-
B. Aubert,
D. Boutigny,
J.-M. Gaillard,
A. Hicheur,
Y. Karyotakis,
J. P. Lees,
P. Robbe,
V. Tisserand,
A. Palano,
A. Pompili, [......],
F. Di Lodovico,
Y. Pan,
R. Prepost,
I. J. Scott,
S. J. Sekula,
J. H. von Wimmersperg-Toeller,
S. L. Wu,
Z. Yu,
T. M. B. Kordich,
H. Neal
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of time-dependent CP-violating asymmetries in neutral B meson decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the Stanford Linear Accelerator Center. The data sample consists of 29.7 fb-1 recorded at the Υ(4S) resonance and 3.9 fb-1 off resonance. One of the neutral B mesons, which are produced in pairs at the Υ(4S), is fully reconstructed in the CP decay modes J/ψKS0, ψ(2S)KS0, χc1KS0, J/ψK*0 (K*0→KS0π0) and J/ψKL0, or in flavor-eigenstate modes involving D(*)π/ρ/a1 and J/ψK*0 (K*0→K+π-). The flavor of the other neutral B meson is tagged at the time of its decay, mainly with the charge of identified leptons and kaons. A neural network tagging algorithm is used to recover events without a clear lepton or kaon tag. The proper time elapsed between the decays is determined by measuring the distance between the decay vertices. Wrong-tag probabilities, the time-difference resolution function, and the B0-B0 oscillation frequency Δmd are measured with a sample of about 6350 fully-reconstructed B0 decays in hadronic flavor-eigenstate modes. A maximum-likelihood fit to this flavor eigenstate sample finds Δmd=0.516±0.016(stat)±0.010(syst)ps-1. The value of the asymmetry amplitude sin2β is determined from a simultaneous maximum-likelihood fit to the time-difference distribution of the flavor-eigenstate sample and about 642 tagged B0 decays in the CP-eigenstate modes. We find sin2β=0.59±0.14(stat)±0.05(syst), demonstrating that CP violation exists in the neutral B meson system. We also determine the value of the CP violation parameter |λ|=0.93±0.09(stat)±0.03(syst), which is consistent with the expectation of |λ|=1 for no direct CP violation.
Physical Review D 02/2013; 66(3). · 4.56 Impact Factor
-
B Aubert,
D Boutigny,
JM Gaillard,
A Hicheur,
Y Karyotakis,
JP Lees,
P Robbe,
V Tisserand,
A Palano,
GP Chen, [......],
Y Pan,
R Prepost,
IJ Scott,
SJ Sekula,
JH von Wimmerspeig-Toeller,
SL Wu,
Z Yu,
H Zobernig,
TMB Kordich,
H Neal
[show abstract]
[hide abstract]
ABSTRACT: We report branching fraction measurements for exclusive decays of charged and neutral B mesons into two-body final states containing a charmonium meson. We use a sample of 22.72±0.36 million BB̅ events collected between October 1999 and October 2000 with the BABAR detector at the PEP-II storage rings at the Stanford Linear Accelerator Center. The charmonium mesons considered here are J/ψ, ψ(2S), and χc1, and the light meson in the decay is either a K, K*, or π0.
Physical Review D 02/2013; 65. · 4.56 Impact Factor
-
B Aubert,
D Boutigny,
JM Gaillard,
A Hicheur,
Y Karyotakis,
JP Lees,
P Robbe,
V Tisserand,
A Palano,
GP Chen, [......],
Y Pan,
R Prepost,
IJ Scott,
SJ Sekula,
JH von Wimmersperg-Toeller,
SL Wu,
Z Yu,
H Zobernig,
TMB Kordich,
H Neal
[show abstract]
[hide abstract]
ABSTRACT: The B0 and B+ meson lifetimes have been measured in e+e- annihilation data collected in 1999 and 2000 with the BABAR detector at center-of-mass energies near the ϒ(4S) resonance. Events are selected in which one B meson is fully reconstructed in a hadronic final state while the second B meson is reconstructed inclusively. A combined fit to the B0 and the B+ decay time difference distributions yields τB0 = 1.546±0.032(stat)±0.022(syst) ps, τB+ = 1.673±0.032(stat)±0.023(syst) ps, and τB+/τB0 = 1.082±0.026(stat)±0.012(syst).
