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

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

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

Decay of X(3872)      J/  –X(3872) mass, width and BF measurements Radiative decays of the X(3872) –Search for X(3872)   J/  and  (2S) Recoil against     in  (3S) –  b (2P)      b (1P) transitions,  (3S) mass, h b (1P) search Recoil against   in  (2S) –First evidence for h b (1P) Bottomonium transitions with converted photons –Radiative decays of  (nS) and  b (nP),  b (1S) search Topics covered today BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 4/26

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

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

Discovered by Belle in B ±  X K ±, X  J/      –Since measured by BaBar, CDF, DØ, LHC –Also decays to DD*, J/ , and  –J PC 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  <2.3 MeV Decay rates –Ratio of neutral to charged (~1 for cc, ~0.1 for molecule) X(3872) BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 7/26

Full Belle dataset Reconstruct B  X(3872) K, X(3872)  J/  ( l + l - )     Perform 3D fit to m BC,  E, m(J/      ) X(3872)  J/      Update BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 8/26

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 X(3872)  J/      Results BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 9/26 PropertyValue BF(B +  K + X) x BF(X  J/      ) (8.6±0.8±0.8) x BF(B 0  K 0 X) x BF(X  J/      ) (4.3±1.2±0.4) x Ratio (B + /B 0 )0.50±0.14±0.04  M = mX(B + ) – mX(B 0 ) -0.7±1.0±0.1 MeV M(X(3872))3871.8±0.3±0.2 MeV  (X(3872)) <1.2 MeV

BaBar evidence (~3.5  ) for X(3872) decaying to  J/  and  (2S) Analyze same decay channel with ~2x amount of data Reconstruction –J/  l + l -,  (2S)  l + l -,  (2S)  J/      final states –Combine with  to produce  c1,2 (1P) and X(3872) candidates –Add K ± or K S  to form B ± and B  candidates X(3872)   J/ ,  (2S) BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 10/26

Verify signal extraction technique on B   cJ K,  cJ   J/  Good agreement with PDG First measurement of suppressed B ±   c2 K ± decays  cJ   J/  BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 11/26

Simultaneous fit of K ± and K S o modes First “observation” (5.5  ) of X(3872)   J/  Confirms C = + Most precise measurement of branching fractions; agrees with BaBar –B (B  X(3872) K)  B (X(3872)   J/  ) = (1.8 ± 0.5 ± 0.1)  X(3872)   J/  BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 12/26

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

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

Analysis goal: search for Y(3S)      h b (1P) Define     recoil mass: m R 2 = (m  (3S) – E      ) 2 – |P      | 2  2 fit to m R Peaking components –  (3S)      h b signal –  (3S)       (2S) –  (2S)       (1S) –  b1,2 (2P)       b1,2 (1P) Smooth backgrounds –K S       –Non-peaking background Dipion Recoil in  (3S) BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 15/26

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

No evidence for h b : B (  (3S)      h b (1P)) < 1.8  Precision measurements First observation of  b1,2 (2P)       b1,2 (1P) transitions Dipion Recoil Summary BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 17/26

Analysis Strategy –Search for  (3S)    h b (1P) –Reconstruct   (     ) +  –Require E  consistent with h b (1P)   b (1S) –Assume B (h b (1P)    b (1S))  41% Define   missing mass: m.m.(   ) 2 = (m  (3S) – E    ) 2 – P    2 –N   from m     fit in each m.m.(   ) bin  2 fit of m.m.(   ) distribution –h b (1P) signal: Double Crystal Ball –Background: 6 th order polynomial Search for h b (1P) BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 18/26

Y(3S)   h b (1P)(   b (1S)) BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 19/26

Measured mass agrees with expectation –m h b (1P) = (m  b0 (1P) +3m  b1 (1P) +5m  b2 (1P) ) / 9  9900 MeV/c 2 Branching fraction consistent with theory First evidence for h b (1P), definitively confirmed by Belle Evidence for h b (1P) BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 20/26 PropertyValue Yield9145±2804±1082 evts. Significance 3.0  M [h b (1P)]9902±4±1 MeV/c 2 BF(Y(3S)   h b ) x BF(h b  b ) (3.7±1.1±0.7) x 10 -4

Radiative bottomonium transitions –Rates generally phenomenologically well-predicted –Gateway to discovery (e.g.:  (nS)    b (1S)) Use converted photons (   e  e  ) improve resolution (e.g.: 25  5 MeV) –Reconstruct pair of tracks, selected with  2 fitter, m ,   –Additional cuts: |cos  thrust |, N tracks,    veto –Fit E  * spectrum in four regions of interest Goals: Resolve E  * spectrum to make precision measurements Radiative Transitions BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 21/26

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

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

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

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

X(3872) at Belle –Improved measurements of X(3872) properties –Observation of X(3872)   J/ , disagreement on X(3872)   (2S) –Even after ~10 years, still haven’t solved the X(3872) problem! Bottomonium studies at BaBar –Evidence for h b (1P) in Y(3S)    h b (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 Summary BaBar/Belle Quarkonium Spectroscopy / Bryan Fulsom / Rencontres de Blois / / Page 26/26