\begin{table} \centering \label{tab:LE_beams} % \caption[]{ Beam requirements for new muon experiments. Given are the necessary sign of charge $q_{\mu}$ and the minimum of the total muon number $\int I_{\mu}dt$ above which significant progress can be expected in the physical interpretation of the experiments. Measurements which require pulsed beams are sensitive to the muon suppression $I_0/I_{m}$ between pulses of length $\delta T$ and separation $\Delta T$. Most experiments require energies up to 4 MeV corresponding to 29 MeV/c momentum. Thin targets, respectively storage ring acceptances, demand rather small momentum bites $\Delta p_{\mu}/p_{\mu}$ \cite{Aysto_01}. } { % \begin{tabular}[hbt]{|c|c|c|c|c|c|c|c|} % \hline % &&&&&&&\\ % Experiment & $q_{\mu}$ &$\int I_{\mu}dt$&$I_0/I_{\mu}$&$\delta T$&$\Delta T$&$E_{\mu}$&$\Delta p_{\mu}/p_{\mu}$\\ & & & & [ns] & [ns] & [MeV] & [\%] \\ % \hline % $\mu^-N \rightarrow e^-N$ &-- &$10^{19}$&$<10^{-9}$&$\leq 100$&$\geq 1000$ &$<20$ &1...5 \\ $\mu \rightarrow e \gamma$ &+ &$10^{16}$& n/a &continuous &continuous &1...4 &1...5 \\ $\mu \rightarrow eee$ &+ &$10^{15}$& n/a &continuous &continuous &1...4 &1...5 \\ $\mu^+e^- \rightarrow \mu^-e^+$&+ &$10^{16}$&$<10^{-4}$&$<1000$s &$\geq 20000$ &1...4 &1...2 \\ % \hline % $\tau_{\mu}$ &+ &$10^{13}$&$<10^{-4}$&$<100 $ &$\geq 20000$ &4 &1...10 \\ $non (V-A)$ &$\pm$&$10^{13}$&$ n/a $ &continuous &continuous &4 &1...5 \\ % \hline % $g_{\mu}-2$ &$\pm$&$10^{15}$&$<10^{-7}$&$\leq 50 $ &$\geq 10^6$ &3100 &$10^{-4}$ \\ $edm_{\mu}$ &$\pm$&$10^{16}$&$<10^{-6}$&$\leq 50 $ &$\geq 10^6 $ &$\leq$1000&$\leq 10^{-5}$\\ % \hline % $M_{HFS}$ &+ &$10^{15}$&$<10^{-4}$&$\leq 1000$ &$\geq 20000$ &4 &1...3 \\ $M_{1s2s}$ &+ &$10^{14}$&$<10^{-3}$&$\leq 500 $ &$\geq 10^6$ &1...4 &1...2 \\ % \hline % $\mu^- atoms$ &-- &$10^{14}$&$<10^{-3}$&$\leq 500 $&$\geq 20000$ &1...4 &1...5 \\ % \hline % $condensed$ $matter$ &$\pm$&$10^{14}$&$<10^{-3}$&$< 50 $ &$\geq 20000$ &1...4 &1...5 \\ $(incl.$$bio$ $ sciences)$ &&&&&&&\\ % \hline % KJ 14 Nov 2000 \end{tabular} } \end{table} % The current status and prospects for advances in these areas are included in Table~\ref{tab:LEexpts}, which list present efforts in the field and prospected improvements at a neutrino factory or muon collider facility. The beam parameters necessary for the expected improvements are listed in Table~\ref{tab:LE_beams} It is worth recalling that LFV as a manifestation of neutrino mixing is suppressed as $(\delta m^2)^2/m_W^4$ and is thus entirely negligible. However, a variety of new-physics scenarios predict observable effects. Table~\ref{tab:newmuphys} lists some examples of limits on new physics that would be implied by nonobservation of $\mu$-to-$e$ conversion ($\mu^-N\to e^-N$) at the $10^{-16}$ level~\cite{Marciano97}. \begin{table} \caption[New physics probed by $\mu\rightarrow e$ experiments] {Some examples of new physics probed by the nonobservation of $\mu\rightarrow e$ conversion at the $10^{-16}$ level (from~\protect\cite{Marciano97}).\label{tab:newmuphys}} \begin{center} \begin{tabular}{|lc|} \hline New Physics & Limit \\ \hline Heavy neutrino mixing & $|V_{\mu N}^*V_{e N}|^2<10^{-12}$\\ Induced $Z\mu e$ coupling & $g_{Z_{\mu e}}<10^{-8}$\\ Induced $H\mu e$ coupling & $g_{H_{\mu e}}<4\times10^{-8}$\\ Compositeness & $\Lambda_c>3,000\,$TeV\\ \hline \end{tabular} \end{center} \end{table}