PythiaAndPowhegStudies

Repository with scripts to perform studies with Pythia8 and Powheg

Instructions for Pythia8 installation as ROOT plugin

• Download and installation of Pythia8

  Download and untar a specific Pythia8 release from http://home.thep.lu.se/~torbjorn/Pythia.html. For example for version 8.243:

  wget http://home.thep.lu.se/~torbjorn/pythia8/pythia8243.tgz
  tar xvfz pythia8243.tgz
  cd pythia8243

  Configuration for 64bit systems:

  ./configure --enable-64bit --enable-shared

  All configuration options can be listed with

  ./configure --help

  They include also a variety of external packages that can be enabled via

  --with-PACKAGE[=DIR]

  They include root for the usage of ROOT trees and histograms with pythia, evtgen for the particle decays with the EvtGen package, powheg for the hard process production with POWHEGBOX matrix element executables, python for an interface to use pythia in python. These options are however not necessary for the installation of Pythia8 as ROOT plugin.

  Compile Pythia8:

  make -J N

  On MacOs, copy the dynamic shared library:

  cd lib
  cp libpythia8.dylib libpythia8.so

  Setup the environment including in the .bashrc (.bash_profile)

  export PYTHIA8=$HOME/pythia8243
  export PYTHIA8DATA=$HOME/pythia8243/share/Pythia8/xmldoc
  DYLD_LIBRARY_PATH=$PYTHIA8/lib:$DYLD_LIBRARY_PATH

• Compilation of ROOT

  ROOT has to be recompiled with the following configurations:

  ./configure --all --with-gsl-incdir="/usr/local/include/gsl" --with-gsl-libdir="/usr/local/lib" --enable-pythia8 --with-pythia8-incdir=$PYTHIA8/include --with-pythia8-libdir=$PYTHIA8/lib

  If ROOT in the AliPhysics installation is used, the root.sh recipy in alidist has to be modified, adding in the configurations:

  -Dpythia8=ON                                                                     \
  -DPYTHIA8_DIR=$PYTHIA8                                                           \
  -DPYTHIA8_INCLUDE_DIR=$PYTHIA8/include                                           \
  -DPYTHIA8_LIBRARY=$PYTHIA8/lib/libpythia8.so                                     \

  ROOT has then to be recompiled

• Test that installation was successful

  Open root session and execute Pythia8 tutorial:

  root -l
  .x $ROOTSYS/tutorials/pythia/pithia8.C

Instructions for POWHEG-BOX installation

• Download and install LHAPDF

  For the installation follow the instructions in https://lhapdf.hepforge.org/install.html

  Setup the environment including in the .bashrc (.bash_profile)

  export LHAPDF=/path/for/installation
  export PATH=$PATH:$LHAPDF/bin
  LD_LIBRARY_PATH=$LHAPDF/lib:$LD_LIBRARY_PATH
  export LHAPDF_DATA_PATH=$LHAPDF/share/LHAPDF

  Copy sets of pdfs in $LHAPDF_DATA_PATH from CERN CVMFS /cvmfs/sft.cern.ch/lcg/external/lhapdfsets/current/

• Download and install POWHEG-BOX

  Download the package with

  svn checkout --username anonymous --password anonymoussvn://powhegbox.mib.infn.it/trunk/POWHEG-BOX  

  Install the desired process (heavy quarks hvq in this case)

  cd POHEG-BOX/hvq
  make pwhg_main
  make main-PYTHIA-lhef