* * $Id: hwigin.F,v 1.1.1.1 1996/03/08 17:02:16 mclareni Exp $ * * $Log: hwigin.F,v $ * Revision 1.1.1.1 1996/03/08 17:02:16 mclareni * Herwig58 * * *CMZ : 29/08/94 11.51.48 by Unknown *-- Author : CDECK ID>, HWIGIN. *CMZ :- -14/07/92 19.49.55 by Mike Seymour *-- Author : Bryan Webber C---------------------------------------------------------------------- SUBROUTINE HWIGIN C SETS INPUT PARAMETERS C---------------------------------------------------------------------- #include "herwig58/herwig58.inc" DOUBLE PRECISION FAC INTEGER I,J CHARACTER*28 TITLE DATA TITLE/'HERWIG 5.8 AUGUST 1994'/ WRITE (6,8) TITLE 8 FORMAT(//10X,A28/) C---PRINT OPTIONS: C C IPRINT=0 NO PRINTOUT C 1 PRINT SELECTED INPUT PARAMETERS C 2 1 + TABLE OF PARTICLE CODES AND PROPERTIES C 3 2 + TABLES OF SUDAKOV FORM FACTORS C---------------------------------------------------------------------- C PRNDEC=.TRUE. to use decimal for track numbers in event listing C .FALSE. to use hexadecimal C---------------------------------------------------------------------- IPRINT=1 PRNDEC=(NMXHEP.LE.9999) C---UNIT FOR READING SUDAKOV FORM FACTORS C (IF ZERO THEN COMPUTE THEM) LRSUD=0 C---UNIT FOR WRITING SUDAKOV FORM FACTORS C (IF ZERO THEN NOT WRITTEN) LWSUD=77 C---UNIT FOR WRITING EVENT DATA IN HWANAL C (IF ZERO THEN NOT WRITTEN) LWEVT=0 C---SEEDS FOR RANDOM NUMBER GENERATOR (CALLED HWRGEN) NRN(1)= 17673 NRN(2)= 63565 C---AZIMUTHAL CORRELATIONS? C THESE INCLUDE SOFT GLUON (INSIDE CONE) AZSOFT=.TRUE. C AND NEAREST-NEIGHBOUR SPIN CORRELATIONS AZSPIN=.TRUE. C---MATCH HARD EMISSION IN E+E- AND DIS TO MATRIX-ELEMENT HARDME=.TRUE. C---MATCH SOFT EMISSION IN E+E- AND DIS TO MATRIX-ELEMENT SOFTME=.TRUE. C Electromagnetic fine structure constant: Thomson limit ALPHEM=.0072993 C---QCD LAMBDA: CORRESPONDS TO 5-FLAVOUR C LAMBDA-MS-BAR AT LARGE X ONLY QCDLAM=0.18 C---NUMBER OF COLOURS NCOLO=3 C---NUMBER OF FLAVOURS NFLAV=6 C---QUARK, GLUON AND PHOTON VIRTUAL MASS CUTOFFS IN C PARTON SHOWER (ADDED TO MASSES GIVEN BELOW) VQCUT=0.48 VGCUT=0.10 VPCUT=0.40 ALPFAC=1 C---D,U,S,C,B,T QUARK MASSES (IN THAT ORDER) RMASS(1)=0.32 RMASS(2)=0.32 RMASS(3)=0.5 RMASS(4)=1.8 RMASS(5)=5.2 RMASS(6)=170. C---GLUON MASS RMASS(13)=0.75 C C---W+/- AND Z0 MASSES RMASS(198)=80.4 RMASS(199)=80.4 RMASS(200)=91.2 C---HIGGS BOSON MASS RMASS(201)=150. C---WIDTHS OF W, Z, HIGGS GAMW=2.0 GAMZ=2.5 GAMH=0.02 C Include additional neutral, massive vector boson (Z') ZPRIME=.FALSE. C Z' mass and width RMASS(202)=500. GAMZP=5. C Lepton (EPOLN) and anti-lepton (PPOLN) beam polarisations used in: C e+e- --> ffbar/qqbar g; and l/lbar N DIS. C Cpts. 1,2 Transverse polarisation; cpt. 3 longitudinal polarisation. C Note require POLN(1)**2+POLN(2)**2+POLN(3)**2 < 1. DO 20 I=1,3 EPOLN(I)=0. 