Determination of the b-quark mass and nonperturbative parameters in semileptonic and radiative penguin decays at BABAR
Kerstin Tackmann
备注：
Contributed to the proceedings of the 12th International Conference on Hadron Spectroscopy (Hadron 07), Frascati, Italy, 8-13 Oct 2007. 7pp, 4 figures. v2: Replaced Fig. 3 (b) with correct version
Knowing the mass of the b-quark is essential to the study of the structure and decays of B mesons as well as to future tests of the Higgs mechanism of mass generation. We present recent preliminary measurements of the b-quark mass and related nonperturbative parameters from moments of kinematic distributions in charmed and charmless semileptonic and radiative penguin B decays. Their determination from charmless semileptonic B decays is the first measurement in this mode. The data were collected by the BABAR detector at the PEP-II asymmetric-energy e+e- -collider at the Stanford Linear Accelerator Center at a center-of-momentum energy of 10.58 GeV.
We summarize results on a number of observations of penguin dominated radiative decays of the B meson. Such decays are forbidden at tree level and proceed via electroweak loops. As such they may be sensitive to physics beyond the standard model. The observations have been made at the BaBar experiment at PEP-II, the asymmetric B factory at SLAC.
We report measurements of Time-Dependent CP asymmetries in several $b\to s$ penguin dominated hadronic B decays, where New Physics contributions may appear. We find no significant discrepancies with respect to the Standard Model expectations.
We report recent results in the study of rare hadronic and radiative penguin decays of B mesons. These results are based on a sample of 23 million B B-bar pairs collected by the BaBar Collaboration at the SLAC PEP-II e+e- B Factory.
We present recent results from the \babar Collaboration on radiative decays. These include searches for new physics via measurements of several observables such as the time-dependent $CP$ asymmetry in $B^0 \to K^0_S π^- π^+ γ$ exclusive decays, as well as direct $CP$ asymmetries and branching fractions in $B \to X_s γ$ and $B \to X_s \ell^+ \ell^-$ inclusive decays.
This article summarises measurements of time-dependent CP asymmetries in decays of neutral B mesons to charmonium, open-charm and gluonic penguin-dominated charmless final states. Unless otherwise stated, these measurements are based on a sample of approximately 230 million Y(4S) to BBbar decays collected by the BABAR detector at the PEP-II asymmetric-energy B-factory.
We report recent results from the BABAR experiment on semileptonic charmless B-meson decays and electroweak penguin processes. Semileptonic charmless decays are used to determine |Vub| and the exclusive modes considered here also begin to constrain QCD-lattice form factor calculations. Radiative penguin decays are both sensitive to physics beyond the Standard Model and can be used to extract Heavy Quark parameters related to the b-quark mass and its motion inside the hadron.
Electro-weak penguin and leptonic decays provide an indirect probe for physics beyond the Standard Model and contribute to the determination of Standard Model parameters. Copious quantities of B mesons produced at the B-Factories permit precision measurements of the electro-weak penguin decays and searches for leptonic decays. We review the current experimental status of b -> s(d) gamma, B^0 -> D^{*0} gamma, b -> s l^+ l^- and finally B->tau nu decays at BaBar.
We present preliminary measurements of time-dependent CP-violation parameters in the decays B0->omegaK0S, B0->eta'K0, B0->pi0K0S, B0->phiK0Spi0, and B0->K+K-K0S, which includes the resonant final states phiK0S and f0(980)K0S. The data sample corresponds to the full BABAAR dataset of 467 million BBbar pairs produced at the PEP-II asymmetric-energy e+e- collider at the Stanford Linear Accelerator Center.
Recent BaBar results on rare B decays involving flavour-changing neutral currents or purely leptonic final states are presented. New measurements of the CP asymmetries in B -> K* gamma, B -> K*2(1430) gamma, and b -> s gamma are reported, as well as a new measurement of the B -> K* gamma branching fraction. Also reported are updated limits on B -> mu nu and recent measurements of B -> K* l+ l- and b -> s l+ l-. The data sample comprises 123 10^6 Y4S -> B Bbar decays collected with the BaBar detector at the PEP-II e+e- storage ring.
