RELEASE NOTES 
=============

Please see History.txt for a detailed list of changes to this package.

The major points comparing this version with the 2009 release are the following:

1. This version requires HepMC (version 2.04 and above) for storing event structures
   of particle decays, and can also use Pythia 8 (version 8.180 and above is required) 
   and the C++ interfaced packages Photos (version 3.5.2 and above) and Tauola 
   (version 1.0.7 and above). These external generators are included via engine
   classes in the new sub-directory EvtGenExternal.

   Two libraries can be created for EvtGen:
   i) libEvtGen.so contains the EvtGenBase and EvtGenModel core code/decay models,
   ii) libEvtGenExternal.so contains _only_ the code within EvtGenExternal.
   This means that the external generator interface can be ignored by not 
   loading/creating the 2nd library libEvtGenExternal.so.

   In the installation instructions below, it is possible to select which external
   generators you want to use. Note, however, that the generic "DECAY.DEC" file 
   contains Pythia decays, and if Pythia is not included in the build, these 
   decays are not generated (in fact, they would need a new decay model specified). 
   Likewise, if Photos is not included, there will be no radiative corrections 
   done for particle decays.

   To use the external generators, use the following code:
   #include "EvtGenExternal/EvtExternalGenList.hh"
   #include "EvtGenBase/EvtAbsRadCorr.hh"
   #include "EvtGenBase/EvtDecayBase.hh"

   // Set up the default external generator list: Photos, Pythia and/or Tauola
   EvtExternalGenList genList;
   EvtAbsRadCorr* radCorrEngine = genList.getPhotosModel();
   std::list<EvtDecayBase*> extraModels = genList.getListOfModels();

   // Create the EvtGen generator object
   EvtGen myGenerator("decayFile.dec", "evt.pdl", randomEnginePointer,
  		      radCorrEngine, &extraModels);

   //If you don't want to use external generators, use the following:
   //EvtGen myGenerator("decayFile.dec", "evt.pdl", randomEnginePointer);

  
   The files Pythia8_README.txt and Tauola_README.txt have more details about
   using the new Pythia 8 and Tauola generators (called via the PYTHIA and TAUOLA 
   "decay.dec" model names). The new Photos generator is still called via the PHOTOS 
   "decay.dec" model name.

   It is now possible to use alias particle decays for the Pythia 8 model.
   Two Pythia 8 instances are used in EvtPythiaEngine for normal and aliased decays.
   Since the underlying code for Photos and Tauola is still Fortran, it is only
   possible to have one (unique) instance of each of these external generators. 
   This can only be fixed if these packages are converted to pure C++ code.


2. This version of EvtGen is effectively a merger of the latest LHCb and BaBar 
   EvtGenBase and EvtGenModels code. Various decay models have been added, and 
   there have been a range of bug fixes.


3. There is also a new Dalitz decay class model "GENERIC_DALITZ" 
   (EvtGenModels/EvtGenericDalitz.cpp), that should be used instead of EvtDDalitz. 
   The generic Dalitz model uses xml files to configure the resonance amplitude 
   parameters (instead of being hardcoded in EvtDDalitz):

   Decay D+
   1.0  K-  pi+  pi+  GENERIC_DALITZ MyDalitzParameters.xml;
   Enddecay

   Examples of xml Dalitz parameter files are given in the sub-directory 
   validation/DalitzFiles, e.g. see DalitzDecays.xml.


4. It is possible to use decay files in xml format. Use the python script
   convertDecayFile.py for converting decay files to the new format. 
   The src/EvtGen.cpp constructor has an additional boolean argument useXml that 
   needs to be set to true if xml decay files are to be used (default is useXml=false).
   For example, DECAY_2010.XML is the xml version of DECAY_2010.DEC.


5. Bug fixes for Bs mixing decay/CP violation amplitudes.
   Added the capability to use either coherent or incoherent mixing in EvtCPUtil. 
   One or the other can be chosen as the mixing method for the B system by
   choosing 0 (coherent) or 1 (incoherent) for the last integer argument 
   in the EvtGen() constructor.


