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Using a sample of 471 million B{bar B} events collected with the BaBar detector, we study the sum of seven exclusive final states b → X{sub s(d)}?, where X{sub s(d)} is a strange (non-strange) hadronic system with a mass of up to 2.0 Gev/c2. After correcting for unobserved decay modes, we obtain a branching fraction for b → d? of (9.2 ± 2.0(stat.) ± 2.3(syst.)) x 10−6 in this mass range, and a branching fraction for b → s? of (23.0 ± 0.8(stat.) ± 3.0(syst.)) x 10−5 in the same mass range. We find BF(b → d?)/BF(b → s?) = 0.040 ± 0.009(stat.) ± 0.010(syst.), from which we determine.
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 → V[gamma] (V = K*(892), [rho](770), [omega](782), [phi](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 → s transition is B → K*[gamma]. We present the best measurements of the branching fractions, direct CP, and isospin asymmetries of B → K*[gamma]. The analogous b → d transitions are B → [rho][gamma] and B → [omega][gamma], which are suppressed by a factor of.
Using a sample of 383 million B{bar B} events collected by the BABAR experiment, they measure sums of seven exclusive final states B → X{sub d(s)}[gamma], where X{sub d}(X{sub s}) is a non-strange (strange) charmless hadronic system in the mass range 0.6-1.8 GeV/c2. After correcting for unmeasured decay modes in this mass range, they obtain a branching fraction for b → d[gamma] of (7.2 ± 2.7(stat.) ± 2.3(syst.)) x 10−6. Taking the ratio of X{sub d} to X{sub s} they find [Lambda](b → d[gamma])/[Lambda](b → s[gamma]) = 0.033 ± 0.013(stat.) ± 0.009(syst.), from which they determine.
The photon spectrum in B 2!X{sub s}[gamma] decay, where X{sub s} is any strange hadronic state, is studied using a data sample of 88.5 x 106 ee− 2![Upsilon](4S) 2!B{bar B} decays collected by the BABAR experiment at SLAC. The partial branching fraction, [Delta][Beta](B 2!X{sub s}[gamma]) = (3.67 ± 0.29(stat.) ± 0.34(sys.) ± 0.29(model)) x 10−4, the first moment E{sub {gamma}} = 2.288 ± 0.025 ± 0.017 ± 0.015 GeV and the second moment E{sub {gamma}}2 = 0.0328 ± 0.0040 ± 0.0023 ± 0.0036 GeV2 are measured for the photon energy range 1.9 GeV E{sub {gamma}}
We present a measurement of the Cabibbo-Kobayashi-Maskawa CP-violating phase {gamma} with a Dalitz plot analysis of neutral D-meson decays to the K{sub S}{sup 0} {pi}{sup -}{pi}{sup +} final state from B{sup {-+}} {yields} D{sup (*)}K{sup {-+}} and B{sup {-+}} {yields} DK*{sup {-+}} decays, using a sample of 227 million B{bar B} pairs collected by the BABAR detector. We measure {gamma} = (67 {+-} 28 {+-} 13 {+-} 11){sup o}, where the first error is statistical, the second is the experimental systematic uncertainty and the third reflects the Dalitz model uncertainty. This result suffers from a two-fold ambiguity. The contribution to the Dalitz model uncertainty due to the description of the {pi}{pi} S-wave in D{sup 0} {yields} K{sub S}{sup 0}{pi}{sup -}{pi}{sup +}, evaluated using a K-matrix formalism, is found to be 3{sup o}.
Observational evidence and theoretical motivation have led us to the conclusion that our current understanding of the universe is incomplete. While new physics is expected to exist above the electroweak scale, its influence can be detected by experiments that operate below this scale. The Babar experiment has recorded approximately 432 fb-1 of data at the center of mass energy of 10.58 GeV, which corresponds to the Y(4S) mass. One of the physics programs is studying radiative decays of the B meson. These decays primarily proceed through loop diagrams, and thus influences of new particles may be detectable. In this thesis, I present results of the measurements of the branching fractions, CP asymmetry, and isospin asymmetry of B -> K* gamma. Results are also presented for the measurements of the branching fractions of B -> rho(omega) gamma. Finally, a search for the decay of B -> phi gamma is given.
We use 429 fb−1 of ee− collision data collected at the?(4S) resonance with the BABAR detector to measure the radiative transition rate of b → s? 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?({bar B} → Xs?) = (3.29 ± 0.19 ± 0.48) x 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, m{sub b} and?{sub {pi}}2, in the kinetic and shape function models.
The electromagnetic penguin process b [yields] s[gamma] is very interesting to theorists because it can be used to constrain contributions from new physics that could enter at the one loop level. The high statistics of B[bar B] events collected at the BABAR experiment make a measurement of this rare decay possible. The branching fraction of a sum of exclusive b [yields] s[gamma] decay modes is measured as a function of the strange hadronic mass. This is a large step toward the measurement of the b [yields] s[gamma] rate.