We report measurements of charmonium resonances (J/Psi, Psi(2S),Chi_c1) using about 25 fb^-1 of data collected by the BABAR detector around the Upsilon(4S) resonance. We present measurements of inclusive charmonium production of charmonium in B decays and from the continuum, as well as exclusive branching ratios of B mesons into charmonium final states. We present also a measurement of the B0 -> K*0 gamma branching ratio and a search for the decay B0 -> gamma gamma.
BaBar measurements involving semileptonic decays of B mesons are reviewed. Attention is focused on the extraction of |Vub| and |Vcb| elements of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. Recent results of inclusive and exclusive approaches are presented.
Studies of semileptonic $B_s$ decays by the Belle, Babar and D0 experiments are reported. In particular measurements of inclusive semileptonic $B_s$ decays by Belle and Babar and the exclusive excited charm mode $B_s \to D_{s1} μν$ from D0 are presented. An outlook on further semileptonic $B_s$ measurements with $Υ(5S)$ data at Belle and Belle II is also given.
Some recent Babar results on semileptonic decays are presented. They focus on the determination of the CKM matrix elements |V_{ub}| and |V_{cb}| in inclusive and exclusive b --> u l nu and b--> c l nu decays, and on form factors measurement in exclusive c--> s l nu decays.
Radiative and electroweak decays of B mesong (B to X_{s(d)}γ and B to X_{s(d)}\ell\ell, respectively, where X is a hadronic system and s or d labels the underlying quark process b to s(d)γ) provide good places to search for new physics (NP) beyond the standard model. Recent BaBar measurements are reported: inclusive BF(B to X_s γ), direct CP asymmetry for inclusive X_s γ and X_{s+d} γ, and searches for the rare decays B to π(η)\ell\ell. No evidence for NP was found, but several constraints are discussed.
We present a preliminary measurement of the branching fraction of the exclusive penguin decay B^0 -> K^*0 gamma using (8.6+/-0.3) x 10^6 B-anti-B decays BF(B^0 -> K^*0 gamma) = (5.2+/-0.82 (stat.) +/- 0.47 (sys.)) x 10^-5. In addition we search for the related penguin decays with a lepton pair in the final state, B^+ -> K^+ l^+l^-, B^0 -> K^*0 l^+l^-. We find no evidence for these decays in 3.7+/-0.1 x 10^6 B-anti-B decays and set preliminary 90% C.L upper limits of BF(B^+ -> K^+ e^+ e^-) < 12.5 x 10^{-6}, BF(B^+ -> K^+ mu^+ mu^-) < 8.3 x 10^{-6}, BF(B^0 -> K^*0 e^+ e^-) < 24.1 x 10^{-6}, BF(B…
We present measurements of the inclusive semileptonic branching fractions of charged and neutral B mesons using 20.6 fb-1 of data measured at the Upsilon(4S) with the BABAR detector. Events are tagged with a fully reconstructed hadronic decay of a B meson. The correlation between the flavor of the tag B meson and the electron charge allows the separation of prompt semileptonic B decays and cascade semileptonic charm decays. We obtain the preliminary inclusive semileptonic branching fraction of charged B mesons b+ = 0.103+/-0.006+/-0.005, neutral B mesons b0 = 0.104+/-0.008+/-0.005, their avera…
