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Semileptonic Branching Ratios and Moments

Semileptonic Branching Ratios and Moments. Giuseppe Della Ricca University and INFN – Trieste, Italy. 9 th International Conference on B Physics at Hadron Machines October 14-18, 2003 – Pittsburgh, PA, USA. n l. l -. W. b. u,c. V ub,cb. Motivations. semileptonic decays are

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Semileptonic Branching Ratios and Moments

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  1. Semileptonic Branching Ratiosand Moments Giuseppe Della Ricca University and INFN – Trieste, Italy 9th International Conference on B Physics at Hadron Machines October 14-18, 2003 – Pittsburgh, PA, USA

  2. nl l- W b u,c Vub,cb Motivations • semileptonic decays are • relatively simple theoretically at parton level • accessible experimentally • sensitive to quark couplings to W± (i.e. CKM matrix elements |Vub| and |Vcb|) • probe the dynamics of the decay • probe the impact of strong interactions • two possible approaches • exclusive measurements • need form-factors to describe the transition of the B meson to a lighter one • inclusive measurements • need OPE and b-quark mass to extract |Vxb| from the total rate Giuseppe Della Ricca – Semileptonic BRs and Moments

  3. Target in naïve spectator picture the process is analogous to muon decay but QCD (perturbative and non-perturbative) corrections are needed to extract weak decay physics comparison of results from different measurements provides a test of the consistency of OPE predictions and of underlying assumptions use many different approaches/techniques CKM’02 @ CERN Giuseppe Della Ricca – Semileptonic BRs and Moments

  4. Framework  sin2 Bd mixing: md kaon decays: εK Bs mixing: ms / md bul: |Vub| D*l: |Vcb|  measurements of |Vub| and |Vcb| provide stringent tests of the unitarity triangle Giuseppe Della Ricca – Semileptonic BRs and Moments

  5. Vcb or Vub Outline • exclusive measurements • BR(Be) [BaBar] • BR(Bl), BR(B“”l), BR(Bl) [BaBar, Belle, Cleo] • BR(BD*l) [BaBar] • BR(Bl) [Cleo] • BR(BD**0lX) [Opal] • inclusive measurements • <Mxn>, <Eln> in BXcl [BaBar, Cleo, Delphi] • BR(BXul) [BaBar] • DBR(BXul) [Belle] far too much interesting material to include in 20 min [apologies in advance] my own selection of recent result Giuseppe Della Ricca – Semileptonic BRs and Moments

  6. BR(B0r+e-n) [1] signal (ISGW2) HILEP HILEP crossfeed bue downfeed (ISGW2+DeFazio Neubert) E bce(HQET + Goity Roberts) M HILEP: 2.3< Eelectron<2.7 GeV (large continuum backgrounds) LOLEP: 2.0< Eelectron<2.3 GeV (large bce backgrounds) LOLEP LOLEP M E (B0-e+) = 2 (B+0e+) (B0p-e+) = 2 (B+p0e+) (B+0e+)= (B+e+) (isospin-constrained average of  and 0) Giuseppe Della Ricca – Semileptonic BRs and Moments

  7. BR(B0r+e-n) [2] extrapolate partial branching fraction to entire lepton-energy spectrum using five different form-factor calculations combined result: unweighted mean theoretical error on the combined result: full spread seen between the different form-factors combined result (unweighted mean): BR=(3.29  0.42  0.47  0.55 ) x 10-4 PRL 90 (2003) 181801 Giuseppe Della Ricca – Semileptonic BRs and Moments

  8. BR(B0ln,“r0”ln,ln) very high purity but small statistics loose cuts: small model dependence “0” : 0.65<m<0.95 GeV/c2 “r0” p0 w BR(B0l) = (0.78  0.32  0.13 ) x 10-4 BR(B“0”l) = (0.99  0.37  0.19 ) x 10-4 BR(Bl)= (2.20  0.92  0.57 ) x 10-4 preliminary new CLEO results: see next talk ! Giuseppe Della Ricca – Semileptonic BRs and Moments

