| 0795afa3 |
1 | #include "isajet/pilot.h" |
| 2 | SUBROUTINE QCDZ(J) |
| 3 | C |
| 4 | C Auxiliary routine for QCDJET. Generate Z for parton J and |
| 5 | C store in ZZC(J). Add possible new partons to /JETSET/. |
| 6 | C |
| 7 | C Include GM, W+, W-, and Z0 radiation. |
| 8 | C |
| 9 | C Ver 7.20: Anomalous dimensions were coded incorrectly! |
| 10 | C |
| 11 | #if defined(CERNLIB_IMPNONE) |
| 12 | IMPLICIT NONE |
| 13 | #endif |
| 14 | #include "isajet/itapes.inc" |
| 15 | #include "isajet/jetset.inc" |
| 16 | #include "isajet/jwork.inc" |
| 17 | #include "isajet/qcdpar.inc" |
| 18 | #include "isajet/wcon.inc" |
| 19 | #include "isajet/const.inc" |
| 20 | #include "isajet/q1q2.inc" |
| 21 | C |
| 22 | REAL PQQ,PGQ,PQG,PGG,Z,PGSGS,PQSQS,ALFAS,QQ,AM0,ZC,AMASS |
| 23 | REAL GAMQQ,GAMGG,PROBG,PROBQ,RND,RANF,ZGEN,GZ |
| 24 | REAL GAMZC,GAMSUM,AM1W,AM2W,T1W,T2W,ZCW,T0,GAMZCW,TERM,SUM |
| 25 | REAL SUMBR,BRMODE,TRY,HELPL,HELMN,HEL,PZ |
| 26 | INTEGER NF,J,JTABS,IQ,IFL,IW,JT0,JT1,IFL1,IFL2 |
| 27 | INTEGER IWTYPE,JET,JW,IQ1,IQ2,JPAR,IFLPAR,NJ1,NJ2,IDABS1,IDABS2 |
| 28 | REAL GAMSAV(5),ZCSAV(5),BRANCH(25) |
| 29 | INTEGER JSAV(5),LISTW(5),LISTJ(25) |
| 30 | DATA LISTW/9,10,80,-80,90/ |
| 31 | DATA LISTJ/9,1,-1,2,-2,3,-3,4,-4,5,-5,6,-6, |
| 32 | $11,-11,12,-12,13,-13,14,-14,15,-15,16,-16/ |
| 33 | C |
| 34 | C Altarelli-Parisi functions. |
| 35 | PQQ(Z)=4*(1+Z**2)/(3*(1-Z)) |
| 36 | PGQ(Z)=.5*(Z**2+(1-Z)**2) |
| 37 | PGG(Z)=6*(1-Z*(1-Z))**2/(Z*(1-Z)) |
| 38 | PGSGS(Z)=3.*(1.+Z**2)/(1.-Z) |
| 39 | PQSQS(Z)=8./3.*Z/(1.-Z) |
| 40 | ALFAS(QQ)=12.*PI/((33.-2.*NF)*ALOG(QQ/ALAM2)) |
| 41 | C |
| 42 | C Initialize. |
| 43 | C |
| 44 | AM0=PJSET(5,J) |
| 45 | ZC=ZZC(J) |
| 46 | JTABS=IABS(JTYPE(J)) |
| 47 | NF=3 |
| 48 | DO 110 IQ=4,6 |
| 49 | IF(AM0.LT.2*AMASS(IQ)) GO TO 120 |
| 50 | NF=NF+1 |
| 51 | 110 CONTINUE |
| 52 | 120 CONTINUE |
| 53 | NJ1=NJSET+1 |
| 54 | NJ2=NJSET+2 |
| 55 | C |
| 56 | C Initial gluon |
| 57 | C |
| 58 | IF (JTABS.EQ.9) THEN |
| 59 | GAMQQ=(1-2*ZC)*(1-ZC*(1-ZC))/3. |
| 60 | GAMGG=12*ALOG((1-ZC)/ZC)-9*(1-2*ZC)-6*GAMQQ |
| 61 | PROBG=GAMGG/(GAMGG+2*NF*GAMQQ) |
| 62 | PROBQ=GAMQQ/(GAMGG+2*NF*GAMQQ) |
| 63 | RND=RANF() |
| 64 | C GL--->GL+GL |
| 65 | IF(PROBG.GT.RND) THEN |
| 66 | 130 ZGEN=(ZC/(1-ZC))**(1-2*RANF()) |
| 67 | Z=ZGEN/(1.+ZGEN) |
| 68 | GZ=6./(Z*(1.-Z)) |
| 69 | IF(PGG(Z).LT.GZ*RANF()) GO TO 130 |
| 70 | JTYPE(NJ1)=9 |
| 71 | JTYPE(NJ2)=9 |
| 72 | ZZC(J)=Z |
| 73 | C GL--->QK+QB |
| 74 | ELSE |
| 75 | 140 Z=RANF() |
| 76 | IF(PGQ(Z).LT.0.5*RANF()) GO TO 140 |