BUILDING THE CODE
=================

To build the EvtGen code, first make sure that there is a valid (C++) version
of HepMC avilable:

HepMC    http://lcgapp.cern.ch/project/simu/HepMC/

Optionally, it is possible to use other external generators, such as Pythia8
(for Pythia decays in the DECAY.DEC file, for example), Photos (for
radiative corrections) and Tauola (for tau decays):

Pythia8  http://home.thep.lu.se/~torbjorn/Pythia.html

Photos   http://photospp.web.cern.ch/photospp/

Tauola   http://tauolapp.web.cern.ch/tauolapp/

All of these packages have instructions for building them, usually by
running their "configure" script. HepMC is used to store particle information.

Once these packages are available, set up the EvtGen release by running

./configure

within the EvtGen base directory, using the following options:

  --hepmcdir  = location of HepMC build directory (mandatory)
  --photosdir = location of Photos base directory (optional)
  --pythiadir = location of Pythia base directory (optional)
  --tauoladir = location of Tauola base directory (optional)

When successful, this will create a "config.mk" file that specifies the locations 
of the include and library directories of these additional external generators.

Then compile the EvtGen code using

make

This should create the libraries lib/libEvtGen.so and lib/libEvtGenExternal.so,
as well as the archives lib/archive/libEvtGen.a and lib/archive/libEvtGenExternal.a.
The "EvtGenExternal" library will not be created if no external generators
are specified in the configuration script.


Note that gfortran is needed to compile the code (mainly for Photos/Tauola).
The alternative (not recommended) compilers g77 (f77) can be used instead 
by changing the FC variable in the configure script.


To create an EvtGen executable, the following libraries need to be included
in the link path, owing to the dependence on the above external packages and 
Fortran code (for some EvtGenModels and for Photos/Tauola):

BASEDIR   = <EvtGen directory>
HEPMCDIR  = <base directory of HepMC>
PHOTOSDIR = <base directory of C++ Photos>
TAUOLADIR = <base directory of C++ Tauola>
PYTHIADIR = <base directory of Pythia8>

LIBS = -L${BASEDIR}/lib -L${HEPMCDIR}/lib -L${PHOTOSDIR}/lib \
       -L${TAUOLADIR}/lib -L${PYTHIADIR}/lib -lgfortran \
       -lHepMC -lPhotosCxxInterface -lPhotosFortran -lTauolaCxxInterface -lTauolaFortran \
       -lpythia8 -llhapdfdummy -lEvtGen -lEvtGenExternal

Three example programs using EvtGen can be seen in the test sub-directory along 
with the required Makefile. If there are errors about missing shared libraries,
and they have been built correctly, then the LD_LIBRARY_PATH needs to be set-up
to include them:

setenv LD_LIBRARY_PATH ${LD_LIBRARY_PATH}:<location of HepMC library directory>
setenv LD_LIBRARY_PATH ${LD_LIBRARY_PATH}:<location of Pythia 8 library directory>
setenv LD_LIBRARY_PATH ${LD_LIBRARY_PATH}:<location of Tauola library directory>
setenv LD_LIBRARY_PATH ${LD_LIBRARY_PATH}:<location of Photos library directory>
setenv LD_LIBRARY_PATH ${LD_LIBRARY_PATH}:<location of EvtGen library directory>

To use Pythia 8, the environment variable PYTHIA8DATA needs to be set to the location
of the corresponding xml documentation directory, which also contains the default values 
for particle decays and models.

setenv PYTHIA8DATA <location of Pythia 8 base directory>/xmldoc


Code validation
===============

The validation sub-directory contains code validation test cases for Pythia, Tauola 
and B mixing models. Run the "configure" script here, which should create a file 
called extraConfig.mk, and build the examples using "make". Note that some extra 
configuration may be necessary to set the location of the ROOT libraries, which are 
only used to create ntuples and plots for the validation examples.

The script genAllDecayExamples.sh runs other scripts that generate a range of decay 
modes using the genExampleRootFiles.cc program. The script compareAllDecays.sh runs 
a range of scripts that creates comparison plots using the compareRootFiles.cc program. 
For now, the comparisons use the same plots, but each of the "compare.sh" files can 
be edited to compare any two versions of ROOT data created by the 
genExampleRootFiles.cc program.

The testCPVDecays.cc program runs a test for the B mixing decay model.

Examples
========

Some examples are provided in the test sub-directory. 

To run these, first build EvtGen, then run "configure", then type "make" in the 
test directory. Note that these tests require ROOT to be installed. 
Running the script "./do_tests" will run a series of EvtGen examples. 
Example decay files are in the test/exampleFiles sub-directory.