  9. K ps D0 p B0 e/m BD*ln: motivations BD*ln represents 10% (5% e +5% m channel) of the total B0 decays, so a precise understanding of this decay improves the overall knowledge of the B branching ratios the study of the differential decay rate can be used to extract |Vcb| D*±  D0± D0  K, Ks, K0, K dM [= M(D*)-M(D0)] used to fit signal and background components (except D**) constrained vertex fit on D0 decay products, soft pion and lepton data control samples are used to estimate the background components (72 samples) Giuseppe Della Ricca – Semileptonic BRs and Moments

  10. Background characterization: fit to dM [= M(D*)-M(D0)] from data control samples uncorrelated continuum fake lepton fake D* Giuseppe Della Ricca – Semileptonic BRs and Moments

  11. Separation of D** component pmiss pn pB Dqmin qBY once other backgrounds are estimated from the global fit, B0(+) D*Xln events are separated using the angle between the B0 and the D*l direction. can be written as: D** shape different from the D* one fitted in each D0 mode and e/msubsample pY = pr + plept electrons-Kp mode D*ln (73.5%) D**ln (7.5%) Real D*, Fake (0.3%) Uncorrelated D* (6.2%) Correlated D*(1.5%) Continuum D*(3.2%) Fake D*(7.75%) if B0 D*ln if B0(+) D*Xln Giuseppe Della Ricca – Semileptonic BRs and Moments

  12. Results for BR(BD*ln) hep-ex/0308027 BR(B0D*-l+)= (4.69±0.02stat.data ±0.02stat.MC ±0.24syst.data)% comparison with other results Giuseppe Della Ricca – Semileptonic BRs and Moments

  13. D**0 are L=1 orbitally excited charm mesons narrow Jq= 3/2, Jp=1+,2+ states (D10, D2*0) wide Jq= 1/2, Jp=0+,1+ states (not visible with statistics) investigate the difference between measured inclusive and exclusive semileptonic branching ratios reduce uncertainty in |Vcb| test HQET predictions Orbitally excited D mesons (D**) motivation Giuseppe Della Ricca – Semileptonic BRs and Moments

  14. 3 mm Method • identify high p lepton (,e) • high efficiency and purity for p>3 GeV/c, pe>2 GeV/c • exclusively reconstruct D**0 D**0 D*+**- D0+slow K-+(+ -) • background cuts to remove fake **- ( from fragmentation) • main background from decays plus fake **- • ANN (p, pT, d0/σd0) to select **- Giuseppe Della Ricca – Semileptonic BRs and Moments

  15. D**0 – D*+ mass difference combine D0→ K and K3 channels to reduce uncertainty due to background unbinned ML fit to determine number of D1 and D2* events (B.-W.  Gaussian) number of wrong sign and right sign background events fit simultaneously CERN-EP-2002-094 Giuseppe Della Ricca – Semileptonic BRs and Moments

  16. Bo & B+ semileptonic decays accurate, separate BRsl for Bo & B+, tagged by fully reconstructing one B BR(B+Xln)/B(B0Xln)=1.140.040.01 preliminary Gsl(B+)/Gsl(Bo)=1.063±0.038 Giuseppe Della Ricca – Semileptonic BRs and Moments

  17. BR(BXe)= (10.890.08stat0.33syst)% Semileptonic B decays average BRsl on Y(4S), use high momentum lepton to tag flavor of 1st B CLEO preliminary, EPS’03 272 LEP(most recent EW fit)=(10.590.22)%10.76% at Y(4S) Giuseppe Della Ricca – Semileptonic BRs and Moments

  18. Parameters of HQE parameterization of decay rate in terms of Operator Product Expansion in HQET in powers of as(mb)b0 and L/mB: pole mass expansion - • L, l1, l2, are non-perturbative parameters • l1: (-) kinetic energy of the motion of the b-quark • l2:chromo-magnetic coupling of b-quark spin to gluon • (from B*-B mass difference, l2=0.12GeV2) • L= mB – mb + (l1 - 3l2)/2mB + … • + additional parameters enter at higher orders (r1, r2, t1, t2, t3, t4 ) • use theoretical estimates –1/mB3 - Giuseppe Della Ricca – Semileptonic BRs and Moments

