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We present an update on total and partial branching fractions and on CP asymmetries in the semi-inclusive decay B 2!Xsll-. Further, we summarize our results on branching fractions and CP asymmetries for semi-inclusive and fully-inclusive B 2!Xs[gamma] decays. We present the first result on the CP asymmetry diff erence of charged and neutral B 2!Xs[gamma] decays yielding the first constraint on the ratio of Wilson coeffi cients Im(C8eff/C7eff).
We describe a measurement of the direct CP asymmetry between inclusive b 2!s[gamma] and {bar b} 2!{bar s}[gamma] decays. This asymmetry is expected to be less than 0.01 in the Standard Model, but could be enhanced up to about 0.10 by new physics contributions. We use a sample of 89 million B{bar B} pairs recorded with the BABAR detector at PEP-II, from which we reconstruct a set of 12 exclusive b 2!s[gamma] final states containing one charged or neutral kaon and one to three pions. We measure an asymmetry of A{sub CP} (b 2!s[gamma]) = 0.025 ± 0.050(stat.) ± 0.015(syst.), corresponding to an allowed range of -0.06
We perform a measurement of the CP asymmetry in b → s[gamma] decays using a sample of 383 x 106 B{bar B} events collected by the BABAR detector at the PEP-II asymmetric B factory. We reconstruct sixteen flavor-specific B decay modes containing a high-energy photon and a hadronic system X{sub s} containing an s quark. We measure the CP asymmetry to be -0.011 ± 0.030(stat) ± 0.014(syst) for a photon energy threshold at 1.6 GeV and the hadronic system mass between 0.6 and 2.8 GeV/c2.
In this thesis, I describe a study of the CP asymmetry in [beta] --> [sigma] [gamma] decays. This CP asymmetry is expected to be less than 0.01 in the Standard Model, but could be enhanced up to the order of 0.10 by non-Standard Model contributions. We use a sample of 383 x 106 BB events collected by the BABAR detector at the PEP-II asymmetric B factory and reconstruct sixteen flavor-specific B decay modes containing a high energy photon and a hadronic Xs system. We measure the CP asymmetry to be -0.011 ± 0.030stat ± 0.014syst for a photon energy threshold at 1.6 GeV and the hadronic system mass between 0.6 and 2.8 GeV/c2.
We perform a measurement of direct CP violation in b to s+gamma Acp, and the measurement of a difference between Acp for neutral B and charged B mesons, Delta A_X_sgamma, using 429 inverse femtobarn of data recorded at the Upsilon(4S) resonance with the BABAR detector. B mesons are reconstructed from 16 exclusive final states. Particle identification is done using an algorithm based on Error Correcting Output Code with an exhaustive matrix. Background rejection and best candidate selection are done using two decision tree-based classifiers. We found A_cp = 1.73%+-1.93%+-1.02% and Delta A_X_sgamma = 4.97%+-3.90%+-1.45% where the uncertainties are statistical and systematic respectively. Based on the measured value of Delta A_X_sgamma, we determine a 90% confidence interval for Im C_8g/C_7gamma, where C_7gamma and C_8g are Wilson coefficients for New Physics amplitudes, at -1.64
This dissertation describes a measurement of the direct CP asymmetry between inclusive b {yields} s{gamma} and {bar b} {yields} {bar s}{gamma} decays. This asymmetry is expected to be less than 0.01 in the Standard Model, but could be enhanced up to the order of 0.10 by non-Standard Model contributions. We use a sample of 89 million B{bar B} pairs recorded with the BABAR detector at PEP-II, from which we reconstruct a set of 12 exclusive b {yields} s{gamma} final states containing one charged or neutral kaon and one to three pions. We measure an asymmetry of A{sub CP} (b {yields} s{gamma}) = 0.025 {+-} 0.050(stat.) {+-} 0.015(syst.), corresponding to an allowed range of -0.06
The b [yields] s[gamma] decay represents a possible electromagnetic ''loop'' penguin decay of the B meson. This FCNC process is of high theoretical interest because various scenarios of new physics are expected to have contributions at the same (one loop) level as the Standard Model. The large sample of B[bar B] meson decays collected by the BaBar experiment makes a precision measurement of this rare decay possible. In conjunction with Standard Model predictions at the 10% level, it brings new physics effects into the realm of detection--or seriously constrains models that could predict them. A fully inclusive technique is presented to study the b [yields] s[gamma] transition as a function of photon energy, using 88.5 [+-] 1.0 x 10[sup 6] B[bar B] meson decays collected by the BaBar experiment in the years 2000 to 2002. The expected statistical and systematic uncertainties have been fully determined which enables first comparisons with theoretical predictions and other experimental results. It also lays the basis for the determination of the inclusive branching fraction [Beta](B [yields] X[sub s][gamma]) and the measurement of the photon energy spectrum.
The authors present new CDF results on the branching fractions and time-integrated direct CP asymmetries for B{sup 0} and B{sub s}{sup 0} decay modes into pairs of charmless charged hadrons (pion or kaon). The data set for this update amounts to 1 fb{sup -1} of {bar p}p collisions at {radical}s = 1.96 TeV. They report the first observation of the B{sub s}{sup 0} {yields} K{sup -}{pi}{sup +} mode and a measurement of its branching fraction and direct CP asymmetry. They also observe for the first time two charmless decays of b-baryon: {Lambda}{sub b}{sup 0} {yields} p{pi}{sup -} and {Lambda}{sub b}{sup 0} {yields} pK{sup -}.