20 PPOLN(I)=0. C------------------------------------------------------------------------ C Specify couplings of weak vector bosons to fermions: C C electric current: QFCH(I)*e*G_mu (electric charge, e>0) C weak neutral current: [VFCH(I,J).1+AFCH(I,J).G_5]*e*G_mu C weak charged current: SQRT(VCKM(K,L)/2.)*g*(1+G_5)*G_mu C C I= 1- 6: d,u,s,c,b,t (quarks) C =11-16: e,nu_e,mu,nu_mu,tau,nu_tau (leptons) (`I=IDHW-110') C J=1 for minimal SM: C =2 for Z' couplings (ZPRIME=.TRUE.) C K=1,2,3 for u,c,t; L=1,2,3 for d,s,b C------------------------------------------------------------------------ C Minimal standard model neutral vector boson couplings C VFCH(I,1)=(T3/2-Q*S^2_W)/(C_W*S_W); AFCH(I,1)=T3/(2*C_W*S_W) C sin**2 Weinberg angle SWEIN=.23 FAC=1./SQRT(SWEIN*(1.-SWEIN)) DO 30 I=1,3 C Down-type quarks J=2*I-1 QFCH(J)=-1./3. VFCH(J,1)=(-0.25+SWEIN/3.)*FAC AFCH(J,1)= -0.25*FAC C Up-type quarks J=2*I QFCH(J)=+2./3. VFCH(J,1)=(+0.25-2.*SWEIN/3.)*FAC AFCH(J,1)= +0.25*FAC C Charged leptons J=2*I+9 QFCH(J)=-1. VFCH(J,1)=(-0.25+SWEIN)*FAC AFCH(J,1)= -0.25*FAC C Neutrinos J=2*I+10 QFCH(J)=0. VFCH(J,1)=+0.25*FAC AFCH(J,1)=+0.25*FAC 30 CONTINUE C Additional Z' couplings (To be set by the user) IF (.NOT.ZPRIME) THEN DO 40 I=1,6 AFCH(I,2)=0. AFCH(10+I,2)=0. VFCH(I,2)=0. VFCH(10+I,2)=0. 40 CONTINUE ENDIF C Cabibbo-Kobayashi-Maskawa matrix elements squared (PDG '92): C sin**2 of Cabibbo angle SCABI=.0488 C u ---> d,s,b VCKM(1,1)=1.-SCABI VCKM(1,2)=SCABI VCKM(1,3)=0.0 C c ---> d,s,b VCKM(2,1)=SCABI VCKM(2,2)=1.-SCABI VCKM(2,3)=0.002 C t ---> d,b,s VCKM(3,1)=0.0 VCKM(3,2)=0.002 VCKM(3,3)=0.998 C---GAUGE BOSON DECAYS DO 10 I=1,12 BRHIG(I)=1.D0/12 ENHANC(I)=1.D0 10 IF (I.LE.MODMAX) MODBOS(I)=0 C C THE iTH GAUGE BOSON DECAY PER EVENT IS CONTROLLED BY MODBOS AS FOLLOWS C MODBOS(i) W DECAY Z DECAY C 0 all all C 1 qqbar qqbar C 2 enu e+e- C 3 munu mu+mu- C 4 taunu tau+tau- C 5 enu & munu ee & mumu C 6 all nunu C 7 all bbbar C >7 all all C BOSON PAIRS (eg FROM HIGGS DECAY) ARE CHOSEN FROM MODBOS(i),MODBOS(i+1 C C---CONTROL OF LARGE EMH BEHAVIOUR (SEE HWHIGM FOR DETAILS) IOPHIG=1 GAMMAX=10. C Specicify approximation used in HWHIGA IAPHIG=1 C---MASSES OF HYPOTHETICAL NEW QUARKS GO C INTO 209-214 (ANTIQUARKS IN 215-220) C ID = 209,210 ARE B',T' WITH DECAYS T'->B'->C C 211,212 ARE B',T' WITH DECAYS T'->B'->T C 215-218 ARE THEIR ANTIQUARKS RMASS(209)=150. RMASS(215)=150. C---MAXIMUM CLUSTER MASS PARAMETERS C N.B. LIMIT FOR Q1-Q2BAR CLUSTER MASS C IS (CLMAX**CLPOW + (QM1+QM2)**CLPOW)**(1/CLPOW) CLMAX=3.35 CLPOW=2.0 C---MASS SPECTRUM OF PRODUCTS IN CLUSTER C SPLITTING ABOVE CLMAX - FLAT IN M**PSPLT PSPLT=1.0 C---KINEMATIC TREATMENT OF CLUSTER DECAY C 0=ISOTROPIC, 1=REMEMBER DIRECTION OF PERTURBATIVELY PRODUCED QUARKS CLDIR=1 C IF CLDIR=1, DO GAUSSIAN SMEARING OF DIRECTION: C ACTUALLY EXPONENTIAL IN 1-COS(THETA) WITH MEAN CLSMR CLSMR=0.0 C---TREATMENT OF LOWER LIMIT FOR SPACELIKE EVOLUTION C 0=EVOLUTION STOPS AT QSPAC, BUT STRUCT FUNS CAN GET CALLED AT C SMALLER SCALES IN FORCED EMISSION (EQUIVALENT TO V5.7 AND EARLIER) C 1=EVOLUTION STOPS AT QSPAC, STRUCTURE FUNCTIONS FREEZE AT QSPAC C 2=EVOLUTION CONTINUES TO INFRARED CUT, BUT S.F.S FREEZE AT QSPAC ISPAC=0 C---LOWER LIMIT FOR SPACELIKE EVOLUTION QSPAC=2.5 C---SWITCH OFF SPACE-LIKE SHOWERS NOSPAC=.FALSE. C---INTRINSIC PT OF SPACELIKE PARTONS (RMS) PTRMS=0.0 C---MASS PARAMETER IN REMNANT FRAGMENTATION BTCLM=1.0 C---STRUCTURE FUNCTION SET: C SET MODPDF(I)=MODE AND AUTPDF='AUTHOR GROUP' TO USE CERN LIBRARY C PDFLIB PACKAGE FOR STRUCTURE FUNCTIONS IN BEAM I MODPDF(1)=-1 MODPDF(2)=-1 AUTPDF(1)='MRS' AUTPDF(2)='MRS' C OR SET MODPDF(I)=-1 TO USE BUILT-IN STRUCTURE FUNCTION SET: C 1,2 FOR DUKE+OWENS SETS 1,2 (SOFT/HARD GLUE) C 3,4 FOR EICHTEN+AL SETS 1,2 (NUCLEONS ONLY) C 5 FOR OWENS SET 1.1 (SOFT GLUE ONLY) NSTRU=5 C PARAMETER FOR B CLUSTER DECAY TO 1 HADRON. IF MCL IS CLUSTER MASS C AND MTH IS THRESHOLD FOR 2-HADRON DECAY, THEN PROBABILITY IS C 1 IF MCL(1+B1LIM)*MTH, WITH LINEAR INTERPOLATION, B1LIM=0.0 C---B DECAY PACKAGE ('HERW'=>HERWIG, 'EURO'=>EURODEC, 'CLEO'=>CLEO) BDECAY='HERW' C---HARD SUBPROCESS SCALE TO BE USED IN BOSON-GLUON FUSION C IF (BGSHAT) THEN SCALE=SHAT C ELSE SCALE=2.*SHAT*THAT*UHAT/(SHAT**2+THAT**2+UHAT**2) BGSHAT=.FALSE. C---RECONSTRUCT DIS EVENTS IN BREIT FRAME BREIT=.TRUE. C---TREAT ALL EVENTS IN THEIR CMF (ELSE USE LAB FRAME) USECMF=.TRUE. C---PROBABILITY OF UNDERLYING SOFT EVENT: PRSOF=1. C---MULTIPLICITY ENHANCEMENT FOR UNDERLYING SOFT EVENT: C NCH = NCH(PPBAR AT ENSOF*SQRT(S)) ENSOF=1. C---MIN AND MAX JET RAPIDITIES IN QCD 2->2, C HEAVY FLAVOUR AND DIRECT PHOTON PROCESSES YJMAX=8. YJMIN=-YJMAX C---MIN AND MAX PARTON TRANSVERSE MOMENTUM C IN ELEMENTARY 2 -> 2 SUBPROCESSES PTMIN=1D1 PTMAX=1D8 C---UPPER LIMIT ON HARD PROCESS SCALE QLIM=1D8 C---MAX PARTON THRUST IN 2->3 HARD PROCESSES THMAX=0.9 C---MIN AND MAX DILEPTON INVARIANT MASS IN DRELL-YAN PROCESS EMMIN=0D0 EMMAX=1D8 C---MIN AND MAX ABS(Q**2) IN DEEP INELASTIC LEPTON SCATTERING Q2MIN=0D0 Q2MAX=1D10 C---MIN AND MAX ABS(Q**2) IN WEISZACKER-WILLIAMS APPROXIMATION