We present the new and updated $BABAR$ measurements of CP-violation studies for many $b\to s $ penguin decay modes. We report the first observation of mixing-induced CP-violation in $B^0 \to η^{'} K^0$ with a significance (including systematic uncertainties) of 5.5$σ$. We also present the first observation of the decay $B^0 \to ρ^0 K^0$. Using the time-dependent Dalitz plot analysis of $B^0\to K^+K^- K^0$ decay, the CP-parameters $\mathcal A_{CP}$ and $β_{eff}$ are measured with $4.8σ$ significance, and we reject the solution near $π/2 - β_{eff}$ at $4.5σ$. We also present the updated measurem…
We report on preliminary results of searches for penguin mediated B decays based on 20.7 fb^{-1} of data collected at the Y(4S) peak with the BABAR detector at PEP-II. The following branching fractions have been measured: BR(B+ --> phi K+) = (7.7^{+1.6}_{-1.4} +- 0.8)*10^{-6}, BR(B0 --> phi K0) = (8.1^{+3.1}_{-2.5} +- 0.8)*10^{-6}, BR(B+ --> phi K*+) = (9.7^{+4.2}_{-3.4} +- 1.7)*10^{-6}, BR(B0 --> phi K*0) = (8.7^{+2.5}_{-2.1} +- 1.1)*10^{-6}, BR(B+--> omega pi+) = (6.6^{+2.1}_{-1.8} +- 0.7)*10^{-6}, BR(B --> eta K^*0) = (19.8^{+6.5}_{-5.6} +-1.7)*10^{-6}, where the first error is statistical …
Presented are selected results of semileptonic B decays at BaBar. Two measurements of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ are reported. One using moments of the hadronic-mass spectrum in inclusive $\bar{B} \to X_{c} \ell^{-} \barν$ decays, and the other, exclusive $\bar{B} \to D \ell^- \barν_{\ell}$ decays. These results are based on data samples of 232 (inclusive $\bar{B} \to X_{c} \ell^{-} \barν$) and 460 (exclusive $\var{B} \to D \ell^- \barν_{\ell}$) million $Υ(4S) \to B\bar{B}$ decays, recorded by the $BaBar$ detector at the PEP-II $e^+e^-$-storage rings. Semileptonic …
We present results on semileptonic B decays obtained with the BABAR detector. The large data set accumulated at the PEP-II asymmetric-energy B-Factory allows a new measurement technique, where the hadronic decay of one B meson is fully reconstructed and the semileptonic decay of the recoiling B meson is studied. Traditional analysis techniques of inclusive and exclusive B decays complement this approach with very high statistics data samples. These measurements play an important role in the tests of the description of CP violation in the Standard Model: The determinations of the Cabibbo-Kobaya…
This article gives an overview of the recent searches and measurements of $b\to d$ penguin transitions with the BaBar experiment. The branching fraction of these decays in the Standard Model (SM) is expected to be a factor of 10 or more lower than the corresponding $b\to s$ penguin transitions, but a deviation from the SM prediction would be an equally striking sign of new physics. The exclusive decay $B\toπ\ell\ell$ is searched by BaBar with no excess over the background found. The BaBar measurement of $B\to(ρ,ω)γ$ provides the first evidence of $B^+\toρ^+γ$, is in good agreement with the pre…
The Belle~II Collaboration presents four new analyses: The measurement of $V_{ub}$ from $B \to πe ν_e$ decays with a fit to the differential $q^2$ spectrum, the determination of $V_{cb}$ using a fit to the differential $w$ distribution from $B^0 \to D^{\ast -} \ell^+ ν_\ell$ decays, and the measurement of $q^2$ moments in inclusive $B \to X_c \ell ν_\ell$ decays. In all these analyses tag-side $B$ meson is reconstructed in a fully hadronic decay chain. The last result are branching fraction measurement of $B \to K^\ast \ell^+ \ell^-$ decays using an untagged approach.
