Studies ofB0−B0mixing properties with inclusive dilepton events

Abstract

We report a precise determination of the $B^0-B^0$ mixing parameter $\Delta m_d$ based on the time evolution of same-sign and opposite-sign dilepton yields in ${\rm Y}\mathrm{}\left(4S\right)\mathrm{}$ decays. Data were collected with the Belle detector at KEKB. Using data samples of 29.4 ${\mathrm{fb}}^{\mathrm{-}1}$ recorded at the ${\rm Y}\mathrm{}\left(4S\right)\mathrm{}$ resonance and 3.0 ${\mathrm{fb}}^{\mathrm{-}1}$ recorded at an energy 60 MeV below the resonance, we measure $\Delta m_d=[0.503\pm 0.008(\mathrm{stat})\pm 0.010(\mathrm{syst}\left)\right]{\mathrm{ps}}^{-1}.$ From the same analysis, we also measure the ratio of charged and neutral B meson production at the ${\rm Y}\mathrm{}\left(4S\right),$ $f_{+}{/f}_0=1.01\mathrm{}\pm 0.03\left(\mathrm{stat}\right)\pm 0.09\left(\mathrm{syst}\right),$ and CPT violation parameters in $B^0-B^0$ mixing, $\mathfrak{R}\left(\cos \theta \right)=0.00\mathrm{}\pm 0.12\left(\mathrm{stat}\right)\pm 0.01\left(\mathrm{syst}\right)$ and $\mathfrak{I}\left(\cos \theta \right)=0.03\mathrm{}\pm 0.01\left(\mathrm{stat}\right)\pm 0.03\left(\mathrm{syst}\right).\mathrm{}$