| 3820ca8e |
1 | |
| 2 | CDECK ID>, HWHIGZ. |
| 3 | |
| 4 | *CMZ :- -02/05/91 11.18.44 by Federico Carminati |
| 5 | |
| 6 | *-- Author : Mike Seymour |
| 7 | |
| 8 | C----------------------------------------------------------------------- |
| 9 | |
| 10 | SUBROUTINE HWHIGZ |
| 11 | |
| 12 | C----------------------------------------------------------------------- |
| 13 | |
| 14 | C HIGGS PRODUCTION VIA THE BJORKEN PROCESS: E+E- --> Z(*) --> Z(*)H |
| 15 | |
| 16 | C WHERE ONE OR BOTH OF THE Zs IS OFF-SHELL |
| 17 | |
| 18 | C USES ALGORITHM OF BERENDS AND KLEISS: NUCL.PHYS. B260(1985)32 |
| 19 | |
| 20 | C |
| 21 | |
| 22 | C MEAN EVWGT = CROSS-SECTION (IN NB) * HIGGS BRANCHING FRACTION |
| 23 | |
| 24 | C----------------------------------------------------------------------- |
| 25 | |
| 26 | INCLUDE 'HERWIG61.INC' |
| 27 | |
| 28 | DOUBLE PRECISION HWUAEM,HWHIGY,HWRUNI,HWR,HWULDO,EMZ,CVE,CAE, |
| 29 | |
| 30 | & POL1,POL2,CE1,CE2,CE3,PMAX,EMZ2,S,B,FACTR,EMH,EMFAC,EMH2,A,XP, |
| 31 | |
| 32 | & CV,CA,BRHIGQ,BR,X1,X2,FAC1,FAC2,XPP,XPPSQ,COEF,X,XSQ,PROB,C1,C2, |
| 33 | |
| 34 | & CHIGG,PTHETA,SHIGG,C3,PHIMAX,CPHI,SPHI,C2PHI,S2PHI,PCM,ELST |
| 35 | |
| 36 | INTEGER IDEC,I,NLOOP,ICMF,IHIG,IZED,IFER,IANT,ID1,ID2,IN1,IN2 |
| 37 | |
| 38 | EXTERNAL HWUAEM,HWHIGY,HWRUNI,HWR,HWULDO |
| 39 | |
| 40 | SAVE CVE,CAE,CE1,CE2,CE3,PMAX,EMZ2,S,EMH,B,FACTR,A,EMH2 |
| 41 | |
| 42 | EQUIVALENCE (EMZ,RMASS(200)) |
| 43 | |
| 44 | DATA ELST/0/ |
| 45 | |
| 46 | C---SET UP CONSTANTS |
| 47 | |
| 48 | IN1=1 |
| 49 | |
| 50 | IF (JDAHEP(1,IN1).NE.0) IN1=JDAHEP(1,IN1) |
| 51 | |
| 52 | IN2=2 |
| 53 | |
| 54 | IF (JDAHEP(1,IN2).NE.0) IN2=JDAHEP(1,IN2) |
| 55 | |
| 56 | IF (FSTWGT.OR.ELST.NE.PHEP(5,3)) THEN |
| 57 | |
| 58 | ELST=PHEP(5,3) |
| 59 | |
| 60 | CVE=VFCH(11,1) |
| 61 | |
| 62 | CAE=AFCH(11,1) |
| 63 | |
| 64 | POL1=1.-EPOLN(3)*PPOLN(3) |
| 65 | |
| 66 | POL2=EPOLN(3)-PPOLN(3) |
| 67 | |
| 68 | CE1=(POL1*(CVE**2+CAE**2)+POL2*2.*CVE*CAE) |
| 69 | |
| 70 | CE2=(POL1*2.*CVE*CAE+POL2*(CVE**2+CAE**2)) |
| 71 | |
| 72 | IF ((IDHW(IN1).GT.IDHW(IN2).AND.PHEP(3,IN1).LT.ZERO).OR. |
| 73 | |
| 74 | & (IDHW(IN2).GT.IDHW(IN1).AND.PHEP(3,IN2).LT.ZERO)) CE2=-CE2 |
| 75 | |
| 76 | IF (TPOL) CE3=(CVE**2-CAE**2) |
| 77 | |
| 78 | PMAX=4 |
| 79 | |
| 80 | EMZ2=EMZ**2 |
| 81 | |
| 82 | S=PHEP(5,3)**2 |
| 83 | |