  19. OPE parameter extraction first derivations of OPE parameters from spectral moments used the pole mass expansionand photon energy spectrum in B Xsg , hadronic mass spectrum and lepton energy spectrum in BXcln Eg MX2 El PRD 67 (2001) 072001 PRL 87 (2001) 251807 PRL 87 (2001) 251808 Giuseppe Della Ricca – Semileptonic BRs and Moments

  20. Moments of lepton energy spectrum and hadronic mass spectrum in Zbb events Z  qq signal: bb / hadrons  22% EB  0.7 Ebeam  30 GeV Bd0D**l decays exclusively reconstructed in three channels: D**D*+-, D0+, D+- l- * l K- D** * B + D0 - D + B  3mm first measurements of moments performed at LEP exploiting advantage of Z0 kinematics good secondary vertex reconstruction and signal/background separation Giuseppe Della Ricca – Semileptonic BRs and Moments

  21. Hadronic mass spectrum in B D**l D**D*+- D**D0+ D**D+- M = M(D(*)) - M(D(*)) distributions fitted including contributions of resonant (narrow, broad) and non resonant states, D*Xl floating BR(B0D**l)=(2.7  0.7  0.2) % DELPHI’03-28 Giuseppe Della Ricca – Semileptonic BRs and Moments

  22. Interpretations moments of hadronic mass spectrum and of lepton energy spectrum are sensitive to the non-perturbative parameters of the Heavy Quark Expansion. at order 1/mb2 , 1, 2 (20.12 GeV2) , at order1/mb31, 2,1-4 two possible approaches: 1) pole mass expansions (Falk, Luke, Gambino) 2) running quark masses (Bigi, Shifman, Uraltsev, Vainshtein) Giuseppe Della Ricca – Semileptonic BRs and Moments

  23. M1(Mx) M2(Mx) M3(Mx) M1(El) M2(El) M3(El) Pole mass scheme multi-parameter fit: r1(GeV3) l1(GeV2) L(GeV) L(GeV) good consistency of all measurements (c2/d.o.f.=0.4) results compatible with CLEO • L = 0.542 + 0.065fit+ 0.090sys GeV • l1=-0.238 + 0.055fit+ 0.030sysGeV2 • r1= 0.030 + 0.028fit+ 0.010sysGeV3 • r2= 0.066 + 0.025fit + 0.192sysGeV3 similar results with mb1S-l1 formalism applied to CLEO and DELPHI data (C.W.Bauer, Z.Ligeti, M.Luke, A.V.Manohar hep-ph/0210027) Giuseppe Della Ricca – Semileptonic BRs and Moments

  24. Non-perturbative parameter extraction makes use of low scale running quark masses and does not rely on a 1/mc expansion mb(m), mc(m) are independent parametersand two operators only contribute to 1/mb3 corrections :rD3, rLS3 first applied to fit DELPHI data • multi-parameter c2 fit to first three moments of lepton energy spectra and hadronic mass spectra (higher moments used to get sensitivity to 1/mb3parameters) • use expressions for non-truncated lepton spectra • simultaneous use of leptonic and hadronic moments in order to leave enough free parameters in the fit Phys. Lett. B556 (2003) 41 Giuseppe Della Ricca – Semileptonic BRs and Moments

