Sensitivity targets for dark photon searches in charged kaon decays
We investigate the prospects for detecting invisible dark photons in charged kaon decays through the two-pion channel $K^+\to\pi^+\pi^0\,\gamma_D$ and the one-pion radiative decay $K^+\to\pi^+\gamma\,\gamma_D$, where $\gamma$ and $\gamma_D$ denote the ordinary photon and dark photon, respectively. The former decay was...