New version 1.5.0
EvtGen version 1.5.0 (R01-05-00) is now available. Recommended external packages are HepMC 2.06.09, pythia 8.186, Photos++ 3.61 and Tauola++ 1.1.5. The main changes with respect to version 1.4.0 are:
- Physics model updates and additions:
1. Bc → scalar ell nu (EvtBcSMuNu) and Bc → tensor ell nu (EvtBcTMuNu) decays
2. EvtbsToLLLLAmp and EvtbsToLLLLHyperCP for B0_q → l+ l- l+ l- decays
3. Modified EvtSVPHelAmp and added a new EvtSVPHelCPMix model, implementing the complete mixing phenomenology of Bs to vector gamma decays
4. Added the EvtB2MuMuMuNu model for simulating the very rare four-leptonic decays B- → mu+ mu- anti-nu_mu mu-
5. Fixed form-factor calculations for the BTOSLLBALL model 6 used to generate b → sll decays. Affects B → K*ll, B->rholl and B → omega ll, particularly the electron modes
6. EvtD0mixDalitz code cleanup, inverted q/p for decays of D0bar (simplifies user decay files) and fixed y parameter bug.
- Changed the installation and set-up script name to be just setupEvtGen.sh; it uses the VERSION variable to specify the required tag. List of tags are available using either “svn ls -v http://svn.cern.ch/guest/evtgen/tags”
or by going to tags.
Modified the configure and setupEvtGen.sh scripts to work on Mac; needed Mac compilation patch files added to the new “platform” subdirectory.
- Updated EvtGenExternal/EvtPhotosEngine to check that additional particles from the outgoing vertex are indeed (FSR) photons, since later versions of PHOTOS introduce pair emission, where particles may not always be photons.
Updated the configure script to automatically select the library names for PHOTOS++; version 3.56 and below
uses Fortran, version 3.61 and above uses C++ only (default). Avoid using v3.60, since it does not work. This needs the PHOTOS libraries built before EvtGen is configured.
Changed the initialisation order of the infrared cut-off in EvtPhotosEngine. This actually has no effect, since the exponentiation function sets it to the same 1e-7 value, but it’s now in the correct order if we need to update it.
- Added Mersenne-Twister random number generator (RNG) EvtMTRandomEngine. It requires c++11 compiler features (>= gcc 4.7), which should automatically be enabled by the configure script. Introduced the preprocessor environment variable EVTGEN_CPP11 for c++11 features. EvtMTRandomEngine is the default RNG for the validation and test examples
if c++11 features are enabled.
- Fixed accessed uninitialised memory in EvtPDL.cpp, line 213.
- Reimplemented the real Spence function in C++ and removed its fortran implementation.
- Added the genRootDecayChain.cc validation program to create ROOT files containing information about the complete decay tree.
Added a phase-space test validation/genPHSP.sh and PhaseSpacePlots.C to visually check the flatness of Dalitz plots in order to ensure that the RNG is not producing biased results that depend on particle ordering.
- Changed the width of chi_b1 in evt.pdl from 9.8928 GeV to zero.