  25. M1(Mx) M2(Mx) M3(Mx) M1(El) M2(El) M3(El) Kinetic mass scheme mp2 (GeV2) rD3 (GeV3) 4-parameter fit input constraints: mG2= 0.35 +0.05 GeV2 rLS3= -0.15 +0.15 GeV3 mc= 1.05  0.30 GeV mb= 4.57  0.10 GeV equivalent to that derived from Eg in B Xsg mb(GeV) mb(GeV) mb,kin(1GeV)= 4.570 +0.082fit +0.010sys GeV mc,kin(1GeV)= 1.133 +0.134fit +0.030sys GeV mp2 (1GeV) = 0.382 +0.070fit+0.030sys GeV2 rD3 (1GeV) = 0.089 +0.039fit+0.010sys GeV3 good consistency of all measurements (c2/d.o.f.=0.9) within present accuracy no need to introduce higher order terms to establish agreement with data Giuseppe Della Ricca – Semileptonic BRs and Moments

  26. Generalized energy moments 1s theoretical ellipse hep-ex/0212051 using ratios of truncated lepton spectra (Gremm et al. PRL77 20 ’96) • = 0.39±0.03stat±0.06sys±0.12th GeV • l1=-0.25±0.02stat±0.05sys±0.14th GeV2 parameters extracted from lepton spectra are in agreement with those extracted from MX2 and Eg Giuseppe Della Ricca – Semileptonic BRs and Moments

  27. <MX> ~ Hadronic mass moments [1] ~ measured MX differs from true MX for each interval in MX, full detector simulation gives < MX> and <MX> calibration curves applied to data: no model dependence ! pmin* dependence study non-res D** ~ D* D <MX>TRUE <MX> <MX2-mb2> pmin* pmin* Giuseppe Della Ricca – Semileptonic BRs and Moments

  28. Hadronic mass moments [2] fit OPE for <MX2> to data and extract the two leading HQE parameters and 1 (MS scheme)  all correlations taken into account _ CLEO bs <MX2> OPE fit OPE prediction using CLEO data only <Mx2> and <E> from bs pmin* all hadron mass moments are consistent (overlap from bands and BABAR ellipse) but 2=1 contour does not overlap with <E> band from CLEO bs Giuseppe Della Ricca – Semileptonic BRs and Moments

  29. Hadronic mass moments [3] extraction of mb1s, and 11sfrom a fit to the HQE in the 1s mass scheme (O(1/mb3) parameters are fixed in the fit) 2=1 contour of hadron moments and lepton moments do not overlap indication for large O(1/mb3) corrections, duality violation, or maybe even more …? hep-ex/0307046 Giuseppe Della Ricca – Semileptonic BRs and Moments

  30. Hadronic mass moments the neutrino 4-vector is inferred using the detector hermeticity <M2X - M2D>El>1.0 GeV = 0.456±0.014±0.045± 0.109 (GeV/c2)2 <M2X - M2D>El>1.5 GeV = 0.293±0.012±0.033±0.048 (GeV/c2)4 hep-ex/0307081 Giuseppe Della Ricca – Semileptonic BRs and Moments

  31. Summary • Huge efforts/progress in this area !! • Large theoretical progress over the last decade (HQET & OPE) • Fully reconstructed B meson recoil tag, neutrino reconstruction • Many complementary observables • Inclusive studies yield crucial informations for Heavy Quark physics, even for exclusive decays Giuseppe Della Ricca – Semileptonic BRs and Moments

  32. Start of Backup Slides Giuseppe Della Ricca – Semileptonic BRs and Moments

  33. The BaBar detector ElectroMagnetic Calorimeter 6580 CsI(Tl) crystals 1.5 T solenoid Čerenkov Detector (DIRC) 144 quartz bars 11000 PMTs e+ (3.1 GeV) e- (9 GeV) Drift CHamber 40 stereo layers Silicon Vertex Tracker 5 layers, double sided strips Instrumented Flux Return iron/RPCs (muon/neutral hadrons) SVT:97% efficiency, 15 mm z hit resolution (inner layers,  tracks) SVT+DCH: (pT)/pT = 0.13 %  pT+ 0.45 % DIRC:K- separation 4.2 @ 3.0 GeV/c  >3.0 @ 4.0 GeV/c EMC:E/E = 2.3 %  E-1/4  1.9 % Giuseppe Della Ricca – Semileptonic BRs and Moments