We report updates on two analyses of inclusive semileptonic B decays based on a dataset of 89 million BB events recorded with the BABAR detector at the Y(4S) resonance. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other B meson. In the first analysis, the measurement of the first and second moment of the hadronic mass distribution in Cabibbo-favored B ->X_c l nu decays allows for the determination of the nonperturbative parameters $\barΛ$ and $λ_1$ of Heavy Quark Effective Theory (HQET) and |Vcb|. In the second anal…
We present a preliminary measurement of the branching fraction for B to rho e nu and of the CKM matrix element |Vub| using approximately 55 million B Bbar meson pairs collected with the BABAR detector. Using isospin relations for several modes we find BF(B0 to rho- e+ nu) = (3.39+-0.44+-0.52+-0.60)x10^(-4) and |Vub| = (3.69+-0.23+-0.27+0.40-0.59)x10^(-3). The quoted errors are statistical, systematic, and theoretical, respectively. These results are obtained by using five different form-factor calculations.
A measurement of the first four moments of the hadronic mass distribution in B->Xc lv decays is presented for minimum lepton momenta varying between 0.9 and 1.6 GeV, using data recorded with the BaBar detector. Furthermore, a measurement of the inclusive electron energy spectrum for semileptonic B decays together with a measurement of its first, second and third moments for minimum electron energies between 0.6 and 1.5 GeV is reported. We determine the inclusive B->Xc lv branching fraction, B_clv, the CKM matrix element |V_cb|, and other heavy-quark parameters from a simultaneous fit to the me…
In this note, recent results of studies of semileptonic B meson decays from \babar are discussed and preliminary results given. In particular, a recent measurement of $\mathcal{B}(B \to D^{(*)}τν)$ and the ratio $\mathcal{B}(B \to D^{(*)}τν)/\mathcal{B}(B \to D^{(*)}\ell ν)$ is presented. For the $D^*$ mode, a branching fraction of $1.79\pm0.13\stat\pm0.17\syst$ is found, with a ratio of $0.325\pm0.023\stat\pm0.027\syst$. For the $D$ mode, the results are $1.04\pm0.12\stat\pm0.14\syst$ and $0.456\pm0.053\stat\pm0.056\syst$, respectively. In addition, a study of $B_s$ production and semileptoni…
The BABAR experiment has completed its first year of data-taking during which 21 $fb^{-1}$ of data were accumulated. We present preliminary results on two types of charmless B decays based on this data sample. The first, $B^0 \to K^{*0}γ$, is a so-called electromagnetic penguin. And the second, $B^0 \to h^+h^{'-}$, where $h^{(')}$ can be either a pion or kaon, can come from either penguin diagrams or Cabibbo suppressed tree diagrams.
We present recent results from the BaBar collaboration in several areas of research. These include searches for new physics via measurements of radiative-penguin B decays, lepton-number and lepton-flavor violations in B decays, and CP violation in tau lepton decays.
In this article, I review the most recent results in radiative penguin decays from the B factories Belle and Babar. Most notably, I will talk about the recent new observations in the decays B -> (rho/omega) gamma, a new analysis technique in b -> s gamma, and first measurements of radiative penguin decays in the B_s meson system. Finally, I will summarize the current status and future prospects of radiative penguin B physics at the B factories.
Recent branching fraction and asymmetry results of Electroweak Penguin B decays from BaBar, Belle and CLEO experiments are reviewed. While these branching fractions are consistent with the Standard Model expectations and are being used to extract heavy quark model parameters and CKM matrix elements, the asymmetry results are just becoming sensitive to observe any new physics effects.
We begin with giving some motivation for the study of charm semileptonic and fully leptonic decays. We turn next to a discussion of semileptonic absolution branching fraction results form CLEO-c. Two exciting high statistics results on fully leptonic decays of the D+ -> mu+ nu and Ds+ -> mu+ nu from CLEO-c and BaBar are reviewed. We turn next to a discussion of recent results on charm meson decay to pseudo-scalar l nu decays from FOCUS, BaBar, and CLEO-c. We conclude with a review of charm meson decay into Vector l nu.
We present measurements related to the CKM angle beta from BABAR based on 82 or ~115 fb-1 data samples collected at the PEP-II e+e- asymmetric B Factory collider. A new method allowing to measure the sign of cos(2.beta) with B0->J/Psi"K*0" events is explained and related results reported. Recent CP measurements in the penguin dominated modes B0->phi K0,B0->K+K-K0s, B0->pi0 K0s and B0->f0(980) K0s are presented.
