Method

• Upon entry to GDECAY a binary search is made in a list of parent particles. This list is stored in the JPART structure and currently contains the particles defined in GPART [CONS300]. If the current particle cannot be found in the list, control is returned without any decay generation. Up to six decay modes and their corresponding branching ratios are then extracted from the JPART data banks (see [CONS310]).
• A decay channel is selected according to the branching ratios. If the sum of the branching ratios for a particle is not equal 100%, it is possible that no decay is selected.
• Depending on whether the two- or three-body decay is selected, either GDECA2 or GDECA3 is called to generate the four-momenta of the decay products with isotropic angular distribution in the center-of-mass system.
• The momentum vectors of the decay products are transformed into the laboratory system and rotated back into the GEANT coordinate frame. The kinematics of the products is stored in the common /GCKING/.
• When a particle decays and no branching ratio is defined, then GDECAY calls the user routine GUDCAY.

PHYS410