  34. The BELLE detector Aerogel Cherenkov cnt. n=1.015~1.030 SC solenoid 1.5T 3.5 GeV e+ CsI(Tl) 16X0 TOF counter 8 GeV e- vtx sxy,z ~55mm@1GeV mom spt/pt=0.19pt (+) 0.34 % E sE/E~1.8% @E=1GeV PID: ACC+TOF+dE/dx(CDC) e~90%, h~6% up to 3GeV e-id: e>90%, h~0.3% (>1GeV) m-id: e>90%, h <2% (>1GeV) [e=efficiency, h=fake rate] Central Drift Chamber small cell +He/C2H5 m / KL detection 14/15 lyr. RPC+Fe Si vtx. detector 3 lyr. DSSD Giuseppe Della Ricca – Semileptonic BRs and Moments

  35. The CLEO detector Giuseppe Della Ricca – Semileptonic BRs and Moments

  36. The DELPHI detector Giuseppe Della Ricca – Semileptonic BRs and Moments

  37. The OPAL detector Giuseppe Della Ricca – Semileptonic BRs and Moments

  38. Inclusive bcl • rather than focusing on one hadronic final state, sum over all states and compare to quark level calculation • relies on assumption of quark-hadron duality • constrain theory parameters and test consistency Giuseppe Della Ricca – Semileptonic BRs and Moments

  39. Inclusive BR(B Xc l-)andtB Y(4S) BR(BXc l-) = (10.83 0.25) x10-2 tB = (1.598  0.01) ps GBXc l-= 0.446 (1 0.023 0.007)x10-10 MeV LEP BR(BX l-) = (10.590.22) x10-2 BR(BXu l-) = ( 0.170.05) x10-2 BR(BXc l-) = (10.420.26) x10-2 tb = (1.573  0.01) ps GBXc l-= 0.436 (1 0.022 0.014)x10-10 MeV GBXcl-= 0.441 (1 0.018) x10-10 MeV word average Giuseppe Della Ricca – Semileptonic BRs and Moments

  40. Reconstruction and cuts D*/D0 are reconstructed in the following modes: Giuseppe Della Ricca – Semileptonic BRs and Moments

  41. Moments of lepton energy spectrum and hadronic mass spectrum in Zbb events large momentum of b-hadrons (EB ~30 GeV) gives sensitivity to full lepton energy spectrum in B rest frame: measure first, second and third moment lepton spectrum in BXc l- background subtracted e+m B system reconstructed from lepton+neutrino+charm vertex lepton boosted in B rest frame DELPHI’03-28 p (GeV/c) Giuseppe Della Ricca – Semileptonic BRs and Moments

  42. Results for Mn <mnH>= pD mnD +pD* mnD* + (1-pD-pD* )<mnD**> moments of the hadronic mass measured M1= <m2H - m2D> = 0.647±0.046±0.093 (GeV/c2)2 M2= <(m2H - m2D)2> = 1.98±0.23±0.29 (GeV/c2)4 M2’=<(m2H- <m2H>)2> = 1.56±0.18±0.17 (GeV/c2)4 M3’=<(m2H- <m2H>)3> = 4.05±0.74±0.31 (GeV/c2)6 DELPHI’03-28 moments of the lepton energy spectrum unfolded spectrum <El*> = 1.383±0.012±0.009 GeV <(El*-<El*>)2> = 0.192±0.005±0.008 GeV2 <(El*-<El*>)3> =-0.029±0.005±0.006 GeV3 Giuseppe Della Ricca – Semileptonic BRs and Moments

  43. Electron Momentum [GeV/c] Lepton endpoint from the partial branching ratio with fu from CLEO (b®sg measurement) hep-ex/0207081 Giuseppe Della Ricca – Semileptonic BRs and Moments

  44. Hadronic moments - info Giuseppe Della Ricca – Semileptonic BRs and Moments

  45. End of Backup Slides Giuseppe Della Ricca – Semileptonic BRs and Moments

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