David Côté, Université de Montréal for the BABAR collaboration Semileptonic B decays, B mixing and magnitudes of CKM elements at BABAR David Côté, Université de Montréal for the BABAR collaboration DAΦNE 2004: Physics at meson factories

David Côté, Université de Montréal Outline 88106 BB ∫ Lon dt = 82 fb-1 Results presented today used less than half of the data we have now. |Vcb| |Vub| B0 – B0 mixing semileptonic B decays: BXc l  or BXu l  md, ... DAΦNE 2004 David Côté, Université de Montréal

Why studying semileptonic B decays and B0 - B0 mixing? To (over-)constrain the Standard Model and determine some of its fundamental parameters: mb, mc and CKM matrix elements To know more precisely parameters needed by other analyses (md, branching fractions, form factors,...) To learn about QCD and effective QCD DAΦNE 2004 David Côté, Université de Montréal

Inclusive |Vcb| measurement strategy f , f0 : heavy quark expansion (HQE) formulae* mb and mc : running quark masses (at  = 1 GeV) G, , LS, D : non-perturbative QCD parameters *Gambino & Uraltsev hep-ph/0401063 hep-ph/0403166 Problem: large uncertainties in mb, mc, ’s and ’s Solution: Measuring mb, mc, G, , LS, D, simultaneously to Br(BXc e ) and |Vcb| using HQE’s predictions of El and MXc moments. i=1..3 i=1..4 DAΦNE 2004 David Côté, Université de Montréal

electron energy moments Strategy: identify B  Xc e  decays with di-electron events Require typical B-B event topology, one high momentum etag and one opposite charge esig Subtract remaining backgrounds (mostly from data control samples) Corrections applied for Bremsstrahlung, e ID efficiency, etc. esig e- e+ Btag Bsig ν etag Data sample: ∫ L dt = 47.4 fb-1 400,000 events! Accepted by Phys. Rev. D hep-ex/0403030 esig energy spectrum used for moments measurement DAΦNE 2004 David Côté, Université de Montréal

David Côté, Université de Montréal hadronic mass moments Strategy: identify B  Xc l  decays on the recoil of fully reconstructed B’s Semileptonic side requirements : exactly one e or  with p* > 0.9 GeV/c Emiss, Pmiss consistent with a neutrino and net event charge  1 MXc reconstructed with a kinematic fit to all remaining particles Corrections for small MXc reconstruction bias computed from Monte Carlo Accepted by Phys. Rev. D hep-ex/0403031 BABAR El* > 0.9 GeV D* l p e+ Breco Brecoil Xc ν e- Clear sign of higher charm resonances DAΦNE 2004 David Côté, Université de Montréal

David Côté, Université de Montréal Fit results Accepted by Phys. Rev. Lett. hep-ex/0404017 MXc and El moments as a function of minimum El cut χ2 = 15 Ndof = 20 used in global fit not used in global fit Excellent agreement between lepton and hadron moments! Excellent agreement between data and HQE predictions! DAΦNE 2004 David Côté, Université de Montréal

|Vcb|: result and comparison 2% error on |Vcb|! |Vcb| Br(BX l ) DAΦNE 2004 David Côté, Université de Montréal

mb, mc: result and comparison kinetic mass scheme theory Conversion of mb and mc from kinetic mass to MS scheme by N. Uraltsev (hep-ph/9708372, hep-ph/0302262 , hep-ph/0304132) DAΦNE 2004 David Côté, Université de Montréal

David Côté, Université de Montréal Inclusive |Vub| Phys. Rev. Lett. 92:071802,2004 Strategy: same B  X l  selection as hadron mass moments (slide 6) BXu l  selection: kaon veto, low MX Measurement of for systematic errors cancellation Monte Carlo ∫ L dt = 82 fb-1 *Br(BXu l ) extracted from Ru using ref Phys.Rev.D67:031101,2003 Several avenues currently considered in order to reduce further the theoretical uncertainties. DAΦNE 2004 David Côté, Université de Montréal

David Côté, Université de Montréal Exclusive |Vub| Phys. Rev. Lett. 90:181801,2003 Strategy: untagged identification of B e  decays with “ reconstruction” Signal extracted by requiring: very high momentum electron E = Ebeam - E - El - Emiss compatible with zero M compatible with  mass Rather high theoretical uncertainties (~15%) Relatively high yield: 834  102 events (only electrons and 50.5 fb-1) exclusive analysis advantage MC GeV/c ∫L dt = 50.5 fb-1 Much more to be expected soon: larger dataset additional decay modes reduced theoretical uncertainties form factor(s) measurement new recoil techniques DAΦNE 2004 David Côté, Université de Montréal

David Côté, Université de Montréal « classic » B0 - B0 mixing (1) Phys.Rev.Lett.88:221802,2002 (2) Phys.Rev.Lett.88:221803,2002 (3) Phys.Rev.Lett.89:011802,2002 (4) Phys.Rev.D66:032003,2002 (5) Phys.Rev.D67:072002,2003 The B0 – B0 mixing technique is well-known and well-documented: Determination of vertex and flavor of the two B’s “t” between the two B’s estimated from distance between vertices “mixed” “unmixed” Results (23106 BB): (3) (averaged 1,2,5) DAΦNE 2004 David Côté, Université de Montréal

Generalized B0 - B0 mixing analysis B0 – B0 total decay-rate difference, CP violation in mixing and CPT violation were always neglected in mixing and CP measurements The validity of these assumptions was recently confirmed in a generalized B0 - B0 mixing analysis using 82 fb-1 ACP (ACP) is the amplitude for B0fCP (B0fCP) d/d : lifetime difference between BH and BL mass eigenstates (not “Bshort” and “Blong”) (): difference between flavor (mass) eigenstates z  (0,0): imply CPT violation |q/p|  1: imply Phys.Rev.Lett.92:181801,2004 hep-ex/0403002, submitted to PRD DAΦNE 2004 David Côté, Université de Montréal

David Côté, Université de Montréal Summary New BaBar precision measurement of |Vcb|, Br(BXc l ), mb, mc and 4 HQE parameters. 13% (18%) inclusive (exclusive) |Vub| measurement at BaBar using BXu l  decays (currently dominated by theory errors, but much progress to be expected soon). New measurement of d/d, |q/p| and z generalized mixing parameters validate the assumptions used for previous BaBar’s mixing and CP measurements. DAΦNE 2004 David Côté, Université de Montréal

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David Côté, Université de Montréal - plane DAΦNE 2004 David Côté, Université de Montréal

David Côté, Université de Montréal md,s vs Vtd,s  [known factors] needs latttice QCD calculations  [known factors] also needs latttice QCD calculations, but easier to compute. DAΦNE 2004 David Côté, Université de Montréal

electron energy moments Defining: We measured... the first moment: the central moments: n = 2,3 the partial branching fraction (0th moment): DAΦNE 2004 David Côté, Université de Montréal

David Côté, Université de Montréal HQE parameters We use calculations in kinetic mass scheme by Gambino and Uraltsev (HQE to order 1/mb3, as2 ) μπ2 - exp. value of kinetic energy of b quark inside B meson μG2 - exp. value of chromomagnetic moment operator ρD3 - exp. value of Darwin operator ρLS3 – exp. value of Spin-Orbit operator hep-ph/0401063 hep-ph/0403166 Ơ(1/mb2){ Ơ(1/mb3){ DAΦNE 2004 David Côté, Université de Montréal