| 84 | B=EMZ*GAMZ/S |
| 85 | |
| 86 | FACTR=GEV2NB*CE1*(HWUAEM(RMASS(201)**2)*ENHANC(11))**2 |
| 87 | |
| 88 | & /(12.*S*SWEIN*(1.-SWEIN))*B/((1-EMZ2/S)**2+B**2) |
| 89 | |
| 90 | ENDIF |
| 91 | |
| 92 | IF (.NOT.GENEV) THEN |
| 93 | |
| 94 | C---CHOOSE HIGGS MASS, AND CALCULATE EVENT WEIGHT |
| 95 | |
| 96 | EVWGT=0D0 |
| 97 | |
| 98 | CALL HWHIGM(EMH,EMFAC) |
| 99 | |
| 100 | IF (EMH.LE.ZERO .OR. EMH.GT.PHEP(5,3)) RETURN |
| 101 | |
| 102 | EMSCA=EMH |
| 103 | |
| 104 | EMH2=EMH**2 |
| 105 | |
| 106 | A=4*EMH2/S |
| 107 | |
| 108 | XP=1+(EMH2-EMZ2)/S |
| 109 | |
| 110 | EVWGT=FACTR*HWHIGY(A,B,XP)*EMFAC |
| 111 | |
| 112 | C---INCLUDE BRANCHING RATIO OF HIGGS |
| 113 | |
| 114 | IDEC=MOD(IPROC,100) |
| 115 | |
| 116 | IF (IDEC.GT.0.AND.IDEC.LE.12) EVWGT=EVWGT*BRHIG(IDEC) |
| 117 | |
| 118 | IF (IDEC.EQ.0) THEN |
| 119 | |
| 120 | BRHIGQ=0 |
| 121 | |
| 122 | DO 10 I=1,6 |
| 123 | |
| 124 | 10 BRHIGQ=BRHIGQ+BRHIG(I) |
| 125 | |
| 126 | EVWGT=EVWGT*BRHIGQ |
| 127 | |
| 128 | ENDIF |
| 129 | |
| 130 | C Add Z branching fractions |
| 131 | |
| 132 | CALL HWDBOZ(200,ID1,ID2,CV,CA,BR,0) |
| 133 | |
| 134 | EVWGT=EVWGT*BR |
| 135 | |
| 136 | IF (IDEC.EQ.10) THEN |
| 137 | |
| 138 | CALL HWDBOZ(198,ID1,ID2,CV,CA,BR,1) |
| 139 | |
| 140 | CALL HWDBOZ(199,ID1,ID2,CV,CA,BR,1) |
| 141 | |
| 142 | EVWGT=EVWGT*BR |
| 143 | |
| 144 | ELSEIF (IDEC.EQ.11) THEN |
| 145 | |
| 146 | CALL HWDBOZ(200,ID1,ID2,CV,CA,BR,1) |
| 147 | |
| 148 | CALL HWDBOZ(200,ID1,ID2,CV,CA,BR,1) |
| 149 | |
| 150 | EVWGT=EVWGT*BR |
| 151 | |
| 152 | ENDIF |
| 153 | |
| 154 | ELSE |
| 155 | |
| 156 | C---GENERATE EVENT |
| 157 | |
| 158 | ICMF=NHEP+1 |
| 159 | |
| 160 | IHIG=NHEP+2 |
| 161 | |
| 162 | IZED=NHEP+3 |
| 163 | |
| 164 | IFER=NHEP+4 |
| 165 | |
| 166 | IANT=NHEP+5 |
| 167 | |
| 168 | CALL HWVEQU(5,PHEP(1,3),PHEP(1,ICMF)) |
| 169 | |
| 170 | NHEP=NHEP+5 |
| 171 | |
| 172 | C---CHOOSE ENERGY FRACTION OF HIGGS |
| 173 | |
| 174 | X1=SQRT(A) |
| 175 | |
| 176 | X2=1+0.25*A |
| 177 | |
| 178 | XP=1+(EMH2-EMZ2)/S |
| 179 | |
| 180 | FAC1=ATAN((X1-XP)/B) |
| 181 | |
| 182 | FAC2=ATAN((X2-XP)/B) |
| 183 | |
| 184 | XPP=MIN(X2,MAX(X1+B,XP)) |
| 185 | |
| 186 | XPPSQ=XPP**2 |
| 187 | |
| 188 | NLOOP=0 |
| 189 | |
| 190 | COEF=1./((12+2*A-12*XPP+XPPSQ)*SQRT(XPPSQ-A)) |
| 191 | |
| 192 | 20 NLOOP=NLOOP+1 |
| 193 | |
