Read and Download eBook Full
Author: Alexei Volk
Publisher:
Published: 2009
Total Pages: 127
ISBN-13:
DOWNLOAD EBOOKAuthor: Alexei Volk
Publisher:
Published: 2009
Total Pages: 127
ISBN-13:
DOWNLOAD EBOOKAuthor:
Publisher:
Published: 2009
Total Pages:
ISBN-13:
DOWNLOAD EBOOKThis thesis presents an analysis of inclusive semileptonic $B \to X_u e \nu$ decays using approximately 454 million $\Upsilon(4S) \to B \bar{B}$ decays collected during the years 1999 to 2008 with the BABAR detector. The electron energy, $E_e$, and the invariant mass squared of the electron-neutrino pair, $ q^2$, are reconstructed, where the neutrino kinematics is deduced from the decay products of both B mesons. The final hadronic state, $ X_u$, consists of a sum of many hadronic channels, each of which contains at least one $u$ quark. The variables $q^2$ and $E_e$ are then combined to compute the maximum kinematically allowed invariant mass squared of the hadronic system, $s_h^{max}$. Using these kinematic quantities, the partial branching fraction, $\Delta BR(B \to X_u e \nu)$, unfolded for detector effects, is measured to be $\Delta BR(E_e>2.0 GeV, s_h^{max}3.52 GeV^2) = (3.33 \pm 0.18 \pm 0.21) \times 10^{-4} in the $\Upsilon(4S)$ and \Delta \tilde{\BR}(\tilde E_e1.9 GeV, \tilde {s}^{max}_{h}
Author:
Publisher:
Published: 2002
Total Pages: 9
ISBN-13:
DOWNLOAD EBOOKA 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 → Xe[nu]) = (10.87 ± 0.18(stat) ± 0.30(syst))%. Based on this measurement we determine the CKM matrix element.
Author:
Publisher:
Published: 2005
Total Pages: 19
ISBN-13:
DOWNLOAD EBOOKCharmless 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.
Author:
Publisher:
Published: 2004
Total Pages:
ISBN-13:
DOWNLOAD EBOOKWe determine the inclusive B [yields] X[sub c][ell][nu] branching fraction, [Beta][sub c[ell][nu]], the CKM matrix element V[sub cb], and other heavy-quark parameters from a simultaneous fit to moments of the hadronic-mass and lepton-energy distributions in semileptonic B-meson decays, measured as a function of the lower limit on the lepton energy, using data recorded with the BABAR detector. Using Heavy Quark Expansions (HQEs) to order 1/m[sub b][sup 3], we extract [Beta][sub ce[nu]] = (10.61 [+-] 0.16[sub exp] [+-] 0.06[sub HQE])% and V[sub cb] = (41.4 [+-] 0.4[sub exp] [+-] 0.4[sub HQE] [+-] 0.6[sub th]) x 10[sup -3]. The stated errors refer to the experimental, HQE, and additional theoretical uncertainties.
Author:
Publisher:
Published: 2003
Total Pages: 7
ISBN-13:
DOWNLOAD EBOOKWe report a measurement of the inclusive charmless semileptonic branching fraction of B mesons in a sample of 89 million B{bar B} events recorded with the BABAR detector at the [Upsilon](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. The number of signal events is extracted from the hadronic mass distribution and is used to determine the ratio of branching fractions [Beta]({bar B} → X{sub u}l{bar {nu}})/[Beta]({bar B} → Xl{bar {nu}}) = (2.06 ± 0.25(stat) ± 0.23(syst) ± 0.36(theo)) x 10−2. Using the measured branching fraction for inclusive semileptonic B decays, we find [Beta]({bar B} → X{sub u}l{bar {nu}}) = (2.24 ± 0.27(stat) ± 0.26(syst) ± 0.39(theo)) x 10−3 and derive the CKM matrix element.
Author: Nicola Gagliardi
Publisher:
Published: 2009
Total Pages:
ISBN-13:
DOWNLOAD EBOOKAuthor:
Publisher:
Published: 2004
Total Pages:
ISBN-13:
DOWNLOAD EBOOKThe BABAR experiment at SLAC provides an opportunity for measurement of the Standard Model parameters describing CP violation. A method of measuring the CKM matrix element V[sub cb] using Inclusive Semileptonic B decays in events tagged by a fully reconstructed decay of one of the B mesons is presented here. This mode is considered to be one of the most powerful approaches due to its large branching fraction, simplicity of the theoretical description and very clean experimental signatures. Using fully reconstructed B mesons to flag B[bar B] event we were able to produce the spectrum and branching fraction for electron momenta P[sub C.M.S.]> 0.5 GeV/c. Extrapolation to the lower momenta has been carried out with Heavy Quark Effective Theory. The branching fractions are measured separately for charged and neutral B mesons. For 82 fb[sup -1] of data collected at BABAR we obtain: BR(B[sup [+-]] [yields] X e[bar [nu]]) = 10.63 [+-] 0.24 [+-] 0.29%, BR(B[sup 0] [yields] X e[bar [nu]]) = 10.68 [+-] 0.34 [+-] 0.31%, averaged BR(B [yields] X e[bar [nu]]) = 10.65 [+-] 0.19 [+-] 0.27%, ratio of Branching fractions BR(B[sup [+-]])/BR(B[sup 0]) = 0.996 [+-] 0.039 [+-] 0.015 (errors are statistical and systematic, respectively). They also obtain V[sub cb] = 0.0409 [+-] 0.00074 [+-] 0.0010 [+-] 0.000858 (errors are: statistical, systematic and theoretical).
Author:
Publisher:
Published: 2011
Total Pages: 8
ISBN-13:
DOWNLOAD EBOOKThe authors present measurements of partial branching fractions of B 2!KX, B 2!K° X, and B 2![pi]+X, where X denotes any accessible final state above the endpoint for B decays to charmed mesons, specifically for momenta of the candidate hadron greater than 2.34 (2.36) GeV for kaons (pions) in the B rest frame. These measurements are sensitive to potential new-phisics particles which could enter the b 2!s(d) loop transitions. The analysis is performed on a data sample consisting of 383 x 106 B{bar B} pairs collected with the BABAR detector at the PEP-II e+e− asymmetric energy collider. The results are in agreement with standard model predictions and exclude large enhancements of the inclusive branching fraction due to sources of new physics.
