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We present a measurement of the branching fractions for the Cabibbo-favored radiative decay, D° → {bar K}*°?, and the Cabibbo-suppressed radiative decay, D° →??. These measurements are based on a data sample corresponding to an integrated luminosity of 387.1 fb−1, recorded with the BABAR detector at the PEP-II ee− asymmetric-energy collider operating at center-of-mass energies 10.58 and 10.54 GeV. We measure the branching fractions relative to the well-studied decay D° → K−?+ and find?(D° → {bar K}*°?)/?(D° → K−?+) = (8.43 ± 0.51 ± 0.70) x 10−3 and?(D° →??)/?(D° → K−?+) = (7.15 ± 0.78 ± 0.69) x 10−4, where the first error is statistical and the second is systematic. This is the first measurement of?(D° → {bar K}*°?).
This dissertation presents a simultaneous measurement of the branching fractions of ten B --> D{sup (*)}{bar D}{sup (*)} decays. The measurements are derived from a sample of 2.32 x 108 B{bar B} pairs collected by the BABAR detector at the PEP-II B Factory located at Stanford Linear Accelerator Center. The branching fractions (x 10−4) are: -0.10 ± 0.44 ± 0.15 (0.59) for B° -- D°{bar D}°; 1.01 ± 1.07 ± 0.35 (2.92) for B° -- D*°{bar D}°; -1.31 ± 1.05 ± 0.41 (0.92) for B° -- D*°{bar D}*°; 2.81 ± 0.43 ± 0.45 for B° --> DD−; 5.72 ± 0.64 ± 0.71 for B° --> D*D−; 8.11 ± 0.57 ± 0.97 for B° --> D*+D*−; 3.76 ± 0.57 ± 0.45 for B− --> D−D°; 3.56 ± 0.52 ± 0.39 for B− --> D*−D°; 6.30 ± 1.32 ± 0.93 for B− --> D−D*°; and 8.14 ± 1.17 ± 1.11 for B− --> D*−D*°. The first uncertainty is statistical while the second is systematic. The number in parentheses is the 90% upper limit using the Feldman-Cousins method with systematic uncertainties taken into account. These measurements are consistent with the Standard Model predictions using the factorization assumption.
This 2nd edition is an extensive update of 'B Decays”. The revisions are necessary because of the extensive amount of new data and new theoretical ideas. This book reviews what is known about b-quark decays and also looks at what can be learned in the future.The importance of this research area is increasing, as evidenced by the approval of the luminosity upgrade for CESR and the asymmetric B factories at SLAC and KEK, and the possibility of experiments at hadron colliders.The key experimental observations made thus far, measurement of the lifetimes of the different B species, B0-B0 mixing, the discovery of “Penguin” mediated decays, and the extraction of the CKM matrix elements Vub and Vcb from semileptonic decays, as well as more mundane results, are described in great detail by the experimentalists who have been closely involved with making the measurements. Theoretical progress in understanding b-quark decays using HQET and lattice gauge techniques are described by theorists who have developed and used these techniques.Synthesizing the experimental and theoretical information, several articles discuss the implications for the “Standard Model” and how further tests can be done using measurements of CP violation in the B system.
A measurement of the radiative muon decay [mu] --> e v e̳ v [m̳u̳] [gamma] branching fraction was done on the basis of the radiative decay data of MEG experiment. The data were taken periodically one day per week with the beam intensity of 1.2x106 [mu] + / s from September to December, 2008. The positron was measured by a spectrometer with gradient magnetic field. The photon was detected by an innovative ̃900 liter liquid xenon scintillation detector. The measurement was carried out with a cut-and-count approach. We report the radiative muon decay branching fraction to be B([mu] --> e vv̄ [gamma]) = (2.84 ± 0.20(stat) ± 0.05(syst))x10−7, with Ee̳> 46 MeV, E [gamma]> 30 MeV, and the opening angle between the two particles [theta] e̳ [gamma] in its full kinematic range. Distributions of three observables, E e̳, E [gamma], and [theta] e̳ [gamma], as well as their kinematic correlations were verified to be consistent with the radiative decays. The measurement is in excellent agreement with the prediction of the Standard Model.