| 194 | IF (NLOOP.GT.NBTRY) CALL HWWARN('HWHIGZ',101,*999) |
| 195 | |
| 196 | X=XP+B*TAN(HWRUNI(1,FAC1,FAC2)) |
| 197 | |
| 198 | XSQ=X**2 |
| 199 | |
| 200 | PROB=COEF*((12+2*A-12*X+XSQ)*SQRT(XSQ-A)) |
| 201 | |
| 202 | IF (PROB.GT.PMAX) THEN |
| 203 | |
| 204 | PMAX=1.1*PROB |
| 205 | |
| 206 | CALL HWWARN('HWHIGZ',1,*999) |
| 207 | |
| 208 | WRITE (6,21) PMAX |
| 209 | |
| 210 | 21 FORMAT(7X,'NEW HWHIGZ MAX WEIGHT =',F8.4) |
| 211 | |
| 212 | ENDIF |
| 213 | |
| 214 | IF (PROB.LT.PMAX*HWR()) GOTO 20 |
| 215 | |
| 216 | C Choose Z decay mode |
| 217 | |
| 218 | CALL HWDBOZ(200,IDHW(IFER),IDHW(IANT),CV,CA,BR,0) |
| 219 | |
| 220 | C1=CE1*(CV**2+CA**2) |
| 221 | |
| 222 | C2=CE2*2.*CV*CA |
| 223 | |
| 224 | C---CHOOSE HIGGS DIRECTION |
| 225 | |
| 226 | C First polar angle |
| 227 | |
| 228 | NLOOP=0 |
| 229 | |
| 230 | COEF=(XSQ-A)/(8.*(1.-X)+XSQ+A) |
| 231 | |
| 232 | 30 NLOOP=NLOOP+1 |
| 233 | |
| 234 | IF (NLOOP.GT.NBTRY) CALL HWWARN('HWHIGZ',102,*999) |
| 235 | |
| 236 | CHIGG=HWRUNI(2,-ONE, ONE) |
| 237 | |
| 238 | PTHETA=1-COEF*CHIGG**2 |
| 239 | |
| 240 | IF (PTHETA.LT.HWR()) GOTO 30 |
| 241 | |
| 242 | SHIGG=SQRT(1-CHIGG**2) |
| 243 | |
| 244 | C Now azimuthal angle |
| 245 | |
| 246 | IF (TPOL) THEN |
| 247 | |
| 248 | C3=CE3*(CV*2+CA**2) |
| 249 | |
| 250 | COEF=COEF*SHIGG**2*C3/C1 |
| 251 | |
| 252 | PHIMAX=PTHETA+ABS(COEF) |
| 253 | |
| 254 | 40 CALL HWRAZM(ONE,CPHI,SPHI) |
| 255 | |
| 256 | C2PHI=2.*CPHI**2-1. |
| 257 | |
| 258 | S2PHI=2.*CPHI*SPHI |
| 259 | |
| 260 | PROB=PTHETA-COEF*(C2PHI*COSS+S2PHI*SINS) |
| 261 | |
| 262 | IF (PROB.LT.HWR()*PHIMAX) GOTO 40 |
| 263 | |
| 264 | ELSE |
| 265 | |
| 266 | CALL HWRAZM(ONE,CPHI,SPHI) |
| 267 | |
| 268 | ENDIF |
| 269 | |
| 270 | C Construct Higgs and Z momenta |
| 271 | |
| 272 | PHEP(5,IHIG)=EMH |
| 273 | |
| 274 | PHEP(4,IHIG)=X*PHEP(5,ICMF)/2 |
| 275 | |
| 276 | PCM=SQRT(PHEP(4,IHIG)**2-EMH2) |
| 277 | |
| 278 | PHEP(3,IHIG)=CHIGG*PCM |
| 279 | |
| 280 | PHEP(1,IHIG)=SHIGG*PCM*CPHI |
| 281 | |
| 282 | PHEP(2,IHIG)=SHIGG*PCM*SPHI |
| 283 | |
| 284 | CALL HWVDIF(4,PHEP(1,ICMF),PHEP(1,IHIG),PHEP(1,IZED)) |
| 285 | |
| 286 | CALL HWUMAS(PHEP(1,IZED)) |
| 287 | |
| 288 | C Choose orientation of Z decay |
| 289 | |
| 290 | NLOOP=0 |
| 291 | |
| 292 | COEF=2.*(C1+ABS(C2))*HWULDO(PHEP(1,IN1),PHEP(1,IZED)) |
| 293 | |
