The primary vertex nominal position and sigmas for fluctuation are defined by the FFREAD card BEAM which is defined on page 1.5.5. The routine VTXGEN is used for the vertex fluctuation.
Fixed vertex position can be obtained by setting the BEAM card parameters 4,5 and 6 to 0. 0. 0. which implies no vertex fluctuation.
The standard GUKINE flow chart looks as follows:
* | | |->GUKINE (*) generates or reads event input kinematics * | | | | * | | | |->CKNTUP (*) kinematics read from Ntuples * | | | | | * | | | | |->CKREAD (*) Read from ntuples * | | | | | | * | | | | | |->IO_UNIT (*) * | | | | | | * | | | | | |->HGNTF * | | | | | | * | | | | | |->KIU_LUHEPC (*) * | | | | | | * | | | | | |->LULIST * | | | | | * | | | | |->CKHEPG (*) Create GEANT Kine structure * | | | | |->VTXGEN (*) * | | | | | * | | | | |->GSVERT * | | | | | * | | | | |->CKPYTIDG (*) * | | | | | * | | | | |->GSKINE (*) * | | | | * | | | |->CKSIMPL (*) single particle event with fixed theta, * | | | | | phi, p_T * | | | | |->VTXGEN (*) * | | | | | * | | | | |->TRAMUL (*) * | | | | | * | | | | |->GSVERT * | | | | | * | | | | |->GIVEPT (*) * | | | | | * | | | | |->PARTYP (*) * | | | | | * | | | | |->GSKINE * | | | | * | | | |->USKINE (*) user kinematics * | | | | * | | | |->GPVERT * | | | | * | | | |->GPKINE
For cuts defined on KINE card one uses the integer function ICKREJ which takes the particle momentum as an input argument and returns 1, if the particle is outside the cuts.