Quark model relation for kaon charge radii

We derive the equation r_E²(K⁰)/r_E²(K⁺) = m_s² − m_n²))/(2m_s² + m_n²) relating the kaon electric charge radii and the strange (m_s) and non-strange (m_n) quark masses in the nonrelativistic quark model, and suggest an inequality which we expect to hold in the presence of relativistic corrections. New data for these charge radii are presently being analysed by two experimental groups.