| 294 | & *HWULDO(PHEP(1,IN2),PHEP(1,IZED))/S |
| 295 | |
| 296 | IF (TPOL) COEF=COEF*(C1+ABS(C2)+ABS(C3))/(C1+ABS(C2)) |
| 297 | |
| 298 | PCM=PHEP(5,IZED)/2 |
| 299 | |
| 300 | PHEP(5,IFER)=0 |
| 301 | |
| 302 | PHEP(5,IANT)=0 |
| 303 | |
| 304 | 50 NLOOP=NLOOP+1 |
| 305 | |
| 306 | IF (NLOOP.GT.NBTRY) CALL HWWARN('HWHIGZ',103,*999) |
| 307 | |
| 308 | CALL HWDTWO(PHEP(1,IZED),PHEP(1,IFER),PHEP(1,IANT), |
| 309 | |
| 310 | & PCM,TWO,.TRUE.) |
| 311 | |
| 312 | PROB=C1*(PHEP(4,IFER)*PHEP(4,IANT)-PHEP(3,IFER)*PHEP(3,IANT)) |
| 313 | |
| 314 | & +C2*(PHEP(4,IFER)*PHEP(3,IANT)-PHEP(3,IFER)*PHEP(4,IANT)) |
| 315 | |
| 316 | IF (TPOL) PROB=PROB+C3* |
| 317 | |
| 318 | & (COSS*(PHEP(1,IFER)*PHEP(1,IANT)-PHEP(2,IFER)*PHEP(2,IANT)) |
| 319 | |
| 320 | & +SINS*(PHEP(1,IFER)*PHEP(2,IANT)+PHEP(2,IFER)*PHEP(1,IANT))) |
| 321 | |
| 322 | IF (PROB.LT.HWR()*COEF) GOTO 50 |
| 323 | |
| 324 | C---SET UP STATUS CODES, |
| 325 | |
| 326 | ISTHEP(ICMF)=120 |
| 327 | |
| 328 | ISTHEP(IHIG)=190 |
| 329 | |
| 330 | ISTHEP(IZED)=195 |
| 331 | |
| 332 | ISTHEP(IFER)=113 |
| 333 | |
| 334 | ISTHEP(IANT)=114 |
| 335 | |
| 336 | C---COLOR CONNECTIONS, |
| 337 | |
| 338 | JMOHEP(1,ICMF)=1 |
| 339 | |
| 340 | JMOHEP(2,ICMF)=2 |
| 341 | |
| 342 | JDAHEP(1,ICMF)=IHIG |
| 343 | |
| 344 | JDAHEP(2,ICMF)=IZED |
| 345 | |
| 346 | JMOHEP(1,IHIG)=ICMF |
| 347 | |
| 348 | JMOHEP(1,IZED)=ICMF |
| 349 | |
| 350 | JMOHEP(1,IFER)=IZED |
| 351 | |
| 352 | JMOHEP(1,IANT)=IZED |
| 353 | |
| 354 | JMOHEP(2,IFER)=IANT |
| 355 | |
| 356 | JMOHEP(2,IANT)=IFER |
| 357 | |
| 358 | JDAHEP(1,IZED)=IFER |
| 359 | |
| 360 | JDAHEP(2,IZED)=IANT |
| 361 | |
| 362 | JDAHEP(2,IFER)=IANT |
| 363 | |
| 364 | JDAHEP(2,IANT)=IFER |
| 365 | |
| 366 | C---IDENTITY CODES |
| 367 | |
| 368 | IDHW(ICMF)=200 |
| 369 | |
| 370 | IDHW(IHIG)=201 |
| 371 | |
| 372 | IDHW(IZED)=200 |
| 373 | |
| 374 | IDHEP(ICMF)=IDPDG(IDHW(ICMF)) |
| 375 | |
| 376 | IDHEP(IHIG)=IDPDG(IDHW(IHIG)) |
| 377 | |
| 378 | IDHEP(IZED)=IDPDG(IDHW(IZED)) |
| 379 | |
| 380 | IDHEP(IFER)=IDPDG(IDHW(IFER)) |
| 381 | |
| 382 | IDHEP(IANT)=IDPDG(IDHW(IANT)) |
| 383 | |
| 384 | ENDIF |
| 385 | |
| 386 | 999 END |
| 387 | |
| 388 | CDECK ID>, HWHPH2. |
| 389 | |
| 390 | *CMZ :- -12/01/93 10.12.43 by Bryan Webber |
| 391 | |
| 392 | *-- Author : Ian Knowles |
| 393 | |
