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Register a new user|q/p| Measurement from B0->D*l nu Partial Reconstruction
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We present a new measurement of CP violation induced by B0 B0bar oscillations, based on the full data set collected by the BaBar experiment at the PEPII collider. We use a sample of about 6 million B0->D* l nu decays selected with partial reconstruction of the D* meson. The charged lepton identifies the flavor of the first B meson at its decay time, the flavor of the other B is determined by kaon tagging. We determine the parameter dCP = 1 - |q/p| = (0.29+-0.84+1.78/-1.61) 10^-3.
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We report a study of semileptonic B decays to P-wave D** mesons. Semileptonic decay to D*_2 meson is observed for the first time and its product branching ratio is measured to be Br(B+ -> anti-D*0_2 l+nu) x Br(anti-D*0_2 -> D- pi+) = 0.22 +- 0.03(stat.) +- 0.04(syst.)%. The result is obtained using the fully reconstructed B tags from a data sample that contains 657 millions BB-bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider.
We report on a measurement of the branching fractions for B- --> D(*)+ pi- l- nu-bar and B0bar --> D(*)0 pi+ l- nu-bar with 275 million BBbar events collected at the Upsilon(4S) resonance with the Belle detector at KEKB. Events are tagged by fully reconstructing one of the B mesons in hadronic modes. We obtain Br(B- --> D+ pi- l- nu-bar) = (0.54 +/- 0.07(stat) +/- 0.07(syst) +/- 0.06(BR)) x 10^-2, Br(B- --> D*+ pi- l- nu-bar) = (0.67 +/- 0.11(stat) +/- 0.09(syst) +/- 0.03(BR)) x 10^-2, Br(B0bar --> D0 pi+ l- nu-bar) = (0.33 +/- 0.06(stat) +/- 0.06(syst) +/- 0.03(BR)) x 10^-2, Br(B0bar --> D*0 pi+ l- nu-bar) = (0.65 +/- 0.12(stat) +/- 0.08(syst) +/- 0.05(BR)) x 10^-2, where the third error comes from the error on Bbar --> D(*) l- nu-bar decays. Contributions from B0bar --> D*+ l- nu-bar decays are excluded in the measurement of B0bar --> D0 pi+ l- nu-bar.
The oscillation frequency Delta-md of B0 anti-B0 mixing is measured using the partially reconstructed semileptonic decay anti-B0 -> l- nubar D*+ X. The data sample was collected with the CDF detector at the Fermilab Tevatron collider during 1992 - 1995 by triggering on the existence of two lepton candidates in an event, and corresponds to about 110 pb-1 of pbar p collisions at sqrt(s) = 1.8 TeV. We estimate the proper decay time of the anti-B0 meson from the measured decay length and reconstructed momentum of the l- D*+ system. The charge of the lepton in the final state identifies the flavor of the anti-B0 meson at its decay. The second lepton in the event is used to infer the flavor of the anti-B0 meson at production. We measure the oscillation frequency to be Delta-md = 0.516 +/- 0.099 +0.029 -0.035 ps-1, where the first uncertainty is statistical and the second is systematic.
This article describes a determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ from the decay $B^0to D^{*-}ell^+ u_ell$ using 711 fb$^{-1}$ of Belle data collected near the $Upsilon(4S)$ resonance. We simultaneously measure the product of the form factor normalization $mathcal{F}(1)$ and the matrix element $|V_{cb}|$ as well as the three parameters $rho^2$, $R_1(1)$ and $R_2(1)$, which determine the form factors of this decay in the framework of the Heavy Quark Effective Theory. The results, based on about 120,000 reconstructed $B^0to D^{*-}ell^+ u_ell$ decays, are $rho^2=1.214pm 0.034pm 0.009$, $R_1(1)=1.401pm 0.034pm 0.018$, $R_2(1)=0.864pm 0.024pm 0.008$ and $mathcal{F}(1)|V_{cb}|=(34.6pm 0.2pm 1.0)times 10^{-3}$. The branching fraction of $B^0to D^{*-}ell^+ u_ell$ is measured at the same time; we obtain a value of $mathcal{B}(B^0 to D^{*-}ell^+ u_ell) = (4.58 pm 0.03 pm 0.26) %$. The errors correspond to the statistical and systematic uncertainties. These results give the most precise determination of the form factor parameters and $mathcal{F}(1)|V_{cb}|$ to date. In addition, a direct, model-independent determination of the form factor shapes has been carried out.
The decay B0 -> D K*0 and the charge conjugate mode are studied using 1.0fb-1 of pp collision data collected by the LHCb experiment at sqrt(s) = 7TeV in 2011. The CP asymmetry between the B0 -> D K*0 and the B0bar -> D K*0bar decay rates, with the neutral D meson in the CP-even final state K+K-, is found to be A_d_KK = -0.45 +- 0.23 +- 0.02, where the first uncertainty is statistical and the second is systematic. In addition, favoured B0 -> D K*0 decays are reconstructed with the D meson in the non-CP eigenstate K+ pi-. The ratio of the B-flavour averaged decay rates in D decays to CP and non-CP eigenstates is measured to be R_d_KK = 1.36 (+0.37) (-0.32) +- 0.07, where the ratio of the branching fractions of D0 -> K- pi+ to D0 -> K+ K- decays is included as multiplicative factor. The CP asymmetries measured with two control channels, the favoured B0 -> DK*0 decay with D -> K+ pi- and the Bs0bar -> D K*0 decay with D K+ K-, are also reported.
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