  48. Fit cosqlp with 1++ MC c2/dof=11.9/9 |cosqlp|

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