Semileptonic B decays at BABAR

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1 at (University of Oregon) representing collaboration March 4, excluded area has <.5 CL η ε K V ub /V cb V ub V cb C K M f i t t e r LP 3 m d γ α sin β WA m s & m d ρ β ε K V cb Lepton energy moments Hadron mass moments OPE fit V ub B (B X u lν) B ± π lν, ρ lν, ωlν Search for physics beyond SM: τ lll

2 Measurements of V xb via B Xlν V cb, V ub b B q W + c, ū X e +, µ + ν e, ν µ Lepton energy spectrum b clν b ulν this talk V cb.4, B (B X c lν) 1% via incl. B (B X c lν) via incl. E l, M Xc spectra via excl. B (B D ( ) lν) Hadron mass spectrum this talk V ub.4, B (B X u lν).% via incl. lepton spectrum end point via incl. M Xu spectrum via excl. B (B ρ(π)lν)

3 Calculating V cb from inclusive B X c lν Operator Product Expansion (power series in α s and 1/m b ) calculates inclusive rate and moments of the E l, M X distributions: Theoretical uncertainty is 1.5% Rate : Γ clν = G F m5 b 19π 3 V cb (1 + A ew )A pert A nonpert = Vcb f OP E (a i ) up to α s and 1/m 3 b 6 parameters Moments: < X n > (E cut ) = (E l, M X ) (X X ) n dγ dx dx dγ dx dx = f OP E (a i ) El >E cut Cut on lepton energy Calculations are performed in different mass schemes PRD67(3)541 NPB665(3)367 3

4 Inclusive B X c lν: Electron Momentum Spectrum e B sig B tag e + e tag e sig Selection of di-electron events Statistics is large Backgrounds are sizable e ± identification is important Electrons / 5 MeV/c 6 4 a) b) Data e + e e ± e ± e from same B Fake electrons Dalitz Conversion Continuum * p [GeV/c] N + = (1 χ) N B Xeν + χ N B Xc Xeν + N + bgr N ±± = χ N B Xeν + (1 χ) N B Xc Xeν + N ±± bgr where χ is mixing parameter multiplied with fraction of neutral B mostly B Xeν mostly B X c Xeν 4

5 Electrons / 5 MeV/c N(B Xeν) Inclusive B X c lν: Electron Momentum Spectrum Υ(4S) rest frame Ldt = 47.4 fb 1 Br(B Xeν(γ)) Ecut >.6 GeV = (1.36 ±.6 stat ±.3 sys )% Submitted to PRL * p [GeV/c] Moments of B X c lν lepton spectrum as function of E cut lep BEl M de l B rest frame E cut [GeV] lep < M E l 1 >(GeV) E cut [GeV] < (E l < E l lep M >) >(GeV ) E cut [GeV] < (E lep l < E l M >) 3 >(GeV 3 ) E cut [GeV] Submitted to PRL corrected for efficiency and radiation. points are highly correlated. 5

6 Inclusive B X c lν: Hadron Mass Spectrum e B tag B sig e modes Fully reconstructed tag B No missing information Backgrounds are small Statistics is limited Signal side: B X c eν, B X c µν N events M X l sig 7114 events <M x > [GeV] Fit Υ(4S) B tag Xlν each event Calibrate M X on MC, check on D data Slope= Offset=.1+. GeV - D D D D ( ) π Slope= Offset=.6+. GeV <M x true > [GeV] Before and after calibration 6

7 Inclusive B X c lν: Hadron Mass Spectrum No dependence on the relative fractions and masses of various X c! Statistically independent of lepton energy moments measurement Moments of B X c lν hadron mass spectrum as function of E cut Ldt = 8 fb 1 Submitted to PRL (including all tables) <M X > [GeV] (a) (b) (c) (d) <M X > [GeV ] 4. <M X 3 > [GeV 3 ] 9 <M X 4 > [GeV 4 ] p* min [GeV] p* min [GeV] p* min [GeV] p* min [GeV] corrected for efficiency and radiation points are highly correlated. 7

8 Operator Product Expansion: kinetic scheme Taylor expansion V cb = B B Xc lν τ B [C + C i (a i a )] < X n > (E cut ) = C + C i (a i a ) leading order 1/m b 1/m 3 b Obtain parameters a i from the fit with no constraints: m b (1GeV) and m c (1GeV) - b- and c-quark masses µ π(1gev) - kinetic energy of the b-quark in the B-meson µ G(1GeV) - hyperfine splitting ρ 3 D(1GeV) - expectation value of Darwin operator ρ 3 LS(1GeV) - equivalent of the spin-orbital interaction in atoms B B Xc lν is extrapolation of < E l > to E cut = 8

9 Simultaneous fit of E l and M X moments.1 Calculations are taken from Gambino and Uraltsev hep-ph/4163. Simultaneous fit of electron energy moments and hadron mass. Only black points are used in the fit preliminary hadron mass moments M 1 X (GeV).6. M X (GeV ) (a) 4.1 (b) 8.4 (c) (d) M 3 X (GeV 3 ) M 4 X (GeV 4 ) M partial branching ratio M 1 (GeV) M (GeV ).4 (e) 1.4 (f) (g) -.3 (h) E cut (GeV) Bands correspond to the theoretical uncertainties M 3 (GeV 3 ) electron energy moments Fit quality: χ = 14.8 ndof 9