| 77 | IFL=(RND-PROBG)/PROBQ+1. |
| 78 | IF(IFL.GT.NF) IFL=NF-IFL |
| 79 | JTYPE(NJ1)=IFL |
| 80 | JTYPE(NJ2)=-IFL |
| 81 | ZZC(J)=Z |
| 82 | ENDIF |
| 83 | C |
| 84 | C Initial quark - may radiate GL, GM, W+-, Z0 |
| 85 | C |
| 86 | ELSEIF(JTABS.LT.9) THEN |
| 87 | C Gluon |
| 88 | GAMZC=2.*ALOG((1-ZC)/ZC)-1.5*(1.-2.*ZC) |
| 89 | GAMSAV(1)=4./3.*ALFAS(AM0**2)*GAMZC |
| 90 | ZCSAV(1)=ZC |
| 91 | JSAV(1)=JTYPE(J) |
| 92 | C Photon |
| 93 | GAMSAV(2)=ALFA*AQ(JTABS,1)**2*GAMZC |
| 94 | ZCSAV(2)=ZC |
| 95 | GAMSUM=GAMSAV(1)+GAMSAV(2) |
| 96 | JSAV(2)=JTYPE(J) |
| 97 | C W+- and Z0 |
| 98 | IF(AM0.GT.WMASS(4)) THEN |
| 99 | DO 200 IW=2,4 |
| 100 | GAMSAV(IW+1)=0. |
| 101 | ZCSAV(IW+1)=.5 |
| 102 | JSAV(IW+1)=0 |
| 103 | JT0=2*IABS(JTYPE(J)) |
| 104 | IF(JTYPE(J).LT.0) JT0=JT0+1 |
| 105 | JT1=MATCH(JT0,IW) |
| 106 | IF(JT1.EQ.0) GO TO 200 |
| 107 | JT1=MATCH(JT1,4) |
| 108 | IFL1=JT1/2 |
| 109 | AM1W=AMASS(IFL1) |
| 110 | AM2W=AMASS(LISTW(IW+1)) |
| 111 | IF(AM1W+AM2W.GE.AM0) GO TO 200 |
| 112 | T0=AM0**2 |
| 113 | T1W=AM1W**2 |
| 114 | T2W=AM2W**2 |
| 115 | ZCW=(T0-T1W+T2W-SQRT((T0-T1W-T2W)**2-4*T1W*T2W))/(2*T0) |
| 116 | GAMZCW=2.*ALOG((1-ZCW)/ZCW)-2.*(1.-2.*ZCW) |
| 117 | TERM=(AQ(JTABS,IW)**2+BQ(JTABS,IW)**2)*ALFA*GAMZCW |
| 118 | GAMSAV(IW+1)=TERM |
| 119 | ZCSAV(IW+1)=ZCW |
| 120 | JSAV(IW+1)=IFL1*ISIGN(1,JTYPE(J)) |
| 121 | GAMSUM=GAMSUM+TERM |
| 122 | 200 CONTINUE |
| 123 | ELSE |
| 124 | DO 210 IW=2,4 |
| 125 | GAMSAV(IW+1)=0. |
| 126 | ZCSAV(IW+1)=.5 |
| 127 | JSAV(IW+1)=0 |
| 128 | 210 CONTINUE |
| 129 | ENDIF |
| 130 | C Select decay mode |
| 131 | RND=RANF() |
| 132 | SUM=0. |
| 133 | DO 220 IW=1,5 |
| 134 | IWTYPE=IW |
| 135 | SUM=SUM+GAMSAV(IW)/GAMSUM |
| 136 | IF(RND.LT.SUM) GO TO 230 |
| 137 | 220 CONTINUE |
| 138 | C Generate Z |
| 139 | 230 CONTINUE |
| 140 | Z=1-(ZC/(1-ZC))**RANF()*(1-ZC) |
| 141 | GZ=8./(3.*(1-Z)) |
| 142 | IF(PQQ(Z).LT.GZ*RANF()) GO TO 230 |
| 143 | IF(Z.LT.ZCSAV(IWTYPE).OR.Z.GT.1.-ZCSAV(IWTYPE)) GO TO 230 |
| 144 | JTYPE(NJ1)=JSAV(IWTYPE) |
| 145 | JTYPE(NJ2)=LISTW(IWTYPE) |
| 146 | ZZC(J)=Z |
| 147 | C |
| 148 | C Initial diquark |
| 149 | C |
| 150 | ELSEIF(MOD(JTABS,100).EQ.0) THEN |
| 151 | 300 CONTINUE |
| 152 | Z=1-(ZC/(1-ZC))**RANF()*(1-ZC) |
| 153 | GZ=8./(3.*(1-Z)) |
| 154 | IF(PQQ(Z).LT.GZ*RANF()) GO TO 300 |
| 155 | JTYPE(NJ1)=JTYPE(J) |
| 156 | JTYPE(NJ2)=9 |
| 157 | ZZC(J)=Z |
| 158 | C |
| 159 | C Initial gluino |
| 160 | C |
| 161 | ELSEIF (JTABS.EQ.29) THEN |
| 162 | 400 Z=1.-(ZC/(1.-ZC))**RANF()*(1.-ZC) |
| 163 | GZ=6./(1.-Z) |
