Baur Monte Carlo Interface for Wgamma Event Generation

Baur's Monte Carlo package for simulating W+ gamma production at hadron colliders provides full electroweak calculation upto O(alpha) and contains higher order QCD corrections as well.

This page provides a description to generate events using the BaurMCInterface package.

The Baur MC documentation

"QCD Corrections to hadronic Wgamma production with nonstandard WWgamma couplings" U Baur, T Han, J Ohnemus Phys Rev D, vol. 48 #1, December 1993

Implementation of the package to generate Wgamma events using the Baur MC package

For CMSSW_1_6_X

The Baur MC package contains two disctinct parts: * The Baur MC generator which reads user-provided datacards and generates W(l,nu)gamma events and writes the four-vector of the final states in an ascii format. * The BaurWgamInterface package which interfaces the Baur MC generator with Pythia6 for hadronization and showering

To generate events, one has first to link the relevant libraries and compile the Baur MC generator to produce the hard-scattering part of the event, namely the qq'Bar -> W(->l, nu)gamma. The four-vectors of the final state lepton, the neutrion and the photon as well as the charge of the W for each event is written to an ascii file.

For a full description of the event and to get the output in the HepMC class format, one then has to link the ascii file to a Pythia6 generator which takes care of the subsequent soft interactions between the left-over partons from the two incoming protons. This is done by cheking out the GeneratorInterface/BaurWgamInterface package, compiling it and setting appropriate values for Pythia variables, lepton charge, leptoon generation through a configuration file.

How to compile the interface

cd <yourWorkingDirectoryUnderLxplus>
cp -p /afs/cern.ch/user/d/devdatta/public/baurMCWgamma/BaurWgamGenerator.tar.gz .
tar -xvzf BaurWgamGenerator.tar.gz
cd BaurWgamGenerator
make
#modify the RUN_DIR at the beginning of the run.sh file, to specify where to put output files
...
#Then do something like:
./run.sh cards/wPmunu.txt
#This will submit an 8nm batch job, and hopefully leave you with a baurWp.ascii file among other things

Next you have to read the baurWp.txt file you have produced above into the Pythia6 for the showering and hadronization part.

cd <yourWorkingArea>
scramv1 p CMSSW CMSSW_1_6_12
cd CMSSW_1_6_12/src
cp -p /afs/cern.ch/user/d/devdatta/public/baurMCWgamma/BaurWgamForCMSSW1612.tar.gz .
tar -zxvf BaurWgamForCMSSW1612.tar.gz 
cd GeneratorInterface/BaurWgamInterface
scramv1 b
#You'll then need some ascii output from adapted Baur Wgam Generator program in the previous link.
cmsRun FullSim.cfg

That's about all there is to it!

-- DevdattaMajumder - 12 Jun 2008