Measurement of Branching Fractions of B Decays to K1(1270)pi and K1(1400)pi and Determination of the CKM Angle Alpha from B0 --] A1(1260) /- Pi- PDF Download

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Languages : en
Pages : 18

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We report measurements of the branching fractions of neutral and charged B meson decays to final states containing a K1(1270) or K1(1400) meson and a charged pion. The data, collected with the BABAR detector at the SLAC National Accelerator Laboratory, correspond to 454 million B{bar B} pairs produced in ee− annihilation. We measure the branching fractions?(B° → K1(1270)+?− + K1(1400)+?−) = 3.1{sub 0.7}{sup +0.8} x 10−5 and?(B+ → K1(1270)°?+ + K1(1400)°?+) = 2.9{sub -1.7}{sup +2.9} x 10−5 (

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Languages : en
Pages : 127

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In the Standard Model, CP violation in weak interactions involving quarks is parameterized by an irreducible complex phase in the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing-matrix. The precise determination of the CKM elements is a necessary ingredient for a stringent test of the Standard Model predictions, and is a crucial input for reducing the theoretical error in many New Physics searches with flavor, e.g., in the kaon sector. The unitarity of the CKM matrix is typically expressed as a triangle relationship among its parameters, where the area of the so-called Unitarity Triangle visually depicts the amount of asymmetry between the decays of B particles and their antimatter counterparts. In the past few years, the BABAR and Belle experiments have been able to measure all three angles of the triangle from CP asymmetry measurements. The first asymmetry measurements in B particle decays, about ten years ago, allowed to determine ?, which is now known to better than 5% precision. The angles ? and ?, measured in much rarer processes, required several years of data taking before analyses could yield reliable answers. A remarkable feature is that the direct measurement of the angles of the Unitarity Triangle generates an area that is consistent with the area predicted by measurement of the sides. In this thesis we have presented the branching fraction measurements of charged and neutral B meson decays to K1(1270)? and K1(1400)?, obtained from a data sample of 454 million ?(4S) → B$ar{B}$ events. This analysis is particularly challenging from the experimental side since the branching fractions involved are very low, at the level of 10-6 - 10-7, and the signal is characterized by the simultaneous presence of two overlapping resonances, which exhibit sizeable interference effects. The combined K1(1270)? and K1(1400)? signal is therefore modeled with a K-matrix formalism, which accounts for the effects of interference between the K1(1270) and K1(1400) mesons by introducing two effective parameters. The model is derived from the analysis, performed by the ACCMOR Collaboration, of the diffractive production of strange mesons.

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Languages : en
Pages : 16

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We present a measurement of the branching fraction of neutral B meson decaying to final states containing a K1 meson, i.e. K1(1270) and K1(1400), and a charged pion. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 454 million B{bar B} pairs produced in ee− annihilation. We measure the branching fraction?(B° → K1+?−) = (31.0 ± 2.7 ± 6.9) x 10−6, where the first error quoted is statistical and the second is systematic. In the framework of the K-matrix formalism used to describe these decays, we also set limits on the ratio of the production constants for the K1(1270)+ and K1(1400)+ mesons in B° decays.

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Languages : en
Pages : 8

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We study the decays B 2![eta]{sub c}K and B° 2![eta]{sub c}K°, where the [eta]{sub c} is reconstructed in the K{sub S}° K{sup ±} [pi]{sup {-+}} and K+K− [pi]° decay modes. Results are based on a sample of 86 million B{bar B} pairs collected with the BABAR detector at the SLAC e+e− B Factory. We measure the branching fractions [Beta](B+ 2![eta]{sub c}K+) = (1.34 ± 0.09 ± 0.13 ± 0.41) x 10−3 and [Beta](B° 2![eta]{sub c}K°) = (1.18 ± 0.16 ± 0.13 ± 0.37) x 10−3, where the first error is statistical, the second is systematic, and the third reflects the [eta]{sub c} branching fraction uncertainty. In addition, we search for B 2![eta]{sub c}K events with [eta]{sub c} 2!2(K+K−) and [eta]{sub c} 2![phi][phi] and determine the [eta]{sub c} decay branching fraction ratios [Beta]([eta]{sub c} 2!2(K+K−))/[Beta]([eta]{sub c} 2!K{bar K}[pi]) = (2.3 ± 0.7 ± 0.6) x 10−2 and [Beta]([eta]{sub c} 2![phi][phi])/[Beta]([eta]{sub c} 2!K{bar K}[pi]) = (5.5 ± 1.4 {+-} 0.5) x 10−2.

Author: Attila Mihalyi
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Languages : en
Pages : 198

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Author: Alexander Lenz
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Languages : en
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Languages : en
Pages : 11

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Using data taken with the CLEO II detector, we present the first full angular analysis in the color-suppressed modes B° 2!J/[psi] K*° and B 2!J/[psi] K*. This leads to a complete determination of the decay amplitudes of these modes. In addition, we update the branching fractions for B 2!J/[psi] K and B 2!J/[psi] K*.

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Languages : en
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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[Beta](B[yields] Xe[nu])= (10.87[+-] 0.18(stat)[+-] 0.30(syst))%. Based on this measurement we determine the CKM matrix elementV[sub cb].

Author: Alexander Lenz
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Languages : en
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Languages : en
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We use a global fit to determine the form factor slopes and branching fractions of the decays B --> Dlnu and B --> D*lnu. We reconstruct Dl pairs and construct a 3-dimensional distribution binned in lepton momentum, D momentum and cosTheta(B-Dl). These kinematic variables provide good separation between the signal and background. We fit electron and muon samples separately and combine them after calculating systematic uncertainties. The form factor slopes, rhoD^2 for B --> Dlnu and rho^2 for B --> D*lnu decays, are measured to be rhoD^2 = 1.22 +- 0.04 +- 0.07 and rho^2 = 1.21 +- 0.02 +- 0.07, where the errors are statistical and systematic, respectively. Branching fractions are fitted to be B(B+ --> D0lnu) = (2.36 +- 0.03 +- 0.12) % and B(B^+ --> D*0lnu) = (5.37 +- 0.02 +- 0.21) %. We use these results to determine the products, G(1)|Vcb| = (43.8 +- 0.8 +- 2.3)*10^{-3} and F(1)|Vcb| = (35.7 +- 0.2 +- 1.2)*10^{-3} of the form factors at zero recoil and the CKM matrix element |Vcb|, from which |Vcb| can be extracted using theoretical input.