| 164 | IF(PGSGS(Z) .LT. GZ*RANF()) GOTO 400 |
| 165 | JTYPE(NJ1)=JTYPE(J) |
| 166 | JTYPE(NJ2)=9 |
| 167 | ZZC(J)=Z |
| 168 | C |
| 169 | C Initial squark |
| 170 | C |
| 171 | ELSEIF(JTABS.GT.20.AND.JTABS.LT.29) THEN |
| 172 | 500 CONTINUE |
| 173 | Z=1-(ZC/(1-ZC))**RANF()*(1-ZC) |
| 174 | GZ=8./(3.*(1-Z)) |
| 175 | IF(PQSQS(Z).LT.GZ*RANF()) GO TO 500 |
| 176 | JTYPE(NJ1)=JTYPE(J) |
| 177 | JTYPE(NJ2)=9 |
| 178 | ZZC(J)=Z |
| 179 | C |
| 180 | C Initial W+, W-, or Z0 |
| 181 | C |
| 182 | ELSEIF(JTABS.EQ.80.OR.JTABS.EQ.90) THEN |
| 183 | C Select decay mode |
| 184 | IF(JTYPE(J).EQ.+80) JW=2 |
| 185 | IF(JTYPE(J).EQ.-80) JW=3 |
| 186 | IF(JTYPE(J).EQ.+90) JW=4 |
| 187 | TRY=RANF() |
| 188 | DO 610 IQ=2,25 |
| 189 | IF(TRY.LT.CUMWBR(IQ,JW-1)) THEN |
| 190 | IQ1=IQ |
| 191 | IQ2=MATCH(IQ,JW) |
| 192 | GO TO 620 |
| 193 | ENDIF |
| 194 | 610 CONTINUE |
| 195 | 620 JTYPE(NJ1)=LISTJ(IQ1) |
| 196 | JTYPE(NJ2)=LISTJ(IQ2) |
| 197 | C Select W helicity |
| 198 | JPAR=MOD(JORIG(J),JPACK) |
| 199 | IFLPAR=IABS(JTYPE(JPAR)) |
| 200 | HELPL=(AQ(IFLPAR,JW)-BQ(IFLPAR,JW))**2 |
| 201 | HELMN=(AQ(IFLPAR,JW)+BQ(IFLPAR,JW))**2 |
| 202 | IF(RANF()*(HELPL+HELMN).LT.HELMN) THEN |
| 203 | HEL=-ISIGN(1,JTYPE(NJ1)) |
| 204 | ELSE |
| 205 | HEL=+ISIGN(1,JTYPE(NJ1)) |
| 206 | ENDIF |
| 207 | 630 Z=RANF() |
| 208 | PZ=(1.+HEL*(2.*Z-1.))**2 |
| 209 | IF(PZ.LT.4.*RANF()) GO TO 630 |
| 210 | ZZC(J)=Z |
| 211 | ENDIF |
| 212 | C |
| 213 | C Set masses and flags. |
| 214 | C |
| 215 | JET=IABS(JORIG(J))/JPACK |
| 216 | JORIG(NJ1)=JPACK*JET+J |
| 217 | JORIG(NJ2)=JPACK*JET+J |
| 218 | IDABS1=IABS(JTYPE(NJ1)) |
| 219 | IDABS2=IABS(JTYPE(NJ2)) |
| 220 | JMATCH(NJ1)=NJ2 |
| 221 | JMATCH(NJ2)=NJ1 |
| 222 | C JDCAY=-1 implies further decay |
| 223 | IF(IDABS1.LE.9.OR.(IDABS1.GT.20.AND.IDABS1.LT.30.).OR. |
| 224 | $MOD(IDABS1,100).EQ.0) THEN |
| 225 | PJSET(5,NJ1)=Z*AM0 |
| 226 | JDCAY(NJ1)=-1 |
| 227 | ELSEIF(IDABS1.GE.80.OR.IDABS1.LE.90) THEN |
| 228 | PJSET(5,NJ1)=AMASS(IDABS1) |
| 229 | JDCAY(NJ1)=-1 |
| 230 | ELSE |
| 231 | PJSET(5,NJ1)=AMASS(IDABS1) |
| 232 | JDCAY(NJ1)=0 |
| 233 | ENDIF |
| 234 | IF(IDABS2.LE.9.OR.(IDABS2.GT.20.AND.IDABS2.LT.30.).OR. |
| 235 | $MOD(IDABS2,100).EQ.0) THEN |
| 236 | PJSET(5,NJ2)=(1.-Z)*AM0 |
| 237 | JDCAY(NJ2)=-1 |
| 238 | ELSEIF(IDABS2.EQ.80.OR.IDABS2.EQ.90) THEN |
| 239 | PJSET(5,NJ2)=AMASS(IDABS2) |
| 240 | JDCAY(NJ2)=-1 |
| 241 | ELSE |
| 242 | PJSET(5,NJ2)=AMASS(IDABS2) |
| 243 | JDCAY(NJ2)=0 |
| 244 | ENDIF |
| 245 | RETURN |
| 246 | END |
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