Physical Review Letters 02/2013; 87(20). · 7.37 Impact Factor
-
BABAR Collaboration,
B Aubert,
D Boutigny,
JM Gaillard,
A Hicheur,
Y Karyotakis,
JP Lees,
P Robbe,
V Tisserand,
A Palano, [......],
R Liu,
Y Pan,
R Prepost,
IJ Scott,
SJ Sekula,
JH von Wimmersperg-Toeller,
SL Wu,
Z Yu,
TMB Kordich,
H Neal
[show abstract]
[hide abstract]
ABSTRACT: New measurements of Ds+ and Ds*+ meson production rates from B decays and from qq̅ continuum events near the Υ(4S) resonance are presented. Using 20.8 fb-1 of data on the Υ(4S) resonance and 2.6 fb-1 off-resonance, we find the inclusive branching fractions B(B⃗Ds+X)=(10.93±0.19±0.58±2.73)% and B(B⃗Ds*+X)=(7.9±0.8±0.7±2.0)%, where the first error is statistical, the second is systematic, and the third is due to the Ds+→φπ+ branching fraction uncertainty. The production cross sections σ(e+e-→Ds+X)×B(Ds+→φπ+)=7.55±0.20±0.34pb and σ(e+e-→Ds*±X)×B(Ds+→φπ+)=5.8±0.7±0.5pb are measured at center-of-mass energies about 40 MeV below the Υ(4S) mass. The branching fractions ΣB(B⃗Ds(*)+D(*))=(5.07±0.14±0.30±1.27)% and ΣB(B⃗Ds*+D(*))=(4.1±0.2±0.4±1.0)% are determined from the Ds(*)+ momentum spectra. The mass difference m(Ds+)-m(D+)=98.4±0.1±0.3MeV/c2 is also measured.
Physical Review D 02/2013; 65(9). · 4.56 Impact Factor
-
BABAR Collaboration,
B Aubert,
D Boutigny,
JM Gaillard,
A Hicheur,
Y Karyotakis,
JP Lees,
P Robbe,
V Tisserand,
A Palano, [......],
F Di Lodovico,
Y Pan,
R Prepost,
IJ Scott,
SJ Sekula,
JH von Wimmersperg-Toeller,
SL Wu,
Z Yu,
TMB Kordich,
H Neal
[show abstract]
[hide abstract]
ABSTRACT: Flavor oscillations of neutral B mesons have been studied in e+e- annihilation data collected with the BABAR detector at center-of-mass energies near the ϒ(4S) resonance. The data sample used for this purpose consists of events in which one B0 meson is reconstructed in a hadronic decay mode, while the flavor of the recoiling B0 is determined with a tagging algorithm that exploits the correlation between the flavor of the heavy quark and the charges of its decay products. From the time development of the observed mixed and unmixed final states, we determine the B0-B̅ 0 oscillation frequency Δmd to be 0.516±0.016(stat)±0.010(syst) ps-1.
Physical Review Letters 02/2013; 88(22). · 7.37 Impact Factor
-
BABAR Collaboration,
B Aubert,
D Boutigny,
JM Gaillard,
A Hicheur,
Y Karyotakis,
JP Lees,
P Robbe,
V Tisserand,
A Palano, [......],
F Di Lodovico,
Y Pan,
R Prepost,
IJ Scott,
SJ Sekula,
JH von Wimmersperg-Toeller,
S L Wu,
Z Yu,
TMB Kordich,
H Neal
[show abstract]
[hide abstract]
ABSTRACT: We search for direct CP violation in charmless hadronic B decays observed in a sample of about 22.7 million BB̅ pairs collected with the BABAR detector at the SLAC PEP-II asymmetric-energy e+e- collider. We measure the following charge asymmetries: ACP(B±→η′K±)=-0.11±0.11±0.02, ACP(B±→ωπ±)=-0.01 - 0.31 + 0.29±0.03, ACP(B±→φK±)=-0.05±0.20±0.03, ACP(B±→φK*±)=-0.43 - 0.30 + 0.36±0.06, and ACP(B0→φK*0)=0.00±0.27±0.03.