We review the recent results on D and D_s meson semileptonic decays from CLEO-c, BABAR, and Belle. Comparisons with lattice quantum chromodynamics (LQCD) calculations and implications for B physics are also discussed.
We present preliminary measurements of CP-violating asymmetries in B decays. These include new results on the CKM angle alpha based on studies of the decay B -> rho+ rho- and several charmonium and hadronic penguin modes, sensitive to the CKM angle beta, including results on B -> phi K0S, B -> K+K-K0, B -> eta' K0S, B -> f0 K0, and B -> pi0 K0S. We also report on several of results related to the extraction of gamma and (2*beta+gamma) and present limits on CPT violation in B decays.
Electromagnetic radiative penguin decays of the B meson were studied with the BaBar detector at SLAC's PEP-II asymmetric-energy B Factory. Branching fractions and isospin asymmetry of the decay B -> K* gamma, branching fractions of B -> K2*(1430) gamma, and a search for B0 -> phi gamma are presented. The decay rates may be enhanced by contributions from non-standard model processes.
A preliminary measurement of the second moments of the hadron mass in B --> X l nu decays by the BABAR Collaboration is reported. These measurements are performed as a function of the lepton momentum above a given threshold.
We report on new measurements of the Cabibbo-Kobayashi-Maskawa matrix elements |V_{cb}| and |V_{ub}| with inclusive and exclusive semileptonic B decays, highlighting the recent precision measurements with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC.
We present the results of searches for rare B meson decays. The measurements use all or part of a data sample of about 88 million $Υ(4S)\to B{\bar B}$ decays collected between 1999 and 2002 with the \babar detector at the PEP-II asymmetric energy B Factory at the Stanford Linear Accelerator Center. We study a variety of decays dominated by electromagnetic, electroweak and gluonic penguin transitions, and report measurements of branching fractions and other quantities of interest.
A sample of 23 million B B-bar events collected with the BABAR detector at the PEP-II collider is used in a search for direct CP violation in charmless two-body B decays, quasi two-body B decays, and the radiative penguin decays B to K* gamma. No evidence for direct CP violation is found in the considered modes and 90% confidence level limits are reported. We also present a limit on the branching fraction of the decay B0 to gamma gamma.
The CKM matrix element amplitude |V_cb| was determined using the data collected by the BABAR detector. The partial branching fraction, lepton-energy moments, and hadron-mass moments were measured in inclusive semileptonic decays B -> X_c l nu. A global fit to a Heavy-Quark-Expansion calculation allowed precise determination of |V_cb|, m_b, m_c, B(B -> X_c l nu) and four non-perturbative parameters.
We present the measurements of the CKM matrix parameters Vub, Vcb and of the B mixing oscillation frequency with the BaBar experiment at the asymmetric B-factory PEPII. Data were collected in the years 2000-2002 and the total available statistics corresponds to 91 fb-1. The Vub, Vcb measurements utilize both inclusive and exclusive semileptonic decays of the $B$ meson. The Delta(md) parameter is measured by using the time evolution of the B, determined from the flight length difference between the two B mesons.
We describe measurements of CP and CPT violation parameters in B^0B^0bar oscillations, performed at BaBar by using BBbar events collected at the Y(4S) mass peak. These are obtained from two different B-reconstruction methods, namely: searching for two inclusive semileptonic B^0 decays in an event or partially reconstructing one of the B^0 mesons in the D* l nu_l channel. The results are in agreement with one another and with the most recent theoretical calculations in the Standard Model scenario.
