1 / 26

Recent results on quarkonium spectroscopy from BaBar and Belle

Recent results on quarkonium spectroscopy from BaBar and Belle. Bryan Fulsom SLAC National Accelerator Laboratory XXIII iemes Rencontres de Blois Blois, France June 1, 2011. Quarkonium Spectroscopy. Heavy quark (q=c,b) bound system: qq Existence, masses, widths, quantum numbers

lynne
Télécharger la présentation

Recent results on quarkonium spectroscopy from BaBar and Belle

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. Recent results onquarkonium spectroscopyfrom BaBar and Belle Bryan Fulsom SLAC National Accelerator Laboratory XXIIIiemes Rencontres de Blois Blois, France June 1, 2011

  2. Quarkonium Spectroscopy Heavy quark (q=c,b) bound system: qq Existence, masses, widths, quantum numbers Phenomenological models, effective field theory, lattice QCD BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 2/26

  3. The Experiments BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 3/26 Operated over the past decade, accumulating ~1.5 ab-1 Quarkonium production via B/(nS) decay, gg, ISR

  4. Topics covered today • Decay of X(3872)  p+p- J/y • X(3872) mass, width and BF measurements • Radiative decays of the X(3872) • Search for X(3872)  g J/y and g y(2S) • Recoil against p+p- in (3S) • b(2P)p+p-b(1P) transitions, (3S) mass, hb(1P) search • Recoil against po in (2S) • First evidence for hb(1P) • Bottomonium transitions with converted photons • Radiative decays of (nS) and b(nP), hb(1S) search BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 4/26

  5. Topics not covered today BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 5/26

  6. X(3872) BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 6/26

  7. X(3872) • Discovered by Belle in B± X K±, X  J/yp+p- • Since measured by BaBar, CDF, DØ, LHC • Also decays to DD*, J/yw, and gy • JPC assignment 1++ or 2-+ • DD* molecule, charmonium, or tetraquark? • Mass, width, decays, rates can test these theories • Mass above or below DD* threshold? • Tetraquark predicts splitting between neutral and charged B decay • Width • Narrow, best limit G<2.3 MeV • Decay rates • Ratio of neutral to charged (~1 for cc, ~0.1 for molecule) BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 7/26

  8. X(3872)  J/yp+p- Update Full Belle dataset Reconstruct B  X(3872) K, X(3872)  J/y(l+l-) p+p- Perform 3D fit to mBC, DE, m(J/yp+p-) BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 8/26

  9. X(3872)  J/yp+p- Results • Most precise measurements of branching fraction and mass • Mass splitting disfavors tetraquark hypothesis • BF ratio consistent with previous BaBar results • R = (0.41 ± 0.24 ± 0.05) • Best limit on width • m(X(3872)) world average gives “binding energy” of ~0.12 ± 0.35 MeV BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 9/26

  10. X(3872) gJ/y, gy(2S) • BaBar evidence (~3.5s) for X(3872) decaying to gJ/y and gy(2S) • Analyze same decay channel with ~2x amount of data • Reconstruction • J/y  l+l-, y(2S)  l+l-, y(2S)  J/yp+p- final states • Combine with g to produce cc1,2(1P) and X(3872) candidates • Add K± or KSo to form B± and Bo candidates BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 10/26

  11. ccJ  g J/y • Verify signal extraction technique on B  ccJ K, ccJ  g J/y • Good agreement with PDG • First measurement of suppressed B±  cc2 K± decays BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 11/26

  12. X(3872) g J/y • Simultaneous fit of K± and KSo modes • First “observation” (5.5s) of X(3872)  g J/y • Confirms C = + • Most precise measurement of branching fractions; agrees with BaBar • B(B  X(3872) K)  B(X(3872)  g J/y) = (1.8 ± 0.5 ± 0.1)  10-6 BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 12/26

  13. X(3872) g y(2S) • Combine y(2S)K with any p± or po in the event and veto if it is consistent with B  y(2S)K* decay • Fit g y(2S) distribution with three components: • Peaking (MC), non-peaking (sidebands/MC), signal • No evidence for X(3872)  g y(2S) signal • Ratio [X(3872)  g y(2S)] / [X(3872)  g J/y] < 2.1 • Compared to R = 3.4 ± 1.4 from BaBar BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 13/26

