Pion Oscillations

Abstract

Pions produced via the $D^{+}\to {\pi }^{+}\overline{K^0}$ decay are in an entangled superposition of energy states because the $\overline{K^0}$ is not a mass eigenstate. This presents an opportunity to access kaon mixing parameters via $\pi$ decay accompanied by flavor tagged kaons. The pion oscillation frequency is $\Delta m_K\frac{m_K}{m_D}$, about 224 MHz. This method may help refine measurements of $\Delta m_{D^0}$ via $B^{+}\to {\pi }^{+}\overline{D^0}$.

Comments: The actual oscillation distance is the distance between the pion and the kaon mass eigenstate. This was not made clear in the article