Precise measurement of the CP violation parameter sin2phi_1 in B0-->(cbar c)K0 decays

We present a precise measurement of the CP violation parameter sin2phi_1 and the direct CP violation parameter A_f using the final data sample of 772x10^6 Bbar B pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. One neutral B meson is reconstructed in a J/psi K0S, psi(2S) K0S, chi_c1 K0S or J/psi K0L CP-eigenstate and its flavor is identified from the decay products of the accompanying B meson. From the distribution of proper time intervals between the two B decays, we obtain the following CP violation parameters: sin2phi_1=0.667+-0.023(stat)+-0.012(syst) and A_f=0.006+-0.016(stat)+-0.012(syst).

Measurement of the form factors of the decay B^0 -> D^{*-} l^+ nu_l and determination of the CKM matrix element |V_{cb}|

This paper describes a determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ using the decay $B^0to D^{*-}ell^+ u_ell$. We perform a combined measurement of this quantity and of the form factors $rho^2$, $R_1(1)$, and $R_2(1)$ which fully characterize this decay in the framework of heavy-quark effective theory, based on 140 fb$^{-1}$ of Belle data collected near the $Upsilon(4S)$ resonance. The results, based on about 69,000 reconstructed $B^0to D^{*-}ell^+ u_ell$ decays, are $rho^2=1.293pm 0.045pm 0.029$, $R_1(1)=1.495pm 0.050pm 0.062$, $R_2(1)=0.844pm 0.034pm 0.019$ and $mathcal{F}(1)|V_{cb}|=34.4pm 0.2pm 1.0$. The $B^0to D^{*-}ell^+ u_ell$ branching fraction is found to be $(4.42pm 0.03pm 0.25)%$. For all these numbers, the first error is the statistical and the second is the systematic uncertainty. All results are preliminary.