Effect of nuclear interactions of neutral kaons on $CP$ asymmetry measurements

We examine the effect of the difference in nuclear interactions of $K^0$ and ${\overline{K}}^0$ mesons on the measurement of $CP$ asymmetry for experiments at $e^{+}{e}^{-}$ colliders—charm and $B$-meson factories. We find that this effect on $CP$ asymmetry can be as large as 0.3%, and therefore sufficiently significant in interpreting measurements of $CP$ asymmetry when neutral kaons are present in the final state.

Figure 1

The $\Delta \sigma (K^{-}\{d,p\})=\sigma (K^{-}\{d,p\})-\sigma (K^{+}\{d,p\})$ values as a function of kaon momentum, obtained from [8] for the proton (dotted lines) and the deuteron data (solid) are shown in the top plot. The ratio of two cross section differences as a function of kaon momentum is shown in the bottom plot (solid circles), together with the fit using the error function (curve).

Figure 2

$K_S^0$ momentum (left column) and angular distributions (right column) for different decay modes. The upper two rows are for $\sqrt{s}=10.58\mathrm{GeV}$ and the $\beta \gamma =0.425$ configuration and the bottom row is for $\sqrt{s}=3770\mathrm{MeV}$.

Figure 3

Distributions of $A_{\mathcal{D}}$ as a function of $K_S^0$ momentum (left) and the polar angle (right) for $D^{+}\to K_S^0{\pi }^{+}$ for $\sqrt{s}=10.58\mathrm{GeV}$ and $\beta \gamma =0.425$ (top) and for $D^0\to K_S^0{\pi }^{+}{\pi }^{-}$ for $\sqrt{s}=3770\mathrm{GeV}$ configuration (bottom). Case I detector geometry is used in both instances.