Physical Review D 02/2013; 65(5):051101. · 4.56 Impact Factor
-
BABAR Collaboration,
B Aubert,
D Boutigny,
JM Gaillard,
A Hicheur,
Y Karyotakis,
JP Lees,
P Robbe,
V Tisserand,
A Palano, [......],
F Di Lodovico,
Y Pan,
R Prepost,
IJ Scott,
SJ Sekula,
JH von Wimmersperg-Toeller,
SL Wu,
Z Yu,
TMB Kordich,
H Neal
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of time-dependent CP-violating asymmetries in neutral B meson decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the Stanford Linear Accelerator Center. The data sample consists of 29.7 fb-1 recorded at the Υ(4S) resonance and 3.9 fb-1 off resonance. One of the neutral B mesons, which are produced in pairs at the Υ(4S), is fully reconstructed in the CP decay modes J/ψKS0, ψ(2S)KS0, χc1KS0, J/ψK*0 (K*0→KS0π0) and J/ψKL0, or in flavor-eigenstate modes involving D(*)π/ρ/a1 and J/ψK*0 (K*0→K+π-). The flavor of the other neutral B meson is tagged at the time of its decay, mainly with the charge of identified leptons and kaons. A neural network tagging algorithm is used to recover events without a clear lepton or kaon tag. The proper time elapsed between the decays is determined by measuring the distance between the decay vertices. Wrong-tag probabilities, the time-difference resolution function, and the B0-B0 oscillation frequency Δmd are measured with a sample of about 6350 fully-reconstructed B0 decays in hadronic flavor-eigenstate modes. A maximum-likelihood fit to this flavor eigenstate sample finds Δmd=0.516±0.016(stat)±0.010(syst)ps-1. The value of the asymmetry amplitude sin2β is determined from a simultaneous maximum-likelihood fit to the time-difference distribution of the flavor-eigenstate sample and about 642 tagged B0 decays in the CP-eigenstate modes. We find sin2β=0.59±0.14(stat)±0.05(syst), demonstrating that CP violation exists in the neutral B meson system. We also determine the value of the CP violation parameter |λ|=0.93±0.09(stat)±0.03(syst), which is consistent with the expectation of |λ|=1 for no direct CP violation.
Physical Review D 02/2013; 66(3). · 4.56 Impact Factor
-
The Babar Collaboration,
J. P. Lees,
V. Poireau,
V. Tisserand,
E. Grauges,
A. Palano,
G. Eigen,
B. Stugu,
D. N. Brown,
L. T. Kerth, [......],
R. J. Sobie,
N. Tasneem,
T. J. Gershon,
P. F. Harrison,
T. E. Latham,
H. R. Band,
S. Dasu,
Y. Pan,
R. Prepost,
S. L. Wu
[show abstract]
[hide abstract]
ABSTRACT: We study the decay
$\bar{B}^{0}\rightarrow\Lambda_{c}^{+}\bar{p}\pi^{+}\pi^{-}$, reconstructing
the \Lambda_{c}^{+} baryon in the $p K^{-}\pi^{+}$ mode, using a data sample of
$467\times 10^{6}$ $B\bar{B}$ pairs collected with the BaBar detector at the
PEP-2 storage rings at SLAC. We measure branching fractions for decays with
intermediate $\Sigma_{c}$ baryons to be ${\cal
B}[\bar{B}^{0}\rightarrow\Sigma_{c}(2455)^{++}\bar{p}\pi^{-}]=(21.3 \pm 1.0 \pm
1.0 \pm 5.5) \times 10^{-5}$, ${\cal
B}[\bar{B}^{0}\rightarrow\Sigma_{c}(2520)^{++}\bar{p}\pi^{-}]=(11.5\pm 1.0 \pm
0.5 \pm 3.0)\times 10^{-5}$, ${\cal
B}[\bar{B}^{0}\rightarrow\Sigma_{c}(2455)^{0}\bar{p}\pi^{+}]=(9.1 \pm 0.7 \pm
0.4 \pm 2.4)\times10^{-5}$, and ${\cal
B}[\bar{B}^{0}\rightarrow\Sigma_{c}(2520)^{0}\bar{p}\pi^{+}]= (2.2 \pm 0.7 \pm
0.1\pm 0.6) \times 10^{-5}$, where the uncertainties are statistical,
systematic, and due to the uncertainty on the
$\Lambda_{c}^{+}\rightarrow\proton\Km\pi^{+}$ branching fraction, respectively.
