or $B$ mesons. Yet, what one does is the following: think of the $DN$ interaction for instance. In the $D^0 \, p \to D^0 \, p$ transition we have $c \bar u$ in the $D^0$ and $u u d$ quarks in the $p$, then we can only exchange $\rho^0$, $\omega$ vector mesons and the $c$ quark of the $D^0$ is a spectator. In this case the situation is the same as in $\bar{K}^0 \, p \to \bar{K}^0 \, p$. The $s$ quark of the $\bar{K}^0$ ($s \bar d \,$) is also a spectator and only $\rho$, $\omega$ vector mesons are exchanged. In as much as the $c$ quark in $D^0 \, p \to D^0 \, p$ is a spectator, the dynamics is the same as in the $\bar{K}^0 \, p \to \bar{K}^0 \, p$ transition, and for this we can use the local hidden gauge approach. We find thus a way to obtain the $D^0 \, p \to D^0 \, p$ interaction using the dynamics of the light quark sector, since only these quarks are also involved in this case. Hence, in the diagonal channels the interaction is well controlled.

However, assume the coupled channel $\pi \, \Sigma_c$, then in 