| 394 | C----------------------------------------------------------------------- |
| 395 | |
| 396 | SUBROUTINE HWHPH2 |
| 397 | |
| 398 | C----------------------------------------------------------------------- |
| 399 | |
| 400 | C QQD direct photon pair production: mean EVWGT = sigma in nb |
| 401 | |
| 402 | C----------------------------------------------------------------------- |
| 403 | |
| 404 | INCLUDE 'HERWIG61.INC' |
| 405 | |
| 406 | DOUBLE PRECISION HWR,HWRUNI,HWUALF,HWHPPB,EPS,RCS,ET,EJ,KK,KK2, |
| 407 | |
| 408 | & YJ1INF,YJ1SUP,Z1,YJ2INF,YJ2SUP,Z2,FACT,FACTR,RS,S,T,U,CSTU,TQSQ, |
| 409 | |
| 410 | & DSTU,HCS |
| 411 | |
| 412 | INTEGER ID,ID1,ID2 |
| 413 | |
| 414 | EXTERNAL HWR,HWRUNI,HWUALF,HWHPPB |
| 415 | |
| 416 | SAVE HCS,CSTU,DSTU,FACT |
| 417 | |
| 418 | PARAMETER (EPS=1.D-9) |
| 419 | |
| 420 | IF (GENEV) THEN |
| 421 | |
| 422 | RCS=HCS*HWR() |
| 423 | |
| 424 | ELSE |
| 425 | |
| 426 | EVWGT=0. |
| 427 | |
| 428 | CALL HWRPOW(ET,EJ) |
| 429 | |
| 430 | KK=ET/PHEP(5,3) |
| 431 | |
| 432 | KK2=KK**2 |
| 433 | |
| 434 | IF (KK.GE.ONE) RETURN |
| 435 | |
| 436 | YJ1INF=MAX( YJMIN , LOG((1.-SQRT(1.-KK2))/KK) ) |
| 437 | |
| 438 | YJ1SUP=MIN( YJMAX , LOG((1.+SQRT(1.-KK2))/KK) ) |
| 439 | |
| 440 | IF (YJ1INF.GE.YJ1SUP) RETURN |
| 441 | |
| 442 | Z1=EXP(HWRUNI(1,YJ1INF,YJ1SUP)) |
| 443 | |
| 444 | YJ2INF=MAX( YJMIN , -LOG(2./KK-1./Z1) ) |
| 445 | |
| 446 | YJ2SUP=MIN( YJMAX , LOG(2./KK-Z1) ) |
| 447 | |
| 448 | IF (YJ2INF.GE.YJ2SUP) RETURN |
| 449 | |
| 450 | Z2=EXP(HWRUNI(2,YJ2INF,YJ2SUP)) |
| 451 | |
| 452 | XX(1)=0.5*(Z1+Z2)*KK |
| 453 | |
| 454 | IF (XX(1).GE.ONE) RETURN |
| 455 | |
| 456 | XX(2)=XX(1)/(Z1*Z2) |
| 457 | |
| 458 | IF (XX(2).GE.ONE) RETURN |
| 459 | |
| 460 | COSTH=(Z1-Z2)/(Z1+Z2) |
| 461 | |
| 462 | S=XX(1)*XX(2)*PHEP(5,3)**2 |
| 463 | |
| 464 | RS=0.5*SQRT(S) |
| 465 | |
| 466 | T=-0.5*S*(1.-COSTH) |
| 467 | |
| 468 | U=-S-T |
| 469 | |
| 470 | EMSCA=SQRT(2.*S*T*U/(S*S+T*T+U*U)) |
| 471 | |
| 472 | FACT=GEV2NB*PIFAC*0.5*ET*EJ*(YJ1SUP-YJ1INF)*(YJ2SUP-YJ2INF) |
| 473 | |
| 474 | & *(ALPHEM/S)**2 |
| 475 | |
| 476 | CALL HWSGEN(.FALSE.) |
| 477 | |
| 478 | CSTU=2.*(U/T+T/U)/CAFAC |
| 479 | |
| 480 | IF (DISF(13,1).GT.EPS.AND.DISF(13,2).GT.EPS) THEN |
| 481 | |
| 482 | TQSQ=0. |
| 483 | |
| 484 | DO 10 ID=1,6 |
| 485 | |
| 486 | 10 IF (RMASS(ID).LT.RS) TQSQ=TQSQ+QFCH(ID)**2 |
