coming 
beam particles. One is to use the <code>init()</code> method with no 
arguments. Then the settings variables below will be read and used. The 
alternative is to call <code><a href="ProgramFlow.html" target="page">init(...)</a></code> 
with arguments that provide this information. Then you need not use the 
variables below (although it would still be possible). Note that, if nothing 
is done, you will default to LHC at 14 TeV.

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Currently the beam particles must be either a hadron pair or a lepto