Baryon-Antibaryon Contributions to theK20−K10Mass Difference in a Current-Current Quark Model

Abstract

The baryon-antibaryon contributions to the $K_2^0-K_1^0$ mass difference are studied in an extended fermion-loop model as a further consistency test of a current-current quark model. It is found that contributions arising from the parity-conserving weak Hamiltonian phenomenologically constructed of one-baryon octet matrix elements are negligible compared to the crude estimate of the $K_1^0$ mass shift, $\Delta \left(m_{K_1}^0\right)=-\left(\frac{\hslash }{2{\tau }_s}\right){cot\delta }_{00}\left({m_K}^2\right)$. Although the contribution to the $K_2^0$ mass shift arising from the parity-violating weak Hamiltonian via an $S$-wave effective meson-baryon-baryon interaction turns out to be comparable to $\Delta \left(m_{K_1}^0\right)$ and negative, the extended loop model is not incompatible with present theoretical understanding of the $K_2^0-K_1^0$ mass difference.