Detailed Description

Interface to Pythia 8.

StarPythia8 provides the user interface to the Pythia 8 event generator. To configure pythia8 for a specific run, users are encouraged to consult the Pythia 8 manual: http://home.thep.lu.se/~torbjorn/pythia81html/Welcome.html. In particular the section on the settings scheme http://home.thep.lu.se/~torbjorn/pythia81html/SettingsScheme.html.

The StarPythia8::Set() method passes configuration strings to the instance of pythia, as described under the "Operation" heading.

Configuration of the beam parameters (energy, frame, species, etc...) is through methods defined on the StarGenerator base class.

Code snippet illustrating how to setup pythia8 for W production at sqrt(s)=510 GeV

StarPythia8 *pythia8 = new StarPythia8();    
{
   pythia8->SetFrame("CMS", 510.0);
   pythia8->SetBlue("proton");
   pythia8->SetYell("proton");
   
   pythia8->Set("WeakSingleBoson:all=off");
   pythia8->Set("WeakSingleBoson:ffbar2W=on");
   pythia8->Set("24:onMode=0");              // switch off all W+/- decaus
   pythia8->Set("24:onIfAny 11 -11");        // switch on for decays to e+/-
   
}
primary -> AddGenerator( pythia8 );  

The general way that you configure Pythia8 is by passing a string to the generator which follows the form

System:Flag = value1 ... valueN

StarPythia8 (which is what the pythia8 variable points to in the example macro) passes these flags to Pythia8 using the Set method. So in general, you'll be calling it like

 pythia8 -> Set( "System:Flag = value1 ... valueN" )

 [ FYI -- The Set method really is just a wrapper to the Pythia8::Pythia::readString( string ) method.  ]

So then you need to figure out what the flags are you want to set. These are documented in the Pythia8 manual.

For example, you go to the manual and follow the link that says "QCD" under "Process Selection"... http://home.thep.lu.se/~torbjorn/pythia81html/QCDProcesses.html

You see a flag under "Hard QCD" processes, which is something which would be useful for jet production.

 flag  HardQCD:all   (default = off)
 Common switch for the group of all hard QCD processes, as listed separately in the following.

To set this parameter in the simulation, yould would call the Set method with

 pythia8 -> Set( "HardQCD:all = on" );

Author: Jason C. Webb

The documentation for this class was generated from the following file:

StarGenerator/Pythia8_1_62/StarPythia8.h