5th International Conference on Hyperons, Charm and Beauty Hadrons, Vancouver David Waller, Carleton University Ottawa, Canada Semileptonic BR of b hadrons and charm counting at LEP

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 2 Introduction to BR sl and n c Latest LEP BR sl result (ALEPH) Latest LEP n c result (DELPHI) Compare Z 0 and Upsilon(4S) results, and experiment to theory Conclusions and outlook Outline

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 3 Introduction to BR sl and n c Precise calculations and measurements of BR sl possible. Experimental results for BR sl at low end of theoretical expectations BR sl  if  hadronic   hadronic related to n c. n c = average # of c and c per b decay measure BR 0c and BR 2c

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 4 2 separate analyses  results combined –analysis A: uses lepton momentum transverse to jet axis ( p T ) –analysis B: uses correlation between charge of lepton and estimated b flavour of hemisphere. P sample: high p T lepton (p T > 1.25 GeV/c) in opposite hemisphere estimates flavour of b.. J sample: 2 hemisphere charge estimators (similar to “jet charge”) from opposite hemisphere combined (Q H ) to estimate flavour of b. Electron and Muon ID: TPC pad pulse height used to help estimate dE/dx (previously only TPC wire info used). Efficiency , especially for lower p T electrons (+30%). TPC pad and wire dE/dx information combined. Latest BR sl measurement from LEP (ALEPH)

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 5 BR(b  l X): p T Analysis (using B sample) Likelihood fit used to determine fractions of b  l and b  c  l in data. BR(b  l X) and BR(b  c  l X) determined from fractions and detection efficiencies.

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 6 BR(b  l X): p T Results Lepton p T modelling dominates uncertainty (“model” uncertainty). –Fractions of D, D *, D 1, and D 2 * in final state (and 3- and 4-body decays) varied. –ACCMM, ISGW, ISGW * * models not used. –Uncertainty in lepton p T spectrum dominated by proportions of final states, not models used for each final state. BR(b  l X) =  stat  syst  model BR(b  c  l X) =  stat  syst  model Statistical correlation = -0.45

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 7 BR(b  l X): Charge Correlation Analysis Sample P: high p T lepton b flavour/charge estimator, Q lepton  p T lepton. Sample J: “hemisphere charge” b flavour/charge estimator. Likelihood fit used to determine fractions (in each sample) of leptons with charge opposite to charge estimator of other hemisphere. exclude

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 8 BR(b  l X): Charge Correlation Result Less sensitive to b  l X kinematics modelling. Uncertainty from b  W  c  l rate dominates (produces same sign lepton as b  l ). BR(b  l X) =  stat  syst  model BR(b  c  l X) =  stat  syst model model Statistical correlation = BR(b  l X) =  stat  syst  model p T & Q Corr. Combined: Eur. Phys. J. C 22 (2002) 613.

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 9 BR(b  l X): Other LEP Results LEPEWWG fit (2001) of heavy flavour measurements at the Z gives Level of sophistication has increased over years (7 years since LEP 1!) and uncertainties have decreased. BR(b  l X)=   BR(b  l X) PDG 2000 =  LEP and

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 10 Latest n c analysis from LEP (DELPHI) Measures wrong sign (WS) charm production in b decays. WS D hadrons (e.g. b  D + X) produced almost exclusively in b  DDX decays (input for n c ). D +, D 0, and D s + are exclusively reconstructed. preliminary

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 11 Latest n c analysis from LEP (DELPHI) p D determined in b centre-of- mass frame. Flavour of c quark in D (s) determined by charge of K(  ). Flavour of b quark at decay time estimated using ANN (0 to 1) combining: –weighted track charges of opposite hemisphere. –weighted track charges of same hemisphere (excluding D tracks). Y(D)= ANN (D) or 1-ANN (D) preliminary

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 12 Latest n c analysis from LEP (DELPHI) For D s +, binned likelihood fit of Y(D) distribution determines numbers of WS and RS D s +. For D 0 and D + need p D also to determine numbers of WS and RS D (2-d fit). WS D 0 and D + suppressed compared to WS D s +. preliminary

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 13 Latest n c result from LEP (DELPHI, preliminary) Combine measured N WS and N RS D hadrons, BR(b  D,DX) from previously combined results (PDG), and acceptance correction (  WS /  RS ) to get WS BR’s. BR(b  D 0 X) + BR(b  D - X) = (9.3  1.7 stat  1.3 syst  0.4 BR(D  K  (  )) )% BR(b  D s - X) = (10.1  1.0 stat  0.6 syst  2.8 BR(D s -  KK  ) )%

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 14 Comparisons Z 0 and CLEO results are consistent for n c and BR(b  l X). Experimental results are consistent with theory but suggest low  (renormalization scale). This means NNLO calculations should be done (only NLO right now). Further improvements to n c will help pin down m c. 2001

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 15 Conclusions and Outlook Many LEP analyses have measured n c and BR(b  l X). –Only latest ones presented here. –Could not do justice to all in short time (apologies)! LEP data consistent with CLEO data and theory (Neubert, et al.) but maybe NNLO calculations needed to be safe (?). See theory BR(b  l X) talks later this week... DELPHI wrong sign charm result to be finalized. New OPAL n c result nearing completion (Fall 2002). To come...

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 16 ALEPH lepton energy spectrum

June 25, 2002David Waller, Carleton University BEACH 2002, Vancouver 17 Other n c results from LEP Previous LEP n c results obtained using: – exclusive reconstruction of D +, D 0, D s + and c-baryons, “classic” charm counting (OPAL,DELPHI,ALEPH) –inclusive measurement using decay topology to separate 0c, 1c and 2c b decays (DELPHI) –exclusive reconstruction of D and D in b decays to (partially) determine BR(b  DDX) (ALEPH)