SUBROUTINE QCDGEN - Generate one event

This subroutine is used to generate one event. This proceeds as follows:

• The event is initialized by calling the HERWIG [1] subroutine HWUINE.
• The partonic hard subprocess is generated by calling the HERWIG subroutine HWEPRO.
• If the contrôl flag for hadronization, QICONT(21), is set to .TRUE. (default) the event is fully hadronized. Depending on the contrôl flag for the hadronization model, QICONT(18)=.TRUE./.FALSE., the hadronization is either performed by the corresponding HERWIG [1] or (modified) JETSET [2] routines¹, respectively (see Tables 1 and 2).
• For QICONT(21) set to .FALSE. (parton level only), the event is finalized immediately after calling HWEPRO.
• Furthermore, in this routine energy-momentum conservation in the generated event is checked.

Table 1: HERWIG [1] routines used in QCDGEN if the contrôl flag for hadronization, QICONT(21), is set to .TRUE. (default) and the contrôl flag for the hadronization model, QICONT(18), is set to .TRUE. (default).

Name	Description
HWUINE	Initialize event
HWEPRO	Generate hard subprocess
HWBGEN	Generate parton cascades
HWDHQK	Do heavy quark decays
HWCFOR	Do cluster hadronization
HWCDEC	Do cluster decay
HWDHAD	Do unstable particle decays
HWDHVY	Do heavy flavour decays
HWMEVT	Add soft underlying event if needed
HWUFNE	Finalize event

Table 2: HERWIG [1] and (modified) JETSET [2] routines used in QCDGEN if the contrôl flag for hadronization, QICONT(21), is set to .TRUE. and the contrôl flag for the hadronization model, QICONT(18), is set to .FALSE..

Name	Description
HWUINE	Initialize event
HWEPRO	Generate hard subprocess
HWBGEN	Generate parton cascades
HWUFNE	Finalize event
HERLUND	Convert HERWIG event record in HEPEVT common block
	to the respective JETSET common block
LUGIVE	Assign the hard subprocess (HARD) and instanton (INST)
	character strings in JETSET common block
LUEXEC	Simulate the whole fragmentation and decay chain
LULIST(1)	List the (first) event record
LUHEPC(1)	Convert JETSET event record contents back to
	the HEPEVT common block