is worth noting that contributions to $\mu \to e \gamma$ also arise from the $e_i \tilde W^+$ term in Eq. (\[L.n\]). However, this is further suppressed due to the $\tilde W^+$-charged lepton mixing, which is proportional to lepton masses. See the approximate value in Eq. (\[eq:wino.mixing\]).

Using Eq. (\[lambda2\]), the decay width of the stop LSP into a bottom quark and a charged lepton (henceforth, referred to as a bottom–charged lepton) is given by $$\begin{aligned}
    \label{x.width}
    \Gamma_{\tilde t_1 \to b \ell^+_i} & \sim \frac{1}{16 \pi}Y_b^2 \left| \frac{\epsilon_i}{\mu} \right|^2 m_{\tilde t_1},\end{aligned}$$ where $\tilde t_1$ indicates the lightest of the two physical stop states (SUSY mass eigenstates are typically numbered from lightest to heaviest). While this neglects order one factors and the contributions from ${v_L}_i$, it is useful for getting an impression of how the stop lifetime depends on the strength of $R$-parity violation. At any rate, it will be shown later that $\epsilon_i$ is typically larger than ${v_L}_i$. An order of magnitude approximation for the lifetime can be simply attained from the largest $\epsilon_i$ value, denoted $\epsilon_\text{max}$, by $$\tau_{\tilde t_1} \sim 1\times 10^{-14} \left( \frac{\epsilon_\text{max}/\mu}{10^{-5}}\right)^{-2} \left(\frac{100}{1+\tan^2 \beta} \right) \left(\frac{500 \text{ GeV}}{m_{\tilde t_1}} \right) \text{seconds}.$$ Taking representative values of $\mu, m_{\tilde t_1} 