For decays without $\Sigma_{c}(2455)$ or $\Sigma_{c}(2520)$ resonances, we
measure ${\cal
B}[\bar{B}^{0}\rightarrow\Lambda_{c}^{+}\bar{p}\pi^{+}\pi^{-}]_{\mathrm{non-\Sigma_{c}}}=(79
\pm 4 \pm 4 \pm 20)\times10^{-5}$. The total branching fraction is determined
to be ${\cal
B}[\bar{B}^{0}\rightarrow\Lambda_{c}^{+}\bar{p}\pi^{+}\pi^{-}]_{\mathrm{total}}=(123
\pm 5 \pm 7 \pm 32)\times10^{-5}$. We examine multibody mass combinations in
the resonant three-particle $\Sigma_{c}\bar{p}\pi$ final states and in the
four-particle $\Lambda_{c}^{+}\bar{p}\pi^{+}\pi^{-}$ final state, and observe
different characteristics for the $\bar{p}\pi$ combination in neutral versus
doubly-charged $\Sigma_{c}$ decays.
02/2013;
-
A. Aktas,
V. Andreev,
T. Anthonis,
B. Antunovic,
S. Aplin,
A. Asmone,
A. Astvatsatourov,
A. Babaev,
S. Backovic,
A. Baghdasaryan, [......],
T. Kluge,
G. Knies,
A. Knutsson,
V. Korbel,
P. Kostka,
K. Krastev,
J. Kretzschmar,
A. Kropivnitskaya,
K. Krüger,
M.P.J. Landon
-
A. Aktas,
V Andreev,
T Anthonis,
B. Antunovic,
S. Aplin,
A. Asmone,
A. Astvatsatourov,
A Babaev,
S. Backovic,
A. Baghdasaryan, [......],
T. Kluge,
G Knies,
A. Knutsson,
V Korbel,
P Kostka,
K. Krastev,
J. Kretzschmar,
A. Kropivnitskaya,
K Krüger,
M P J Landon
-
BaBar Collaboration,
J. P. Lees,
V. Poireau,
V. Tisserand,
J. Garra Tico,
E. Grauges,
A. Palano,
G. Eigen,
B. Stugu,
D. N. Brown, [......],
R. J. Sobie,
N. Tasneem,
T. J. Gershon,
P. F. Harrison,
T. E. Latham,
H. R. Band,
S. Dasu,
Y. Pan,
R. Prepost,
S. L. Wu
[show abstract]
[hide abstract]
ABSTRACT: We report on a search for direct CP asymmetry in the singly
Cabibbo-suppressed decay D+- --> K+ K- pi+- using a data sample of 476 fb-1
accumulated with the BaBar detector running at and just below the Y(4S)
resonance. The CP-violating decay rate asymmetry A_CP is determined to be (0.35
+- 0.30 +- 0.15)%. Model-dependent and model-independent Dalitz plot analysis
techniques are used to search for CP-violating asymmetries in the various
intermediate states.
