1. 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

2. 2 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Motivations V ub,cb W u,cb l-l- l semileptonic decays are – –relatively simple theoretically at parton level – –accessible experimentally – –sensitive to quark couplings to W ± (i.e. CKM matrix elements |V ub | and |V cb |) – –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 |V xb | from the total rate

3. 3 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments 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

4. 4 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Framework B d mixing:  m d B s mixing:  m s /  m d sin2  b  ul : |V ub | D*l : |V cb |   measurements of |V ub | and |V cb | provide stringent tests of the unitarity triangle kaon decays: ε K

5. 5 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments 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 **0 l X) [Opal] inclusive measurements – –, in B  X c l [BaBar, Cleo, Delphi] – – BR(B  X u l ) [BaBar] – –  BR(B  X u l ) [Belle] Outline far too much interesting material to include in 20 min [apologies in advance] V cb or V ub my own selection of recent result

6. 6 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments HILEP  E M  (isospin-constrained average of   and  0 ) b  ce (HQET + Goity Roberts) signal (ISGW2) b  ue downfeed (ISGW2+DeFazio Neubert) crossfeed LOLEP EE MM  (B 0  - e + ) = 2  (B +  0 e + )  (B 0  - e + ) = 2  (B +  0 e + )  (B +  0 e + )=  (B +  e + ) BR(B 0   e - ) [1] HILEP: 2.3< E electron <2.7 GeV (large continuum backgrounds) LOLEP: 2.0< E electron <2.3 GeV (large b  ce backgrounds)

7. 7 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments BR(B 0   e - ) [2] combined result ( unweighted mean ): BR=(3.29  0.42  0.47  0.55 ) x 10 -4 PRL 90 (2003) 181801 theoretical error on the combined result: full spread seen between the different form-factors combined result: unweighted mean extrapolate partial branching fraction to entire lepton-energy spectrum using five different form-factor calculations

8. 8 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments BR(B  0 l,  “  0 ”l,  l ) 00 “0”“0”  very high purity but small statistics loose cuts: small model dependence BR(B  0 l ) = (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 “  0 ” : 0.65<m  <0.95 GeV/c 2 new CLEO results: see next talk !

9. 9 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments B  D * l  motivations B  D * l  represents 10% (5% e +5%  channel) of the total B 0 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 |V cb | D *±  D 0  ± D 0  K , K s , K  0, K   M [= M(D * )-M(D 0 )] used to fit signal and background components (except D ** ) e/  D0D0 ss B0B0  K constrained vertex fit on D 0 decay products, soft pion and lepton data control samples are used to estimate the background components (72 samples)

10. 10 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Background characterization: fit to  M [= M(D * )-M(D 0 )] fake D* fake lepton continuum uncorrelated from data control samples

11. 11 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Separation of D ** component once other backgrounds are estimated from the global fit, B 0(+)  D * Xl  events are separated using the angle between the B 0 and the D * l direction. can be written as: D ** shape different from the D * one fitted in each D 0 mode and e/  subsample electrons-K  mode D*l  D**l  Real D*, Fake  Uncorrelated D*  Correlated D*  Continuum D*  Fake D*  if B 0  D * l if B 0(+)  D * Xl pBpB p miss p p Y = p  + p lept  min  BY

12. 12 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Results for BR(B  D * l ) BR(B 0  D* - l + )= (4.69±0.02 stat.data ±0.02 stat.MC ±0.24 syst.data )% comparison with other results hep-ex/0308027

13. 13 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Orbitally excited D mesons (D ** ) D **0 are L=1 orbitally excited charm mesonsD **0 are L=1 orbitally excited charm mesons –narrow J q = 3/2, J p =1 +,2 + states (D 1 0, D 2 *0 ) –wide J q = 1/2, J p =0 +,1 + states (not visible with statistics) investigate the difference between measured inclusive and exclusive semileptonic branching ratiosinvestigate the difference between measured inclusive and exclusive semileptonic branching ratios reduce uncertainty in |V cb |reduce uncertainty in |V cb | test HQET predictionstest HQET predictions motivation

