1 / 45

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

jedidiah
Download Presentation

Semileptonic Branching Ratios and Moments

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. 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

More Related