12/2012;
-
J P Lees,
V Poireau,
V Tisserand,
J Garra Tico,
E Grauges,
A Palano,
G Eigen,
B Stugu,
D N Brown,
L T Kerth, [......],
R J Sobie,
N Tasneem,
T J Gershon,
P F Harrison,
T E Latham,
H R Band,
S Dasu,
Y Pan,
R Prepost,
S L Wu
[show abstract]
[hide abstract]
ABSTRACT: Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavor states (B^{0} or B[over ¯]^{0}), and J/ψK_{L}^{0} or cc[over ¯]K_{S}^{0} final states (referred to as B_{+} or B_{-}), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, B[over ¯]^{0}→B_{-} and B_{-}→B[over ¯]^{0}, as a function of the time difference between the two B decays. Using 468×10^{6} BB[over ¯] pairs produced in Υ(4S) decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding ΔS_{T}^{+}=-1.37±0.14(stat)±0.06(syst) and ΔS_{T}^{-}=1.17±0.18(stat)±0.11(syst). These nonzero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.
Physical Review Letters 11/2012; 109(21):211801. · 7.37 Impact Factor
-
J P Lees,
V Poireau,
V Tisserand,
J Garra Tico,
E Grauges,
A Palano,
G Eigen,
B Stugu,
D N Brown,
L T Kerth, [......],
N Tasneem,
T J Gershon,
P F Harrison,
T E Latham,
E M T Puccio,
H R Band,
S Dasu,
Y Pan,
R Prepost,
S L Wu
[show abstract]
[hide abstract]
ABSTRACT: The photon spectrum in the inclusive electromagnetic radiative decays of the B meson, B→X_{s}γ plus B→X_{d}γ, is studied using a data sample of (382.8±4.2)×10^{6}Υ(4S)→BB[over ¯] decays collected by the BABAR experiment at SLAC. The spectrum is used to extract the branching fraction B(B→X_{s}γ)=(3.21±0.33)×10^{-4} for E_{γ}>1.8 GeV and the direct CP asymmetry A_{CP}(B→X_{s+d}γ)=0.057±0.063. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the B meson rest frame.
Physical Review Letters 11/2012; 109(19):191801. · 7.37 Impact Factor
-
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
C. Alexa,
V. Andreev,
S. Antonelli,
P. Antonioli,
A. Antonov, [......],
W. Zeuner,
Z. Zhang,
B. O. Zhautykov,
N. Zhmak,
A. Zichichi,
R. Žlebčík,
H. Zohrabyan,
Z. Zolkapli,
F. Zomer,
D. S. Zotkin
[show abstract]
[hide abstract]
ABSTRACT: Measurements of open charm production cross sections in deep-inelastic ep
scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced
cross sections sigma_red^{c\bar{c}} for charm production are obtained in the
kinematic range of photon virtuality 2.5<Q2<2000 GeV2 and Bjorken scaling
variable 0.00003<x<0.05. The combination method accounts for the correlations
of the systematic uncertainties among the different data sets. The combined
charm data together with the combined inclusive deep-inelastic scattering cross
sections from HERA are used as input for a detailed NLO QCD analysis to study
the influence of different heavy flavour schemes on the parton distribution
functions. The optimal values of the charm mass as a parameter in these
different schemes are obtained. The implications on the NLO predictions for
W^{\pm} and Z production cross sections at the LHC are investigated. Using the
fixed flavour number scheme, the running mass of the charm quark is determined.
11/2012;
-
J. P. Lees,
V. Poireau,
V. Tisserand,
J. Garra Tico,
E. Grauges,
A. Palano,
G. Eigen,
B. Stugu,
D. N. Brown,
L. T. Kerth, [......],
N. Tasneem,
T. J. Gershon,
P. F. Harrison,
T. E. Latham,
E. M. T. Puccio,
H. R. Band,
S. Dasu,
Y. Pan,
R. Prepost,
S. L. Wu
[show abstract]
[hide abstract]
ABSTRACT: We use 429 fb-1 of e+e- collision data collected at the Υ(4S) resonance with the BABAR detector to measure the radiative transition rate of b→sγ with a sum of 38 exclusive final states. The inclusive branching fraction with a minimum photon energy of 1.9 GeV is found to be B(B̅ →Xsγ)=(3.29±0.19±0.48)×10-4 where the first uncertainty is statistical and the second is systematic. We also measure the first and second moments of the photon energy spectrum and extract the best-fit values for the heavy-quark parameters, mb and μπ2, in the kinetic and shape function models.
