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<A NAME=MASS>

<TITLE>MASS</TITLE></A>
<b><a href=r37_idx.html>INDEX</a></b><p><p>



<B>MASS</B> _ _ _  _ _ _  _ _ _  _ _ _ <B>command</B><P>
<P>
 
The <em>mass</em> command associates a scalar variable as a mass with 
the corresponding vector variable, in high-energy physics calculations. 
 <P> <H3> 
syntax: </H3>
<P>
<P>
<em>mass</em>&lt;vector-var&gt;<em>=</em>&lt;scalar-var&gt; 
{,&lt;vector-var&gt;<em>=</em>&lt;scalar-var&gt;}* 
<P>
<P>
<P>
&lt;vector-var&gt; can be a declared vector variable; <em>mass</em> will declare
 
it to be of type <em>vector</em> if it is not. This may override an existing 
matrix variable by that name. &lt;scalar-var&gt; must be a scalar variable. 
<P>
<P>
 <P> <H3> 
examples: </H3>
<P><PRE><TT>
vector bb,cc; 

mass cc=m; 

mshell cc; 

cc.cc; 

   2
  M

</TT></PRE><P>Once a mass has been attached to a vector with a <em>mass</em> dec
laration, 
the 
<A HREF=r37_0414.html>mshell</A> declaration puts the associated particle ``on t
he mass 
shell.'' Subsequent scalar (.) products of the vector with itself will be 
replaced by the square of the mass expression. 
<P>
<P>
<P>