Q2WWMN=0. Q2WWMX=4. C---IF PHOMAS IS NON-ZERO, PARTON DISTRIBUTION FUNCTIONS FOR OFF-SHELL C PHOTONS IS DAMPED, WITH MASS PARAMETER = PHOMAS PHOMAS=0. C---MIN AND MAX FLAVOURS GENERATED BY IPROC=9100,9110,9130 IFLMIN=1 IFLMAX=5 C---MAX Z IN J/PSI PHOTO- AND ELECTRO- PRODUCTION ZJMAX=0.9 C---MIN AND MAX BJORKEN-Y YBMIN=0. YBMAX=1. C---MAX COS(THETA) FOR W'S IN E+E- -> W+W- CTMAX=0.9999 C---A PRIORI WEIGHTS FOR VECTOR AND C TENSOR MESONS AND DECUPLET BARYONS VECWT=1. TENWT=1. DECWT=1. C---A PRIORI WEIGHTS FOR D,U,S,C,B,T QUARKS C AND DIQUARKS (IN THAT ORDER) PWT(1)=1. PWT(2)=1. PWT(3)=1. PWT(4)=1. PWT(5)=1. PWT(6)=1. PWT(7)=1. C---ETA-ETAPRIME MIXING ANGLE IN DEGREES ETAMIX=-20 C---PARAMETERS FOR NON-PERTURBATIVE C SPLITTING OF GLUONS INTO C DIQUARK-ANTIDIQUARK PAIRS: C SCALE AT WHICH GLUONS CAN C BE SPLIT INTO DIQUARKS C (0.0 FOR NO SPLITTING) QDIQK=0.0 C PROBABILITY (PER UNIT LOG C SCALE) OF DIQUARK SPLITTING PDIQK=5.0 C---PARAMETERS FOR IMPORTANCE SAMPLING C ASSUME QCD 2->2 DSIG/DET FALLS LIKE ET**(-PTPOW) C WHERE ET=SQRT(MQ**2+PT**2) FOR HEAVY FLAVOURS PTPOW=4. C ASSUME DRELL-YAN DSIG/DEM FALLS LIKE EM**(-EMPOW) EMPOW=4. C ASSUME DEEP INELASTIC DSIG/DQ**2 FALLS LIKE (Q**2)**(-Q2POW) Q2POW=2.5 C---GENERATE UNWEIGHTED EVENTS (EVWGT=AVWGT)? NOWGT=.TRUE. C---DEFAULT MEAN EVENT WEIGHT AVWGT=1. C---ASSUMED MAXIMUM WEIGHT (ZERO TO RECOMPUTE) WGTMAX=0. C---MAX NO OF (CODE.GE.100) ERRORS MAXER=10 C---MAX NO OF EVENTS TO PRINT MAXPR=1 C---TIME (SEC) NEEDED TO TERMINATE GRACEFULLY TLOUT=5. C---CURRENT NO OF EVENTS NEVHEP=0 C---CURRENT NO OF ENTRIES IN /HEPEVT/ NHEP=0 C---ISTAT IS STATUS OF EVENT (I.E. STAGE IN PROCESSING) ISTAT=0 C---IERROR IS ERROR CODE IERROR=0 C---MORE TECHNICAL PARAMETERS - SHOULDN'T NEED ADJUSTMENT C---PI PIFAC=ACOS(-1.D0) C Cross-section conversion factor (hbar.c)**2 GEV2NB=389385 C---NUMBER OF SHOTS FOR INITIAL MAX WEIGHT SEARCH IBSH=2000 C---RANDOM NO. SEEDS FOR INITIAL MAX WEIGHT SEARCH IBRN(1)=1246579 IBRN(2)=8447766 C---NUMBER OF ENTRIES IN LOOKUP TABLES OF SUDAKOV FORM FACTORS NQEV=1024 C---MAXIMUM BIN SIZE IN Z FOR SPACELIKE BRANCHING ZBINM=0.05 C---MAXIMUM NUMBER OF Z BINS FOR SPACELIKE BRANCHING NZBIN=100 C---MAXIMUM NUMBER OF BRANCH REJECTIONS (TO AVOID INFINITE LOOPS) NBTRY=200 C---MAXIMUM NUMBER OF TRIES TO GENERATE CLUSTER DECAY NCTRY=200 C---MAXIMUM NUMBER OF TRIES TO GENERATE MASS REQUESTED NETRY=50 C---MAXIMUM NUMBER OF TRIES TO GENERATE SOFT SUBPROCESS NSTRY=200 C---PRECISION FOR GAUSSIAN INTEGRATION ACCUR=1.E-6 C---ORDER OF INTERPOLATION IN SUDAKOV TABLES INTER=3 C---ORDER TO USE FOR ALPHAS IN SUDAKOV TABLES SUDORD=1 999 END