  14. Bottomonium BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 14/26

  15. Dipion Recoil in (3S) • Analysis goal: search for Y(3S)  p+p- hb(1P) • Define p+p- recoil mass: mR2 = (m(3S) – E*p+p-)2 – |P*p+p-|2 • 2 fit to mR • Peaking components • (3S)  p+p- hb signal • (3S)  p+p- (2S) • (2S)  p+p- (1S) • b1,2(2P)  p+p- b1,2(1P) • Smooth backgrounds • KSo  p+p- • Non-peaking background BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 15/26

  16. Dipion Recoil Fit Result BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 16/26

  17. Dipion Recoil Summary • No evidence for hb: B((3S)  p+p- hb(1P)) < 1.8  10-4 • Precision measurements • First observation of cb1,2(2P)  p+p- cb1,2 (1P) transitions BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 17/26

  18. Search for hb(1P) • Analysis Strategy • Search for (3S)  po hb(1P) • Reconstruct po(g1g2) + g • Require Eg consistent with hb(1P)  ghb(1S) • Assume B(hb(1P)  ghb(1S))  41% • Define po missing mass: m.m.(po)2 = (m(3S) – E*po)2 – P*po2 • Npo from mg1g2 fit in each m.m.(po) bin • 2 fit of m.m.(po) distribution • hb(1P) signal: Double Crystal Ball • Background: 6th order polynomial BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 18/26

  19. Y(3S)pohb(1P)(ghb(1S)) BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 19/26

  20. Evidence for hb(1P) • Measured mass agrees with expectation • mhb(1P) = (mcb0(1P)+3mcb1(1P)+5mcb2(1P)) / 9  9900 MeV/c2 • Branching fraction consistent with theory • First evidence for hb(1P), definitively confirmed by Belle BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 20/26

  21. Radiative Transitions • Radiative bottomonium transitions • Rates generally phenomenologically well-predicted • Gateway to discovery (e.g.: (nS)  ghb(1S)) • Use converted photons (g  e+e-) improve resolution (e.g.: 25  5 MeV) • Reconstruct pair of tracks, selected with c2fitter, mg, rg • Additional cuts: |cosqthrust|, Ntracks, poveto • Fit Eg* spectrum in four regions of interest • Goals: Resolve Eg* spectrum to make precision measurements BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 21/26

  22. (3S) : 180<Eg*<300 MeV Three “signal” transitions (bJ(2P)  g(2S)) and six (1D)-related lines Precision measurements of BF(bJ(2P)  g(2S)) BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 22/26

  23. (3S) : 300<Eg*<600 MeV • Complicated photon spectrum: many overlapping signals • Observation and precise measurement of (3S)  g b0,2(1P) transitions • Transition rate pattern J = 2 > 0 > 1 unusual for quarkonium BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 23/26

  24. (2S) : 300<Eg*<800 MeV • Measure bJ(1P)  g(1S) and search for hb(1S) signal • Due to high bkgd/low eff., no evidence for (2S)  ghb(1S) BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 24/26

  25. (3S) : 600<Eg*<1100 MeV • Measure bJ(2P)  g(1S) and search for hb(1S) signal • Eg* for hb(1S) is lower than expected, but significance is ~2.7s • Need more data to take full advantage of converted photon technique BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 25/26

  26. Summary • X(3872) at Belle • Improved measurements of X(3872) properties • Observation of X(3872)  g J/y, disagreement on X(3872)  g y(2S) • Even after ~10 years, still haven’t solved the X(3872) problem! • Bottomonium studies at BaBar • Evidence for hb(1P) in Y(3S)  po hb(1P) decays • Precision measurements of masses and dipion and radiative transitions offer important tests for theoretical models • B-Factories have revitalized field of quarkonium spectroscopy • Many new measurements and discoveries of puzzling new states • Very promising future at Belle-II and SuperB BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / 2011.06.01 / Page 26/26

More Related