14. 14 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments identify high p lepton ( ,e) – –high efficiency and purity for p  > 3 GeV/c, p e > 2 GeV/c exclusively reconstruct D **0 D **0 D *+  **- D 0  + slow K -  + (  +  - ) background cuts to remove fake  **- (  from fragmentation) – –main background from decays plus fake  **- – –ANN (p, p T, d0/σ d0 ) to select  **- 3 mm Method

15. 15 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments D **0 – D *+ mass difference combine D 0 → K  and K3  channels to reduce uncertainty due to background unbinned ML fit to determine number of D 1 and D 2 * events (B.-W.  Gaussian) number of wrong sign and right sign background events fit simultaneously CERN-EP-2002-094

16. 16 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments B o & B + semileptonic decays accurate, separate BR sl for B o & B +, tagged by fully reconstructing one B BR(B +  Xl )/B(B 0  Xl )=1.14  0.04  0.01 BR sl (%)  sl (ns -1 ) BoBoBoBo 10.32  0.32  0.29 67.0  2.8 B+B+B+B+ 11.77  0.26  0.32 71.1  2.5 ½(B o + B + ) 11.19  0.20  0.31 69.0  1.9 Y(4S) 10.89  0.24 67.7  1.8  sl (B + )/  sl (B o )=1.063±0.038 preliminary

17. 17 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Semileptonic B decays average BR sl on Y(4S), use high momentum lepton to tag flavor of 1 st B LEP(most recent EW fit)=(10.59  0.22)%  10.76% at Y(4S) BR(B  Xe )= (10.89  0.08 stat  0.33 syst )% preliminary, EPS’03 272 CLEO

18. 18 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Parameters of HQE parameterization of decay rate in terms of Operator Product Expansion in HQET in powers of  s (m b )  0 and  /m B:     are non-perturbative parameters  1 : (-) kinetic energy of the motion of the b-quark  2 : chromo-magnetic coupling of b-quark spin to gluon (from B*-B mass difference, 2 =0.12GeV 2 )  = m B – m b + ( 1 - 3 2 )/2m B + … + additional parameters enter at higher orders (             ) use theoretical estimates –1/m B 3   pole mass expansion

19. 19 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments OPE parameter extraction E E first derivations of OPE parameters from spectral moments used the pole mass expansion and photon energy spectrum in B  X s  hadronic mass spectrum and lepton energy spectrum in B  X c l ElEl MX2MX2 PRL 87 (2001) 251807 PRL 87 (2001) 251808 PRD 67 (2001) 072001

20. 20 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments l -l - l D0D0 B  3mm  * D **  +  - K-K-  bb /  hadrons  22% E B  0.7 E beam  30 GeV D B Z  qq Moments of lepton energy spectrum and hadronic mass spectrum in Z  bb events B d 0  D ** l decays exclusively reconstructed in three channels: D **  D *+  -, D 0  +, D +  - signal:  * good secondary vertex reconstruction and signal/background separation first measurements of moments performed at LEP exploiting advantage of Z 0 kinematics

21. 21 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Hadronic mass spectrum in B  D ** l Hadronic mass spectrum in B  D ** l BR(B 0  D ** l )=(2.7  0.7  0.2) % D **  D 0  + D **  D +  - D **  D *+  -  M = M(D (*)  ) - M(D (*) ) distributions fitted including contributions of resonant (narrow, broad) and non resonant states, D * Xl floating DELPHI’03-28

22. 22 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments 1) pole mass expansions (Falk, Luke, Gambino) 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/m b 2  , 1, 2 ( 2  0.12 GeV 2 ), at order1/m b 3   1,  2,  1-4 two possible approaches: 2) running quark masses ( Bigi, Shifman, Uraltsev, Vainshtein )