Phys. Rev. D. 09/2012; 86(5).
-
J P Lees,
V Poireau,
V Tisserand,
J Garra Tico,
E Grauges,
A Palano,
G Eigen,
B Stugu,
D N Brown,
L T Kerth, [......],
R J Sobie,
N Tasneem,
T J Gershon,
P F Harrison,
T E Latham,
H R Band,
S Dasu,
Y Pan,
R Prepost,
S L Wu
[show abstract]
[hide abstract]
ABSTRACT: Based on the full BABAR data sample, we report improved measurements of the ratios R(D^{(*)})=B(B[over ¯]→D^{(*)}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]→D^{(*)}ℓ_{ℓ}^{-}ν[over ¯]_{ℓ}), where ℓ is either e or μ. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D)=0.440±0.058±0.042 and R(D^{*})=0.332±0.024±0.018, which exceed the standard model expectations by 2.0σ and 2.7σ, respectively. Taken together, our results disagree with these expectations at the 3.4σ level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model.
Physical Review Letters 09/2012; 109(10):101802. · 7.37 Impact Factor
-
J. P. Lees,
V. Poireau,
V. Tisserand,
J. Garra Tico,
E. Grauges,
A. Palano,
G. Eigen,
B. Stugu,
D. N. Brown,
L. T. Kerth, [......],
N. Tasneem,
T. J. Gershon,
P. F. Harrison,
T. E. Latham,
E. M. T. Puccio,
H. R. Band,
S. Dasu,
Y. Pan,
R. Prepost,
S. L. Wu
[show abstract]
[hide abstract]
ABSTRACT: A precise measurement of the cross section of the process e+e-→π+π-(γ) from threshold to an energy of 3 GeV is obtained with the initial-state radiation (ISR) method using 232 fb-1 of data collected with the BABAR detector at e+e- center-of-mass energies near 10.6 GeV. The ISR luminosity is determined from a study of the leptonic process e+e-→μ+μ-(γ)γISR, which is found to agree with the next-to-leading-order QED prediction to within 1.1%. The cross section for the process e+e-→π+π-(γ) is obtained with a systematic uncertainty of 0.5% in the dominant ρ resonance region. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the measured ππ cross section from threshold to 1.8 GeV is (514.1±2.2(stat)±3.1(syst))×10-10.
Phys. Rev. D. 08/2012; 86(3).
-
J. P. Lees,
V. Poireau,
V. Tisserand,
J. Garra Tico,
E. Grauges,
A. Palano,
G. Eigen,
B. Stugu,
D. N. Brown,
L. T. Kerth, [......],
N. Tasneem,
T. J. Gershon,
P. F. Harrison,
T. E. Latham,
E. M. T. Puccio,
H. R. Band,
S. Dasu,
Y. Pan,
R. Prepost,
S. L. Wu
[show abstract]
[hide abstract]
ABSTRACT: In a sample of 471×106 BB̅ events collected with the BABAR detector at the PEP-II e+e- collider we study the rare decays B→K(*)ℓ+ℓ-, where ℓ+ℓ- is either e+e- or μ+μ-. We report results on partial branching fractions and isospin asymmetries in seven bins of dilepton mass-squared. We further present CP and lepton-flavor asymmetries for dilepton masses below and above the J/ψ resonance. We find no evidence for CP or lepton-flavor violation. The partial branching fractions and isospin asymmetries are consistent with the Standard Model predictions and with results from other experiments.
Phys. Rev. D. 08/2012; 86(3).