We report on preliminary measurements of time-dependent CP asymmetries in neutral B decays to CP eigenstates with transition amplitudes that are dominated by penguin-type loops. The results are obtained from a data sample of up to 227 million Upsilon(4S)->BB-bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B-meson Factory at SLAC. The amplitudes of the effective mixing-induced CP asymmetries, sin(2beta)_eff, are derived from decay-time distributions of events in which one neutral B meson is fully reconstructed in a final state without charm and the other B meson is …
A largely model-independent measurement of the inclusive electron momentum spectrum and branching fraction for semileptonic decays of B mesons is presented based on data recorded at the Upsilon(4S) resonance with the BABAR detector. Backgrounds from secondary charm decays are separated from prompt B decays using charge and angular correlations between the electron from one B meson and a high momentum electron tag from the second B meson. The resulting branching fraction is BR(B -> X e nu) = (10.87 +-0.18(stat)+-0.30(syst))%. Based on this measurement we determine the CKM matrix element |V_cb|.
We present recent results of B and charm decays from the BaBar experiment. These results include searches for rare or forbidden charm decays, measurements of $|V_{ub}|$ from inclusive ${\bar B} \rightarrow X_u l {\bar ν} $ decays, observation of the semileptonic ${\bar B} \rightarrow D^{(*)} τ^- {\bar ν}_τ$ decays, direct CP violation asymmetry in $B \rightarrow X_{s+d} γ$ and in $D^+\rightarrow K^0_S π^+$, and T-violation in $D^+_{(s)} \rightarrow K^+ K^0_S π^+ π^-$. These studies are based on the final dataset collected by BaBar at the PEP-II B factory at SLAC in the period 1999-2008.
We present a measurement of the inclusive electron spectrum in charmless semileptonic B decays near the kinematic limit for B->X_c eνtransitions, using a sample of 88 million Upsilon(4S) decays recorded by the BABAR detector. Partial branching fraction measurements are performed in five overlapping intervals of the electron momentum. For the interval of 2.0-2.6 GeV/c we obtain ΔBr(B->X_u eν) = (0.572+-0.041(stat)+-0.065(syst))x10^{-3}. Combining this result with shape function parameters extracted from BABAR measurements of moments of the inclusive photon spectrum in B->X_s+gamma decays and mo…
We present the first evidence for B semileptonic decays into the charmed baryon Lambda_c+ based on 420 fb-1 of data collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II e+e- storage rings. Events are tagged by fully reconstructing one of the B mesons in a hadronic decay mode. We measure the relative branching fraction BF(Bbar -> Lambda_c+ X l- nubar_l)/BF(Bbar -> Lambda_c+/Lambda_c- X) = (3.2 +/- 0.9_stat +/- 0.9_syst)%. The significance of the signal including the systematic uncertainty is 4.9 standard deviations.
The following is an overview of the current status of charmless semileptonic B decays and the extraction of the CKM matrix element $|V_{ub}|$ by the Belle and BaBaR collaborations.
Recent results from BaBar and Belle experiments on $B \bar B$ mixing and $\sin 2ϕ_1$ are presented. Accuracy of $Δm_d$ measurements has reached 1.2%. Higher order effects within the Standard Model or possible new physics effect that might appear in the $B \bar B$ mixing through non-zero $ΔΓ/Γ$, CP violation, or $CPT$ violation have been explored. The BaBar and Belle results on $\sin 2ϕ_1$ from the $b \to c \bar{c} s$ modes are in good agreement with each other and a combined result with an accuracy of 8% is in good agreement with a global CKM fit. A simple average of the $\sin 2ϕ_1$ values tha…
The huge datasets collected at the two B factories, Belle and BaBar, have made it possible to explore the radiative penguin process b --> s gamma, the electroweak penguin process b --> s l+ l- and the suppressed radiative process b --> d gamma in detail, all in exclusive channels and inclusive measurements. Theoretical tools have also advanced to meet or surpass the experimental precision, especially in inclusive calculations and the various ratios of exclusive channels. In this article, we review the theoretical and experimental progress over the past decade in the radiative and electroweak p…