10 Fit E l and M X moments separately Constrained fit: χ = 1 ellipses Different theoretical accuracy for moments: < MX n > miss part of E cut-dependent perturbative corrections Experimental uncertainty for < MX n > is larger than for < El n > The variation of α s have very small impact on result The separate fit of moments (with constrained µ G and ρ3 LS ) are in very good agreement Vcb (1 3 ) preliminary All Moments Lepton Moments Hadron Moments m b (1GeV), GeV/c < M X > are fitted with < E l > 1

11 V cb determination preliminary V cb = (41.5 ±.45 exp ±.41 OP E ±.6 th ) 1 3 B B Xc lν = (1.6 ±.16 exp ±.6 OP E )% m b (1GeV) = (4.65 ±.5 exp ±.4 OP E )GeV (m b m c )(1GeV) = (3.43 ±. exp ±. OP E )GeV independent of scheme m b ( m b ) = (4.6 ±.5) GeV m c (1GeV) = (1. ±.9) GeV V cb (OPE) B B Xc lν (OPE fit) CLEO-1 (OPE) average HFAG CLEO- (OPE) (e tag) DELPHI (OPE) Belle (l tag) (E l ) CLEO (l tag) Belle (E l ) (breco) Belle (breco) HFAG (excl. D ) 1 11 % ARGUS Different OPE schemes 11

12 Inclusive B X u lν, low M X spectrum e B tag B sig e + l sig Fully reconstructed tag B. Suppress B X c lν on signal side. Get N B Xlν from m ES in each M X bin Fit M X to get N B Xu lν (Use wide bin for M X < 1.55GeV/c to minimize MC systematics) Measure B (B X u lν)/b (B Xlν) ) Events / (.5 MeV/c b) Events / Bin a) Data b u l ν b c l ν Other S B > [GeV/c ] m ES [GeV/c ] m X 1

13 3 /. '& %$ +* )(! -, 1 #" Inclusive measurement of V ub Accepted by PRL Ldt = 8 fb 1 B (B X u lν) B (B Xlν) = (.6 ±.5 stat ±.3 sys ±.36 th ) 1 B (B X u lν) = (.4 ±.7 stat ±.6 sys ±.39 th ) 1 3 B (b ulν). V ub =.445 (calculations from 1999) 1.55ps τ b (1 ±.56 th ) V ub = (4.6±.8 stat ±.7 sys ±.4 MC ±.6 th ) 1 3 V ub (m X ) Belle (m X q ) Belle (m X ) Belle (E l ) No cut on q is applied. Shape function uncertainty is not fully understood Events / Bin 1 5 b) Data b u l ν (E l ) CLEO (E l ) LEP Average OPAL DELPHI L3 ALEPH [GeV/c ] m X

14 Exclusive B X u lν channels Exclusive decays B X u lν are identified in the same sample ( Ldt = 8fb 1 ): B ± π lν B ± ρ lν B ± ωlν data events exclusive data events exclusive data events exclusive signal b->ulnu(oth) b->clnu other data 9 8 signal 14 signal 7 b->ulnu(oth) 1 b->ulnu(oth) 6 b->clnu 1 b->clnu 5 other other 8 4 data data m X (GeV/c ) m X (GeV/c ) m X (GeV/c ) preliminary B (B ± π lν) = (.78 ±.3 stat ±.13 sys )1 4 B (B ± ρ lν) = (.99 ±.37 stat ±.19 sys )1 4 B (B ± ωlν) = (. ±.9 stat ±.57 sys )1 4 ρ is π + π with.65 < m π + π <.95 GeV/c 14

15 4 Different subject: LFV τ lll decays e τ tag Search for signal of non-sm physics: Sensitive to SUSY, heavy sterile neutrino, etc data signal MC τ sig e +. - τ e - e + e τ µ e - e + - l 3 l l topology events E(lll) = E cms /, m(lll) = m τ Ldt = 9 fb 1 E (GeV) τ - µ - e + e τ - e + µ µ -.4 Decay N N bgd B τ e e + e ±.11 <. 1 7 τ µ + e e.37 ±.8 < τ µ e + e 1.6 ±.1 < τ e + µ µ.1 ±.7 < τ e µ + µ 1.39 ±.8 < τ µ µ + µ.31 ±.9 < LF V τ decays Olya Igonkina τ - e - µ µ M (GeV/c ) accepted by PRL τ - µ µ µ M (GeV/c ) 15

16 Summary New measurements of semileptonic B decays : moments of lepton energy up to 3rd order as function of E cut moments of hadron mass up to 4th order as function of E cut which are used in most precise OPE fit with no external parameters and constrains: V cb = (41.5 ±.45 exp ±.41 OP E ±.6 th ) 1 3 B B Xc lν = (1.6 ±.16 exp ±.6 OP E )% and precise determination of m b and m c Measurement of B (B X u lν)/b (B Xlν) on clean sample V ub = (4.6 ±.8 stat ±.7 sys ±.4 MC ±.6 th ) 1 3 New results in τ physics : upper limits on the fraction of lepton flavor violation decays B τ lll < at 9% CL More results soon!