A completely relativistic quark model in the Bethe-Salpeter framework is employed to calculate the exclusive production ratio of the neutral to charged kaon pair in $e^{+}{e}^{-}$ annihilation continuum region below the $J/\mathrm{\Psi }$ mass. The valence quark charge plays the key role. The cancellation of the diagrams for the same charge case ($K_S+K_L$) and the noncancellation of the diagrams for the different charge case ($K^{-}+K^{+}$) lead to the ratio as ${(m_s-m_d)}^2/M_{kaon}^2\approx 1/10$.

• Received 20 August 2019
• Revised 18 February 2020
• Accepted 6 April 2020

DOI:https://doi.org/10.1103/PhysRevC.102.015201

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society