23. 23 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments similar results with m b 1S - 1 formalism applied to CLEO and DELPHI data ( C.W.Bauer, Z.Ligeti, M.Luke, A.V.Manohar hep-ph/0210027 ) Pole mass scheme  (GeV 2   (GeV    (GeV 3  multi-parameter fit:  = 0.542 + 0.065 fit + 0.090 sys GeV   =-0.238 + 0.055 fit + 0.030 sys GeV 2   1 = 0.030 + 0.028 fit + 0.010 sys GeV 3    = 0.066 + 0.025 fit + 0.192 sys GeV 3 M 1 (M x ) M 2 (M x ) M 3 (M x ) M 1 (E l ) M 2 (E l ) M 3 (E l ) good consistency of all measurements (  2 /d.o.f.=0.4) results compatible with CLEO

24. 24 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Non-perturbative parameter extraction makes use of low scale running quark masses and does not rely on a 1/m c expansion first applied to fit DELPHI data – multi-parameter  2 fit to first three moments of lepton energy spectra and hadronic mass spectra (higher moments used to get sensitivity to 1/m b 3 parameters) – use expressions for non-truncated lepton spectra – simultaneous use of leptonic and hadronic moments in order to leave enough free parameters in the fit m b (  m c (  are independent parameters  and two operators only contribute to 1/m b 3 corrections :  D 3,  LS 3 Phys. Lett. B556 (2003) 41

25. 25 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments  D 3 (GeV 3  Kinetic mass scheme m b,kin (1GeV)= 4.570 +0.082 fit +0.010 sys GeV m c,kin (1GeV)= 1.133 +0.134 fit +0.030 sys GeV   2 (1GeV) = 0.382 +0.070 fit +0.030 sys GeV 2  D 3 (1GeV) = 0.089 +0.039 fit +0.010 sys GeV 3   2 (GeV 2  m b (GeV  good consistency of all measurements (  2 /d.o.f.=0.9) within present accuracy no need to introduce higher order terms to establish agreement with data M 1 (M x ) M 2 (M x ) M 3 (M x ) M 1 (E l ) M 2 (E l ) M 3 (E l ) input constraints:  G 2 = 0.35 +0.05 GeV 2  LS 3 = -0.15 +0.15 GeV 3 m c = 1.05  0.30 GeV m b = 4.57  0.10 GeV equivalent to that derived from E  in B  X s  4-parameter fit

26. 26 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments parameters extracted from lepton spectra are in agreement with those extracted from M X 2 and E  using ratios of truncated lepton spectra (Gremm et al. PRL77 20 ’96) Generalized energy moments 1  theoretical ellipse  = 0.39±0.03 stat ±0.06 sys ±0.12 th GeV 1 =  0.25±0.02 stat ±0.05 sys ±0.14 th GeV 2 hep-ex/0212051

27. 27 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Hadronic mass moments [1] TRUE non-res D** D* D measured M X differs from true M X for each interval in M X, full detector simulation gives and calibration curves applied to data: no model dependence ! p min * dependence study ~ ~ ~ p min *

28. 28 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Hadronic mass moments [2] fit OPE for to data and extract the two leading HQE parameters  and 1 (MS scheme)  all correlations taken into account CLEO b  s  p min * OPE prediction using CLEO data only and from b  s  OPE fit all hadron mass moments are consistent (overlap from bands and BABAR ellipse) but  2 =1 contour does not overlap with band from CLEO b  s  _

29. 29 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Hadronic mass moments [3] extraction of m b 1s, and 1 1s from a fit to the HQE in the 1s mass scheme (O(1/m b 3 ) parameters are fixed in the fit)  2 =1 contour of hadron moments and lepton moments do not overlap indication for large O(1/m b 3 ) corrections, duality violation, or maybe even more …? hep-ex/0307046

30. 30 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Hadronic mass moments hep-ex/0307081 El>1.0 GeV = 0.456±0.014±0.045± 0.109 (GeV/c 2 ) 2 El>1.5 GeV = 0.293±0.012±0.033±0.048 (GeV/c 2 ) 4 the neutrino 4-vector is inferred using the detector hermeticity

31. 31 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments 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

32. 32 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Start of Backup Slides

