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To drop fermion's mass safely

It is safe if we drop fermion's mass in the numinator of amplitude square and keep it in the denominator. To do it, the user can add the following table to the input file "process.def":


\begin{picture}(490,120)
\put(230,60){\oval(480,120)}
\put(0,60){
\begin{tabula...
...rop\_list:='(& \\
&(fme 0) \\
&...... \\
&);
\end{tabular}}
\end{picture}

where the first line means to drop electron's mass in numinator of amplitude square. It is easy to add more line to drop mass of other fermion.



wang jian xiong 2003-01-10