How to generate data-like events

It's easy to generate a sample of events which represent data. Several generators can be used (Pythia, Herwig, Isajet) to generate the process of interest. You just need to run the cdfSim executable with an appropriate directives file. Instructions for changing the directives file (here, the Pythia generator is used as an example) are given below.

How to generate events

A sample directives file can be seen in /cdf/disk1/utilities/pythia_zmumu.tcl . This file generates Z->mumu decays. Copy this and change it however you want. The relevant parts that control particle generation are shown below: 

mod talk Pythia
  call_qq set t
  output set HEPG
  MSEL set 0
  commonMenu 
    for {set i 1} {$i<100} {incr i} {
      set_msub -index=$i -value=0
    }
    # Produce Zs only
    set_msub -index=15 -value=1
    set_msub -index=19 -value=0
    set_msub -index=30 -value=0
    show_msub
    # Z->mu mu only
    set_mstp -index=43 -value=2
    show_mstp
    for {set i 174} {$i<190} {incr i} {
      set_mdme -channelIndex=$i -decayType=0
    }
    set_mdme -channelIndex=184 -decayType=1
  exit
exit
Here we explicitly set the processes that (1) produce Z bosons, and (2) only allow the Z bosons to decay to muon pairs. A full description of all these switches can be found in the Pythia manual (see Useful Links below). In this example, MSEL (which can be used to set the flavour of the initial quarks) is turned off. We turn on Z production inside the commonMenu submenu, by setting the set_msub flags. The allowed Z decays are specified by the set_mdme flags.

How to run the job

Just type executable_path tcl_path , where executable_path is the full path to your cdfSim executable, and tcl_path is the full path to your directives file. Make sure that you have set the name of your output file and the number of events you want to generate in your directives file: 
talk DHOutput
  output create gen_stream pythia_zmumu_3_17_0int2.gen
... you will produce a file called pythia_zmumu_3_17_0int2.gen 

begin -nev 5000
.... with 5000 events in.

Useful links