How to simulate D mesons in GSTAR 

By Pavel Nevski
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D meason has many decays (4 pages in PDG handbook for D+, 5 pages for D0) and GEANT may have not more than 6 decay channels. Also, the number of products in each decay in geant is limited by 3.

If you want to have a general (more or less complete) simulation of a D-meson decay have to generate and decay D meson in an external program (i.e. PYTHIA). Then you have to write the decay product (including D-meason itself with it's PDG code) in a txt file as shown at GSTAR web or in an n-tuple using interface in $STAR/pams/gen/heptup.f

If you are interested in few selected decay channels, you can add D meson and selected channels to $STAR/pams/sim/gstar/gstar_part.g There is already an example put there as a comment:

* For D+, include only K0_S + pi+ decay mode pmj 16/2/95
* Particle D_plus code=35 TrkTyp=4 mass=1.869 charge=1 tlife=1.057e-12,
* pdg=411 bratio= { 1, } mode= { 1608, }

* For D0, include only K+ + pi- decay mode pmj 16/2/95
* Particle D0 code=37 TrkTyp=3 mass=1.865 charge=0 tlife=0.415e-12,
* pdg=421 bratio= { 1, } mode= { 1208, }

It is up to you to uncomment it and to tune the parameters as you like