Measurement of theCPViolation Parametersin2φ1inBd0Meson Decays

We present a measurement of the standard model $\mathrm{CP}$ violation parameter $\mathrm{sin}2{\ensuremath{\varphi}}_{1}$ (also known as $\mathrm{sin}2\ensuremath{\beta}$) based on a $10.5{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB asymmetric ${e}^{+}{e}^{\ensuremath{-}}$ collider. One neutral $B$ meson is reconstructed in the $J/\ensuremath{\psi}{K}_{S}$, $\ensuremath{\psi}(2S){K}_{S}$, ${\ensuremath{\chi}}_{c1}{K}_{S}$, ${\ensuremath{\eta}}_{c}{K}_{S}$, $J/\ensuremath{\psi}{K}_{L}$, or $J/\ensuremath{\psi}{\ensuremath{\pi}}^{0}$ $\mathrm{CP}$-eigenstate decay channel and the flavor of the accompanying $B$ meson is identified from its charged particle decay products. From the asymmetry in the distribution of the time interval between the two $B$-meson decay points, we determine $\mathrm{sin}2{\ensuremath{\varphi}}_{1}{\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.58}_{\ensuremath{-}0.34}^{+0.32}(\mathrm{stat}{)}_{\ensuremath{-}0.10}^{+0.09}(\mathrm{syst})$.