Search results for "B MESON"
showing 6 items of 246 documents
Measurement of the lifetime difference in the B$_s^0$ system
2005
We present a study of the decay B_s^0 -> J/psi phi We obtain the CP-odd fraction in the final state at time zero, R_perp = 0.16 +/- 0.10 (stat) +/- 0.02 (syst), the average lifetime of the (B_s, B_sbar) system, tau (B_s^0) =1.39^{+0.13}_{-0.16} (stat) ^{+0.01}_{-0.02} (syst) ps, and the relative width difference between the heavy and light mass eigenstates, Delta Gamma/Gamma = (Gamma_L - Gamma_H)/Gamma =0.24^{+0.28}_{-0.38} (stat) ^{+0.03}_{-0.04} (syst). With the additional constraint from the world average of the B_s^0$lifetime measurements using semileptonic decays, we find tau (B_s^0)= 1.39 +/- 0.06 ~ps and Delta Gamma/\Gamma = 0.25^{+0.14}_{-0.15}. For the ratio of the B_s^0 and B^0 li…
Note on the slope parameter of the baryonic Λb→Λc Isgur–Wise function
2005
Abstract Using the framework of the Heavy Quark Effective Theory we have re-analyzed the Isgur–Wise function describing semileptonic Λ b → Λ c decays in the QCD sum rule approach. The slope parameter of the Isgur–Wise function is found to be ρ 2 = 1.35 ± 0.13 , which is consistent with an experimental measurement and a lattice calculation. To O ( 1 / m b , 1 / m c ) of the heavy quark expansion the integrated Λ b decay width is used to extract the CKM matrix element V c b for which we obtain a value of | V c b | = 0.041 ± 0.004 ± 0.001 in excellent agreement with the value of | V c b | determined from semileptonic B → D ∗ decays.
The Isgur-Wise function from the lattice
1995
We calculate the Isgur-Wise function by measuring the elastic scattering amplitude of a $D$ meson in the quenched approximation on a $24^3\times48$ lattice at $\beta=6.2$, using an $O(a)$-improved fermion action. Fitting the resulting chirally-extrapolated Isgur-Wise function to Stech's relativistic-oscillator parametrization, we obtain a slope parameter $\rho^2=1.2+7-3. We then use this result, in conjunction with heavy-quark symmetry, to extract $V_{cb}$\ from the experimentally measured $\bar B\to D^*l\bar\nu\,$\ differential decay width. We find $|V_{cb}|\sqrt{\tau_B/1.48{\mathrm ps}}= 0.038 +2-2 +8-3, where the first set of errors is due to experimental uncertainties, while the second …
Measurements of Branching Fractions andCP-Violating Asymmetries inBMeson Decays to Charmless Two-Body States Containing aK0
2003
We present measurements of branching fractions and \CP-violating asymmetries in decays of $B$ mesons to two-body final states containing a \Kz. The results are based on a data sample of approximately 88 million \upsbb decays collected with the \babar detector at the \pep2 asymmetric-energy $B$ Factory at SLAC. We measure $\BR(\Bp\to\Kz\pip) = (22.3 \pm 1.7 \pm 1.1)\times 10^{-6}$, $\BR(\Bz\to\Kz\piz) = (11.4\pm 1.7\pm 0.8)\times 10^{-6}$, $\BR(\Bp\to\Kzb\Kp) < 2.5\times 10^{-6}$, and $\BR(\Bz\to\KzKzb) < 1.8\times 10^{-6}$, where the first uncertainty is statistical and the second is systematic, and the upper limits are at the 90% confidence level. In addition, the following \CP-violating a…
Search for anomalous top-quark couplings with the D0 detector
2008
Anomalous Wtb couplings modify the angular correlations of the top quark decay products and change the single top quark production cross section. We present limits on anomalous top quark couplings by combining information from W boson helicity measurements in top quark decays and anomalous coupling searches in the single top quark final state. We set limits on right-handed vector couplings as well as left-handed and right-handed tensor couplings based on about 1fb^-1 of data collected by the D0 experiment.
Evaluation of the flavor-changing vertexb→s+Husing the Breitenlohner-Maison-'t Hooft-Veltmanγ5scheme
1990
We reevaluate the one-loop-induced flavor-changing vertex {ital b}(bottom){r arrow}{ital s}(strange)+{ital H}(Higgs boson) using the Breitenlohner--Maison--'t Hooft--Veltman {gamma}{sub 5} scheme. Our result agrees with the result of previous calculations that employed a naive anticommuting {gamma}{sub 5} if one consistently employs left-chiral fermion fields in the perturbation expansion.