Bounds on the $\mathit{CP}$ Asymmetry in Like-Sign Dileptons from ${\mathit{B}}^0{\overline{B}}^0$ Meson Decays

We have measured the charge asymmetry in like-sign dilepton yields from $B^0{\overline{B}}^0$ meson decays using the CLEO detector at the Cornell Electron Storage Ring. We find $a_{\ell \ell }^0\equiv \left[N\right({\ell }^{+}{\ell }^{+})-N({\ell }^{-}{\ell }^{-}\left)\right]/\left[N\right({\ell }^{+}{\ell }^{+})+N({\ell }^{-}{\ell }^{-}\left)\right]=+0.013\mathrm{}\pm 0.050\pm 0.005$. We combine this result with a previous, independent measurement and obtain $\mathrm{Re}\left({\epsilon }_B\right)/(1+|{\epsilon }_B{|}^2)=+0.0035\mathrm{}\pm 0.0103\pm 0.0015$ (uncertainties are statistical and systematic, respectively) for the $\mathrm{CP}$ impurity parameter, ${\epsilon }_B$.