Proposed method for laser spectroscopy of pionic helium atoms to determine the charged-pion mass

Masaki Hori, Anna Sótér, Vladimir I. Korobov

Metastable pionic helium ($\pi {\mathrm{He}}^{+}$) is a three-body atom composed of a helium nucleus, an electron occupying the $1s$ ground state, and a negatively charged pion ${\pi }^{-}$ in a Ry…