-
J. P. Lees,
V. Poireau,
V. Tisserand,
J. Garra Tico,
E. Grauges,
M. Martinelli,
D. A. Milanes,
A. Palano,
M. Pappagallo,
G. Eigen, [......],
N. Tasneem,
T. J. Gershon,
P. F. Harrison,
T. E. Latham,
E. M. T. Puccio,
H. R. Band,
S. Dasu,
Y. Pan,
R. Prepost,
S. L. Wu
[show abstract]
[hide abstract]
ABSTRACT: We report measurements of partial branching fractions for inclusive charmless semileptonic B decays B̅ →Xuℓν̅ and the determination of the Cabibbo–Kobayashi–Maskawa (CKM) matrix element |Vub|. The analysis is based on a sample of 467×106 Υ(4S)→BB̅ decays recorded with the BABAR detector at the PEP-II e+e- storage rings. We select events in which the decay of one of the B mesons is fully reconstructed and an electron or a muon signals the semileptonic decay of the other B meson. We measure partial branching fractions ΔB in several restricted regions of phase space and determine the CKM element |Vub| based on different QCD predictions. For decays with a charged lepton momentum pℓ*>1.0 GeV in the B meson rest frame, we obtain ΔB=(1.80±0.13stat±0.15sys±0.02theo)×10-3 from a fit to the two-dimensional MX-q2 distribution. Here, MX refers to the invariant mass of the final state hadron X and q2 is the invariant mass squared of the charged lepton and neutrino. From this measurement we extract |Vub|=(4.33±0.24exp±0.15theo)×10-3 as the arithmetic average of four results obtained from four different QCD predictions of the partial rate. We separately determine partial branching fractions for B̅ 0 and B- decays and derive a limit on the isospin breaking in B̅ →Xuℓν̅ decays.
Phys. Rev. D. 08/2012; 86(3).
-
BABAR Collaboration,
J. P. Lees,
V. Poireau,
V. Tisserand,
J. Garra Tico,
E. Grauges,
A. Palano,
G. Eigen,
B. Stugu,
D. N. Brown, [......],
R. J. Sobie,
N. Tasneem,
T. J. Gershon,
P. F. Harrison,
T. E. Latham,
H. R. Band,
S. Dasu,
Y. Pan,
R. Prepost,
S. L. Wu
[show abstract]
[hide abstract]
ABSTRACT: We report the results of a study of the exclusive charmless semileptonic
decays, B^0 --> pi^- l^+ nu, B^+ --> pi^0 l^+ nu, B^+ --> omega l^+ nu, B^+ -->
eta l^+ nu and B^+ --> eta^' l^+ nu, (l = e or mu) undertaken with
approximately 462x10^6 B\bar{B} pairs collected at the Upsilon(4S) resonance
with the BABAR detector. The analysis uses events in which the signal B decays
are reconstructed with a loose neutrino reconstruction technique. We obtain
partial branching fractions in several bins of q^2, the square of the momentum
transferred to the lepton-neutrino pair, for B^0 --> pi^- l^+ nu, B^+ --> pi^0
l^+ nu, B^+ --> omega l^+ nu and B^+ --> eta l^+ nu. From these distributions,
we extract the form-factor shapes f_+(q^2) and the total branching fractions
BF(B^0 --> pi^- l^+ nu) = (1.45 +/- 0.04_{stat} +/- 0.06_{syst})x10^-4
(combined pi^- and pi^0 decay channels assuming isospin symmetry), BF(B^+ -->
omega l^+ nu) = (1.19 +/- 0.16_{stat} +/- 0.09_{syst})x10^-4 and BF(B^+ --> eta
l^+ nu) = (0.38 +/- 0.05_{stat} +/- 0.05_{syst})x10^-4. We also measure BF(B^+
--> eta^' l^+ nu) = (0.24 +/- 0.08_{stat} +/- 0.03_{syst})x10^-4. We obtain
values for the magnitude of the CKM matrix element V_{ub} by direct comparison
with three different QCD calculations in restricted q^2 ranges of B --> pi l^+
nu decays. From a simultaneous fit to the experimental data over the full q^2
range and the FNAL/MILC lattice QCD predictions, we obtain |V_{ub}| = (3.25 +/-
0.31)x10^-3, where the error is the combined experimental and theoretical
uncertainty.
08/2012;