33. 33 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments The BaBar detector Čerenkov Detector (DIRC) 144 quartz bars 11000 PMTs 1.5 T solenoid ElectroMagnetic Calorimeter 6580 CsI(Tl) crystals Drift CHamber 40 stereo layers Instrumented Flux Return iron/RPCs (muon/neutral hadrons) Silicon Vertex Tracker 5 layers, double sided strips e + (3.1 GeV) e - (9 GeV) SVT: 97% efficiency, 15  m z hit resolution (inner layers,  tracks) SVT+DCH:  (p T )/p T = 0.13 %  p T + 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 %

34. 34 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments  / K L detection 14/15 lyr. RPC+Fe Central Drift Chamber small cell +He/C 2 H 5 CsI(Tl) 16X 0 Aerogel Cherenkov cnt. n=1.015~1.030 Si vtx. detector 3 lyr. DSSD SC solenoid 1.5T 3.5 GeV e  8 GeV e  vtx  xy,z  m  @1GeV mom  pt /p t =0.19p t (+) 0.34 % E  E /E~1.8% @E=1GeV PID: ACC+TOF+dE/dx(CDC)  ~90%,  ~6% up to 3GeV e-id:  >90%,  ~0.3% (>1GeV)  -id:  >90%,  1GeV)  =efficiency,  =fake rate] The BELLE detector TOF counter

35. 35 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments The CLEO detector

36. 36 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments The DELPHI detector

37. 37 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments The OPAL detector

38. 38 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Inclusive b  cl 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

39. 39 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments  B  X c l  = 0.441 (1  0.018) x10  MeV word average Inclusive BR(B  X c l  ) and  B Y(4S) BR(B  X c l  ) = (10.83  0.25) x10  2  B = (1.598  0.01) ps  B  Xc l  = 0.446 (1  0.023  0.007)x10  MeV LEP BR(B  X l  ) = (10.59  0.22) x10  2 BR(B  X u l  ) = ( 0.17  0.05) x10  2 BR(B  X c l  ) = (10.42  0.26) x10  2  b = (1.573  0.01) ps  B  Xc l  = 0.436 (1  0.022  0.014)x10  MeV

40. 40 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Reconstruction and cuts D * /D 0 are reconstructed in the following modes: decay modeBR (%) D *±  D 0  ± 67.7 ± 0.5 D 0  K  3.80 ± 0.09 D 0  K s  2.96 ± 0.18 D 0  K  0 13.1 ± 0.9 D 0  K  7.46 ± 0.31

41. 41 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Moments of lepton energy spectrum and hadronic mass spectrum in Z  bb events background subtracted B system reconstructed from lepton+neutrino+charm vertex lepton boosted in B rest frame e+  lepton spectrum in B  X c l  large momentum of b-hadrons (E B ~30 GeV) gives sensitivity to full lepton energy spectrum in B rest frame: measure first, second and third moment p (GeV/c) DELPHI’03-28

42. 42 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Results for M n Results for M n DELPHI’03-28 moments of the lepton energy spectrum M 1 = = 0.647±0.046±0.093 (GeV/c 2 ) 2 M 2 = = 1.98±0.23±0.29 (GeV/c 2 ) 4 M 2 ’= ) 2 > = 1.56±0.18±0.17 (GeV/c 2 ) 4 M 3 ’= ) 3 > = 4.05±0.74±0.31 (GeV/c 2 ) 6 = 1.383±0.012±0.009 GeV ) 2 > = 0.192±0.005±0.008 GeV 2 ) 3 > =-0.029±0.005±0.006 GeV 3 = p D m n D +p D* m n D* + (1-p D -p D* ) measured moments of the hadronic mass unfolded spectrum

43. 43 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Lepton endpoint from the partial branching ratio with f u from CLEO (b  s  measurement) Electron Momentum [GeV/c] hep-ex/0207081

44. 44 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments Hadronic moments - info

45. 45 BEAUTY’03 – October 14-18, 2003 Giuseppe Della Ricca – Semileptonic BRs and Moments End of Backup Slides