CNRS-IN2P3, LAPP Annecy, Université de Savoie, France On behalf of the BaBar collaboration Moriond QCD, 24 March 2014 1
OUTLINE 9 GeV e - 3.1 GeV e + Recorded 531 fb -1 in total (4S): 433 fb -1 (3S): 30 fb -1 (2S): 14 fb -1 Off-peak: 54 fb -1 The experiment switched off in 2008, but still produces many interesting results! 529 papers in total 26 papers in 2013 Two new preliminary results presented today NEW! Study of B J/y K + K - K and search for B J/y 424 fb -1 NEW! Dalitz plot analyses of c K + K - and c K + K - 0 in two-photon interactions 519 fb -1 2
CHARMONIUM Charmonium: cc or cc-like Below the D (*) D (*) threshold Narrow width All states are observed and explained Above the D (*) D (*) threshold Large width expected Many unexpected states reported since 2003! Some of them narrow X(4140) Several exotic hypothesis Tetraquarks Hadronic molecules Hybrids Glueball 3
result (not yet on arxiv) 4
MOTIVATION 2009 + 2011 CDF studied the decay mode B + J/y K +, K + K -, J/y + - Looked at J/y invariant mass Observed two narrow peaks, named X(4140) and X(4270) PRL102, 242002 (2009) arxiv:1101.6058 (2011) > 5 3.1 6.0 fb -1 0.37 fb -1 2012 LHCb did not confirm these peaks 2.4 disagreement with CDF CDF peaks PRD85, 091103 (2012) 5
2013 CMS confirmed the presence of the two resonances arxiv:1309.6920 (2013) MOTIVATION > 5 5.2 fb -1 2014 D0 saw evidence for the two resonances PRD89, 012004 (2014) 3.1 1.7 10.4 fb -1 6
MOTIVATION 650 fb -1 Nota: 2009 Belle did the study (unpublished) Lepton-Photon conference 2009 Unable to conclude due to low efficiency at threshold 1.9 Summary of the previous results 7
ANALYSIS 424 fb -1 Study of the processes B + J/y K + K - K +, B 0 J/y K + K - K 0 S, and B 0 J/y J/y e + e -, + - K + K - Perform the branching fraction measurements Search for the resonances X(4140) and X(4270) Search for the suppressed decay B 0 J/y B + J/y K + K - K + B 0 J/y K + K - K 0 S Branching fraction measurement Fit to the m ES distributions After selection After selection 8
BRANCHING FRACTIONS Observation of a clear K + K - signal B + J/y K + K - K + Sideband B 0 J/y K + K - K 0 S Sideband Yields and branching fractions Values in agreement with previous BaBar measurement No measurements by other experiments Ratio of the resonant and nonresonant BF in agreement with predictions from spectator quark model 9
SEARCH FOR RESONANCES Study of the J/y mass spectrum in B J/y K Ingredients Signal: two incoherent Breit-Wigner distributions with parameters fixed to CDF values arxiv:1101.6058 (2011) 2D efficiency map taken into account in the fit Background: uniform distribution (phase space) B + J/y K + Result of the fit Fit with the two CDF resonances 2 /NDF = 17.2/13 Fit with no resonances 2 /NDF = 24.0/15 < 2.9 Phase space (no resonances) Sideband 10
SEARCH FOR RESONANCES Fit fractions with the assumption of two resonances f(4140) = (7.3 2.5 3.8)%; UL(90% CL) = 12.1% f(4270) = (7.7 3.7 5.2)%; UL(90% CL) = 16.4% Comparison to other experiments (*) Estimated from number of signal events quoted No clear conclusion from BaBar on these resonances Lack of statistics Need a full Dalitz plot analysis 11
SEARCH FOR THE DECAY B 0 J/y Decay B 0 J/y expected to be suppressed No signal seen in the channel B 0 J/y Signal region: 6 4 events BF(B 0 J/y ) < 1.01 10-6 @ 90% CL To be compared to Belle: BF(B 0 J/y ) < 0.94 10-6 @ 90% CL LHCb: BF(B 0 J/y ) < 0.19 10-6 @ 90% CL PRD 78, 011106 (2008) PRD 88, 072005 (2013) 12
result (about to be submitted) 13
ANALYSIS STRATEGY Using 519 fb -1, we study the reactions 1* 2* K + K - with, + - 0, and 1* 2* K + K - 0 Outgoing e + and e - produced at low angle (not detected) i * are quasi-real Two photon reaction can produce c or c (2S) Full Dalitz plot analyses of the decays c K + K - and c K + K - 0 are performed 14
MOTIVATION Many c and c (2S) decays are still missing BF( c ) ~ 20% BF( c (2S)) < 5% PRD86, 010001 (2012) BESIII studied these modes with low statistics N( c K + K - ) = 6.7 3.2 events N( c K + K - 0 ) = 54.9 9.2 events PRD86, 092009 (2012) No Dalitz plot analysis has been published for c decays to three pseudo-scalar mesons This study brings more information on poorly known scalar states and is sensitive to new gluonic states 15
Nice signal found in the two channels c K + K - : 1145 events First observation! c (2S) K + K - : 47 events First evidence! c K + K - 0 : 4518 events c (2S) K + K - 0 : 178 events Fit parameter values MASS SPECTRA c K + K - K + K - 0 519 fb -1 c (2S) c c (2S) 16
BRANCHING RATIOS Weighted mean of the BR values for the two c decay modes BESIII: 0.46 0.24 For the c (2S) decay modes PRD86, 092009 (2012) 17
DALITZ PLOT FOR c K + K - f 0 (980) f 0 (1500) f 0 (1710) f 0 (2200) K * 0(1430) Sideband f 0 (1500) and f 0 (1710) are gluonium candidates First evidence of the decay K * 0(1430) K and first time this particle seen as a peak! K * 0(1430) 18
DALITZ PLOT FOR c K + K - 0 a 0 (1450) K * 0(1430) Sideband The K 0 mass spectrum is dominated by the K * 0(1430) resonance K * 0(1430) 19
K * 0(1430) Obtaining the best-fit parameters using a likelihood scan during the Dalitz plot analysis of c K + K - 0 m(k * 0(1430)) = 1438 8 4 MeV/c 2 Good agreement with LASS experiment (K * 0(1430)) = 210 20 12 MeV 3 smaller than the LASS result Nucl. Phys. B296, 493 (1988) Branching ratio 20
SUMMARY New results on the B J/y (K) channel Branching fractions and ratios measured X(4140) and X(4270): no definitive conclusion on their existence No significant signal found in B J/y New results on c K + K - and c K + K - 0 Large signal seen in both channels First observation of c K + K - and first evidence for c (2S) K + K - First Dalitz plot analysis of these decays Large contribution from c f 0 (1500) First observation of the decay K * 0(1430) K and first time this particle seen as a peak 21
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Common analysis techniques 23
B J/y K + K - K 24
B J/y K + K - K 25