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Exploring Non-Standard Mesons: Pentaquarks, Glueballs, and Multi-Quark States

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This seminar by Stephen L. Olsen at Fermilab on May 10, 2005, delves into the intriguing world of non-standard mesons, highlighting pentaquarks, glueballs, and multi-quark states. It discusses their existence based on various experimental findings, including noteworthy positive signals amidst negative results across numerous collaborations. Topics include the recent findings on states like DsJ(2317) and X(3872), as well as the role of Quantum Chromodynamics (QCD) in understanding these exotic particles. The session aims to shed light on the evolving landscape of hadron spectroscopy and the new physics it may reveal.

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  1. Non-standard mesons Stephen L. Olsen University of Hawai’i Representing Belle Fermilab seminar May 10, 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. 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. Existence of Pentaquarksis not yet established

  7. Narrow multi-quark mesons? • DsJ(2317) & DsJ(2457) • X(3872)ppJ/y CLEO BaBar M(Ds*p) M(Dsp) Belle M(ppJ/y)

  8. What are the DsJ states? Belle found B D DsJ(2317)  D DsJ(2457) and DsJ(2457)gDs

  9. J=1 J=1 J=0 J=2 Angular analysis for B D DsJ DsJDsp(g) J=0 z Jz=0 (p) DsJ(2460) Ds  DsJ(2317) Ds0 DsJ(2317) = 0+ DsJ(2547) = 1+

  10. DsJ fit into cs spectrum(with a mass shift) DsJ(2547) = 1+ DsJ(2317) = 0+

  11. DsJ states are likelyordinary L=1 cs mesons(with perhaps some tetraquark mixture) Potential models got the masses wrong Chiral models seem to work OK See, e.g. Bardeen, Eichten & Hill PRD68, 054024

  12. 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

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

  14. 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)

  15. Its existence is well establishedseen in 4 experiments PRL 93, 072001 CDF 9.4s 11.6s X(3872) PRL 93, 162002 D0 PRD 71, 071103(R) X(3872) hep-ex/0406022

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

  17. 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

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

  19. JPC possibilities (for J ≤ 2)

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

  21. 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

  22. Search for X(3872)g J/y

  23. 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

  24. 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

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

  26. 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

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

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

  29. 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)

  30. Example: 1-- J/y y’ Use BK y’ K z y’is 1-- dN/dcosq  sin2qKm pp y’: c2/dof = 8.9/9 qKm K compute angles in J/y restframe D.V. Bugg hep-ph/0410168v2

  31. |cosqKl| for X(3872) events c2/dof = 60.3/9 fit with sin2qKl + bkgd see 8 evts/bin expect 2~3evts/bin background scaled from sidebands X(3872) is not 1-- !

  32. 0++ M eJ/y·er In the limit where X(3872), pp, & J/y rest frames coincide: dN/dcosqlp sin2qlp qlp c2/dof = 34/9 rule out 0++ |cosqlp|

  33. 0-+ M  pJ/y· (eJ/yxer) c2/dof=18/9 0-+ : sin2q sin2y q |cosq| c2/dof=34/9 y |cosy| safe to rule out 0-+

  34. 1++ M | eX xeJ/yxer| dN/dcosqdcosc sin2ql sin2c c2/dof = 11/9 ql K |cosql| c c2/dof = 5/9 1++ looks okay! |cosc| compute angles in X(3872) restframe

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

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

  37. 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

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

  39. X(3872)D0D0p0?

  40. 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|

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

  42. Eliminate all other factors and the one which remains must be the truth Sherlock HolmesThe Sign of Four

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

  44. 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

  45. From BaBar: D(*)p+ e+e-B+B- K-X0 fully reconstructed Jon Coleman Moriond-QCD March 2005 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.

  46. 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?

  47. D0D*0 bound state (deuson)? Voloshin & Okun JETP Lett 23, 333 (1976) Bander et al PRL 36, 695(1976) DeRujula et al PRL 38, 317 (1977) Manohar & Wise, NP B339, 17 (1993) Tornqvist, Z Phys C61, 525(1994) 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

  48. 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)

  49. 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

  50. 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