PROGRAM PYXTRA C...Long example how to interface user-defined processes to PYTHIA C...based on the Les Houches commonblock agreement. Generates events C...of several different kinds, to test the new code under varied C...conditions, but kinematics selection and cross sections are C...completely unphysical. C...Double precision and integer declarations. IMPLICIT DOUBLE PRECISION(A-H, O-Z) INTEGER PYK,PYCHGE,PYCOMP C...User process event common block. INTEGER MAXNUP PARAMETER (MAXNUP=500) INTEGER NUP,IDPRUP,IDUP,ISTUP,MOTHUP,ICOLUP DOUBLE PRECISION XWGTUP,SCALUP,AQEDUP,AQCDUP,PUP,VTIMUP,SPINUP COMMON/HEPEUP/NUP,IDPRUP,XWGTUP,SCALUP,AQEDUP,AQCDUP,IDUP(MAXNUP), &ISTUP(MAXNUP),MOTHUP(2,MAXNUP),ICOLUP(2,MAXNUP),PUP(5,MAXNUP), &VTIMUP(MAXNUP),SPINUP(MAXNUP) C...Standard PYTHIA commonblocks. COMMON/PYJETS/N,NPAD,K(4000,5),P(4000,5),V(4000,5) COMMON/PYDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200) COMMON/PYDAT3/MDCY(500,3),MDME(8000,2),BRAT(8000),KFDP(8000,5) COMMON/PYSUBS/MSEL,MSELPD,MSUB(500),KFIN(2,-40:40),CKIN(200) COMMON/PYPARS/MSTP(200),PARP(200),MSTI(200),PARI(200) C...Extra commonblock to transfer run info. COMMON/PRIV/MODE,NLIM C...Local arrays. DIMENSION IPRID(100) C...Switch process mode; agrees with IDWTUP code (+-1,+-2,+-3,+-4). MODE=2 C...Simulate limited suppy of events of Wbb kind. NLIM=100 C...Maximum number of events to generate. NEV=100 C...Set pi0 stable to trim event listings. MDCY(PYCOMP(111),1)=0 C...Expanded event listing (required for histogramming). MSTP(125)=2 C...Histograms. CALL PYBOOK(1,'charged multiplicity',100,-1D0,399D0) CALL PYBOOK(2,'starting virtualities, 2 -> 2',100,0D0,200D0) CALL PYBOOK(3,'starting virtualities, 2 -> 3',100,0D0,200D0) CALL PYBOOK(4,'starting virtualities, 2 -> 4',100,0D0,200D0) CALL PYBOOK(5,'starting virtualities, 2 -> 5',100,0D0,200D0) CALL PYBOOK(6,'starting virtualities, 2 -> 6',100,0D0,200D0) CALL PYBOOK(7,'starting virtualities, 2 -> 7',100,0D0,200D0) C...Initialize with external process. CALL PYINIT('USER',' ',' ',0D0) NACC=0 NPRID=0 C...Event loop; generate event; check it was obtained or quit. DO 130 IEV=1,NEV CALL PYEVNT IF(MSTI(51).EQ.1) GOTO 140 NACC=NACC+1 IF(MOD(IEV-1,10).EQ.0) THEN PRINT*,' IEV = ',IEV CALL PYLIST(7) CALL PYLIST(2) ENDIF CALL PYEDIT(3) CALL PYFILL(1,DBLE(N),1D0) 130 CONTINUE C...Statistics and histograms. 140 CALL PYSTAT(1) CALL PYHIST END C********************************************************************* C...UPINIT C...Routine to be called by user to set up user-defined processes. C...Code below only intended as example, without any claim of realism. C...Especially it shows what info needs to be put in HEPRUP. SUBROUTINE UPINIT C...Double precision and integer declarations. IMPLICIT DOUBLE PRECISION(A-H, O-Z) IMPLICIT INTEGER(I-N) CHARACTER*80 CHAR_READ C...User process initialization commonblock. INTEGER MAXPUP PARAMETER (MAXPUP=100) INTEGER IDBMUP,PDFGUP,PDFSUP,IDWTUP,NPRUP,LPRUP DOUBLE PRECISION EBMUP,XSECUP,XERRUP,XMAXUP COMMON/HEPRUP/IDBMUP(2),EBMUP(2),PDFGUP(2),PDFSUP(2), &IDWTUP,NPRUP,XSECUP(MAXPUP),XERRUP(MAXPUP),XMAXUP(MAXPUP), &LPRUP(MAXPUP) SAVE /HEPRUP/ C...Extra commonblock to transfer run info. COMMON/PRIV/MODE,NLIM SAVE/PRIV/ C....Pythia commonblock - needed for setting PDF's; see below. C COMMON/PYPARS/MSTP(200),PARP(200),MSTI(200),PARI(200) C SAVE /PYPARS/ C...Set incoming beams: Tevatron Run II. IDBMUP(1)=2212 IDBMUP(2)=-2212 EBMUP(1)=980D0 EBMUP(2)=980D0 C...Set PDF's of incoming beams: CTEQ 5L. C...Note that Pythia will not look at PDFGUP and PDFSUP. PDFGUP(1)=4 PDFSUP(1)=46 PDFGUP(2)=PDFGUP(1) PDFSUP(2)=PDFSUP(1) C...If you want Pythia to use PDFLIB, you have to set it by hand. C...(You also have to ensure that the dummy routines C...PDFSET, STRUCTM and STRUCTP in Pythia are not linked.) C MSTP(52)=2 C MSTP(51)=1000*PDFGUP(1)+PDFSUP(1) C...Decide on weighting strategy: unweighted on input. IDWTUP=MODE C...Number of external processes. NPRUP=1 C.....read through data file to find maximum weight....only first time WTMAX=0D0 XSTOT=0D0 DO I=1,10000000 READ(77,*,END=777) NPARTS,KNTEV,WTEVNT IF(WTEVNT.GT.WTMAX) WTMAX=WTEVNT XSTOT=XSTOT+WTEVNT DO J=1,12 READ(77,*) CHAR_READ ENDDO ENDDO 777 CONTINUE REWIND(77) XSECUP(1)=XSTOT XMAXUP(1)=WTMAX LPRUP(1)=661 RETURN END C********************************************************************* C...UPEVNT C...Sample routine to generate events of various kinds. C...Not intended to be realistic, but rather to show in closed C...and understandable form what such a routine might look like. C...Especially it shows what info needs to be put in HEPEUP. SUBROUTINE UPEVNT C...Double precision and integer declarations. IMPLICIT DOUBLE PRECISION(A-H, O-Z) IMPLICIT INTEGER(I-N) COMMON/PYPARS/MSTP(200),PARP(200),MSTI(200),PARI(200) C...Extra commonblock to transfer run info. COMMON/PRIV/MODE,NLIM SAVE/PRIV/ C...User process event common block. INTEGER MAXNUP PARAMETER (MAXNUP=500) INTEGER NUP,IDPRUP,IDUP,ISTUP,MOTHUP,ICOLUP DOUBLE PRECISION XWGTUP,SCALUP,AQEDUP,AQCDUP,PUP,VTIMUP,SPINUP COMMON/HEPEUP/NUP,IDPRUP,XWGTUP,SCALUP,AQEDUP,AQCDUP,IDUP(MAXNUP), &ISTUP(MAXNUP),MOTHUP(2,MAXNUP),ICOLUP(2,MAXNUP),PUP(5,MAXNUP), &VTIMUP(MAXNUP),SPINUP(MAXNUP) SAVE /HEPEUP/ C...If PYTHIA is supposed to select event type, do not modify this choice. IF(IABS(MODE).LE.2) THEN IDPRUP=661 C...Else free hands to mix; here evenly. ELSE ENDIF 99 CONTINUE C...Zero some arrays in common blocks to simplify filling. NUP=12 DO 100 I=1,NUP MOTHUP(1,I)=0 MOTHUP(2,I)=0 ICOLUP(1,I)=0 ICOLUP(2,I)=0 SPINUP(I)=0D0 PUP(1,I)=0D0 PUP(2,I)=0D0 PUP(5,I)=0D0 VTIMUP(I)=0D0 100 CONTINUE READ(77,*,END=888) NUP,ID,XWGTUP READ(77,*,END=888) (IDUP(I),I=1,NUP) ISTUP(1)=-1 ISTUP(2)=-1 DO I=3,NUP ISTUP(I)=1 ENDDO READ(77,*,END=888) (MOTHUP(1,I),I=1,NUP) READ(77,*,END=888) (MOTHUP(2,I),I=1,NUP) READ(77,*,END=888) (ICOLUP(1,I),I=1,NUP) READ(77,*,END=888) (ICOLUP(2,I),I=1,NUP) DO I=1,NUP READ(77,*,END=888) IDUMB,PUP(4,I),(PUP(J,I),J=1,3) TEST=PUP(1,I)**2+PUP(2,I)**2+PUP(3,I)**2-PUP(4,I)**2 IF(TEST.LE.0D0) THEN PUP(5,I)=DSQRT(-TEST) ELSEIF(DABS(TEST).LT.1D-6) THEN PUP(5,I)=0D0 ELSE PUP(5,I)=-1D0 PRINT*,' NEGATIVE MASS ' ENDIF ENDDO C...Some other compulsory quantities. SCALUP=-1D0 RETURN 888 CONTINUE REWIND(77) GOTO 99 RETURN END