The results of several studies of charmed mesons and baryons at BABAR are presented. First, searches for the rare decays D{sup 0} {yields} l{sup +}l{sup -} are presented and new upper limits on these processes are established. Second, a measurement of the branching fraction of the isospin-violating hadronic decay D*{sub s}(2112){sup +} {yields} D{sub s}{sup +}{pi}{sup 0} relative to the radiative decay D*{sub s}(2112){sup +} {yields} D{sub s}{sup +}{gamma} is made. Third, the decays of D*{sub sJ}(2317){sup +} and D{sub sJ}(2460){sup +} mesons are studied and ratios of branching fractions are measured. Fourth, Cabibbo-suppressed decays of the {Lambda}{sub c}{sup +} are examined and their branching fractions measured relative to Cabibbo-allowed modes. Fifth, the {Chi}{sub c}{sup 0} is studied through its decays to {Chi}{sup -}{pi}{sup +} and {Omega}{sup -}K{sup +}; in addition to measuring the ratio of branching fractions for {Chi}{sub c}{sup 0} produced from the c{bar c} continuum, the uncorrected momentum spectrum is measured, providing clear confirmation of {Chi}{sub c}{sup 0} production in B decays.
The standard model has been highly successful at describing current experimental data. However, extensions of the standard model predict particles that have masses at energy scales that are above the electroweak scale. The flavor-changing neutral current processes of the B meson are sensitive to the influences of these new physics contributions. These processes proceed through loop diagrams, thus allowing new physics to enter at the same order as the standard model. New physics may contribute to the enhancement or suppression of rate asymmetries or the decay rates of these processes. The transition B 2!V? (V = K*(892),?(770),?(782),?(1020)) represents radiative decays of the B meson that proceed through penguin processes. Hadronic uncertainties limit the theoretical accuracy of the prediction of the branching fractions. However, uncertainties, both theoretical and experimental, are much reduced when considering quantities involving ratios of branching fractions, such as CP or isospin asymmetries. The most dominant exclusive radiative b 2!s transition is B 2!K*?. We present the best measurements of the branching fractions, direct CP, and isospin asymmetries of B 2!K*?. The analogous b 2!d transitions are B 2!?? and B 2!??, which are suppressed by a factor of.
The authors report on the inclusive branching fractions of B[sup -] and of [bar B][sup 0] mesons decaying to D[sup 0]X, [bar D][sup 0]X, D[sup +]X, D[sup -]X, D[sub s][sup +]X, D[sub s][sup -]X, [Lambda][sub c][sup +]X, [bar [Lambda]][sub c][sup -]X, based on a sample of 88.9 million B[bar B] events recorded with the BABAR detector at the [Upsilon](4S) resonance. Events are selected by completely reconstructing one B and searching for a reconstructed charmed particle in the rest of the event. The authors measure the number of charmed and of anit-charmed particles per B decay and derive the total charm yield per B[sup -] decay, n[sub c][sup -] = 1.313 [+-] 0.037 [+-] 0.037 [+-] 0.062[sub -0.043][sup +0.063], and per [bar B][sup 0] decay, n[sub c][sup 0] = 1.276 [+-] 0.062 [+-] 0.058[sub -0.046][sup +0.066] where the first uncertainty is statistical, the second is systematic, and the third reflects the charm branching-fraction uncertainties.
Charmless semileptonic decays, {bar B} 2!X{sub u}l{bar {nu}}, are studied in a sample of 232 million B{bar B} decays recorded with the BABAR detector, in events where the decay of the second B meson is fully reconstructed. Inclusive charmless decays are selected in kinematic regions where the dominant background from semileptonic B decays to charm is reduced by requirements on the hadronic mass M{sub X} and the momentum transfer q2. The partial branching fraction for {bar B} 2!X{sub u}l{bar {nu}} decays for M{sub X} 1.7 GeV/c2 and q2 8 GeV2/c4 is measured to be [Delta][Beta]({bar b} 2!X{sub u}l{bar {nu}}) = (0.87 ± 0.09{sub stat} ± 0.09{sub sys} ± 0.01{sub th}) x 10−3. The CKM matrix element.