A search for the decays B --> rho(770) gamma and B0 --> omega(782)gamma is performed on a sample of 211x10^6 Y(4S)->BBbar events collected by the BABAR detector at the PEP-II asymmetric-energy e+e- storage ring. No evidence for the decays is seen. We set the following limits on the individual branching fractions: BF(B --> rho+ gamma)<1.8 x 10^-6, BF(B --> rho0 gamma)<0.4 x 10^-6, and BF(B --> omega gamma)<1.0 x 10^-6 at the 90% confidence level (C.L.). We use the quark model to limit the combined branching fraction BFbar[B --> (rho/omega) gamma]<1.2 x 10^-6, from which we determine a constrain…
We present measurements of the semileptonic decays B- --> D0 tau- nubar, B- --> D*0 tau- nubar, B0bar --> D+ tau- nubar, and B0bar --> D*+ tau- nubar, which are potentially sensitive to non--Standard Model amplitudes. The data sample comprises 232x10^6 Upsilon(4S) --> BBbar decays collected with the BaBar detector. From a combined fit to B- and B0bar channels, we obtain the branching fractions B(B --> D tau- nubar) = (0.86 +/- 0.24 +/- 0.11 +/- 0.06)% and B(B --> D* tau- nubar) = (1.62 +/- 0.31 +/- 0.10 +/- 0.05)% (normalized for the B0bar), where the uncertainties are statistical, systematic,…
We present several alternative techniques used by the BaBar Collaboration in order to measure the Unitarity Triangle angle gamma. We also present the results of two searches designed to improve the measurements of sin(2beta) using penguin B decay modes by reducing the hadronic corrections uncertainties.
We study glueball G production in gluonic penguin decay B -> X_s G, using next-to-leading order b -> s g^* gluonic penguin interaction and an effective coupling of a glueball to two gluons. The effective coupling allows us to study the decay rate of a glueball to two pseudoscalars in the framework of chiral perturbation theory. Identifying the f_0(1710) to be a scalar glueball, we then determine the effective coupling strength with the branching ratio of f_0(1710) -> K KBar. We find that the charm penguin to be important and obtain a sizable branching ratio for Br(B -> X_s G) in the range of (…
We present a search for the decay B+ -> tau+ nu using 288 inverse femtobarns of data collected at the Upsilon(4S) resonance with the BaBar detector at the SLAC PEP-II B-Factory. A sample of events with one reconstructed semileptonic B decay (B- -> D0 l- nu X) is selected, and in the recoil a search for the signal decay mode is performed. The tau is identified in four channels. We measure a branching fraction of BF(B+ -> tau+ nu) = (0.88+0.68 -0.67(stat.) +- 0.11(syst.)) x 10^{-4} and extract an upper limit on the branching fraction, at the 90% confdence level, of 1.8 x 10^{-4}.
We report studies of semileptonic decays, B --> X_c l nu, based on a sample of 88 million BB events recorded with the BABAR detector. We have measured four moments of the electron energy distribution and four moments of the hadronic mass distribution, each as a function of the minimum electron energy. From these moments we determine the inclusive branching fraction, the CKM matrix element |V_cb|, and other heavy quark parameters, using Heavy Quark Expansions (HQE) to order 1/m_b^3 in the kinetic mass scheme. In addition, we have studied a large sample of exclusive B^0 --> D^*- l^+ nu decays. T…
In this review, the most recent results of the radiative decays B -> X_s gamma, B -> K^{(*)} l^+ l^-$ and B -> pi/eta l^+ l^- at e^+e^- colliders are discussed. The new, most precise CP asymmetry measurements in B -> X_s gamma from BABAR are presented together with branching fractions and photon energy moments. For B -> K^{(*)} l^+ l^- modes, B factory results on partial branching fractions, rate asymmetries and angular observables are combined with measurements from CDF and the LHC experiments. The first branching fraction upper limits for B -> eta l^+ l^- are shown along with updated upper l…
The b-->d penguin-dominated modes B-->KKbar have been observed at the B factories. In addition, the BaBar Collaboration has reported the first time-dependent CP-violation measurement in B0-->K0K0bar.
