We report the first measurement of the lepton forward-backward asymmetry ${cal A}_{rm FB}$ as a function of the squared four-momentum of the dilepton system, $q^2$, for the electroweak penguin process $B rightarrow X_s ell^+ ell^-$ with a sum of excl
usive final states, where $ell$ is an electron or a muon and $X_s$ is a hadronic recoil system with an $s$ quark. The results are based on a data sample containing $772times10^6$ $Bbar{B}$ pairs recorded at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB $e^+ e^-$ collider. ${cal A}_{rm FB}$ for the inclusive $B rightarrow X_s ell^+ ell^-$ is extrapolated from the sum of 10 exclusive $X_s$ states whose invariant mass is less than 2 GeV/$c^2$. For $q^2 > 10.2$ GeV$^2$/$c^2$, ${cal A}_{rm FB} < 0$ is excluded at the 2.3$sigma$ level, where $sigma$ is the standard deviation. For $q^2 < 4.3$ GeV$^2$/$c^2$, the result is within 1.8$sigma$ of the Standard Model theoretical expectation.
We report a measurement of the CP-violation parameter sin2$phi_1$ at the $Upsilon(5S)$ resonance using a new tagging method, called $B$-$pi$ tagging. In $Upsilon(5S)$ decays containing a neutral $B$ meson, a charged $B$, and a charged pion, the neutr
al $B$ is reconstructed in the $J/psi K_S^0$ CP-eigenstate decay channel. The initial flavor of the neutral $B$ meson at the moment of the $Upsilon(5S)$ decay is opposite to that of the charged $B$ and may thus be inferred from the charge of the pion without reconstructing the charged $B$. From the asymmetry between $B$-$pi^+$ and $B$-$pi^-$ tagged $J/psi K_S^0$ yields, we determine sin2$phi_1$ = 0.57 $pm$ 0.58(stat) $pm$ 0.06(syst). The results are based on 121 fb$^{-1}$ of data recorded by the Belle detector at the KEKB $e^+ e^-$ collider.