| 487 | |
| 488 | DSTU=DISF(13,1)*DISF(13,2)*FACT*HWHPPB(S,T,U) |
| 489 | |
| 490 | & /64.*(HWUALF(1,EMSCA)*TQSQ/PIFAC)**2 |
| 491 | |
| 492 | ENDIF |
| 493 | |
| 494 | ENDIF |
| 495 | |
| 496 | HCS=0. |
| 497 | |
| 498 | DO 30 ID=1,6 |
| 499 | |
| 500 | FACTR=FACT*CSTU*QFCH(ID)**4 |
| 501 | |
| 502 | C q+qbar ---> gamma+gamma |
| 503 | |
| 504 | ID1=ID |
| 505 | |
| 506 | ID2=ID+6 |
| 507 | |
| 508 | IF (DISF(ID1,1).LT.EPS.OR.DISF(ID2,2).LT.EPS) GOTO 20 |
| 509 | |
| 510 | HCS=HCS+FACTR*DISF(ID1,1)*DISF(ID2,2) |
| 511 | |
| 512 | IF (GENEV.AND.HCS.GT.RCS) CALL HWHQCP(59,59,2134,61,*99) |
| 513 | |
| 514 | C qbar+q ---> gamma+gamma |
| 515 | |
| 516 | 20 ID1=ID+6 |
| 517 | |
| 518 | ID2=ID |
| 519 | |
| 520 | IF (DISF(ID1,1).LT.EPS.OR.DISF(ID2,2).LT.EPS) GOTO 30 |
| 521 | |
| 522 | HCS=HCS+FACTR*DISF(ID1,1)*DISF(ID2,2) |
| 523 | |
| 524 | IF (GENEV.AND.HCS.GT.RCS) CALL HWHQCP(59,59,2134,62,*99) |
| 525 | |
| 526 | 30 CONTINUE |
| 527 | |
| 528 | C g+g ---> gamma+gamma |
| 529 | |
| 530 | ID1=13 |
| 531 | |
| 532 | ID2=13 |
| 533 | |
| 534 | HCS=HCS+DSTU |
| 535 | |
| 536 | IF (GENEV.AND.HCS.GT.RCS) CALL HWHQCP(59,59,2134,63,*99) |
| 537 | |
| 538 | EVWGT=HCS |
| 539 | |
| 540 | RETURN |
| 541 | |
| 542 | C Generate event |
| 543 | |
| 544 | 99 IDN(1)=ID1 |
| 545 | |
| 546 | IDN(2)=ID2 |
| 547 | |
| 548 | IDCMF=15 |
| 549 | |
| 550 | CALL HWETWO |
| 551 | |
| 552 | 999 END |
| 553 | |
| 554 | CDECK ID>, HWHPHO. |
| 555 | |
| 556 | *CMZ :- -26/04/91 14.55.45 by Federico Carminati |
| 557 | |
| 558 | *-- Author : Bryan Webber |
| 559 | |
| 560 | C----------------------------------------------------------------------- |
| 561 | |
| 562 | SUBROUTINE HWHPHO |
| 563 | |
| 564 | C----------------------------------------------------------------------- |
| 565 | |
| 566 | C QCD DIRECT PHOTON + JET PRODUCTION: MEAN EVWGT = SIGMA IN NB |
| 567 | |
| 568 | C----------------------------------------------------------------------- |
| 569 | |
| 570 | INCLUDE 'HERWIG61.INC' |
| 571 | |
| 572 | DOUBLE PRECISION HWR,HWRUNI,HWUALF,HWHPPB,EPS,RCS,ET,EJ,KK,KK2, |
| 573 | |
| 574 | & YJ1INF,YJ1SUP,Z1,YJ2INF,YJ2SUP,Z2,FACT,FACTR,FACTF,RS,S,T,U,CF, |
| 575 | |
| 576 | & AF,CSTU,CTSU,CUST,DSTU,HCS,TQCH |
| 577 | |
| 578 | INTEGER ID,ID1,ID2 |
| 579 | |
| 580 | EXTERNAL HWR,HWRUNI,HWUALF,HWHPPB |
| 581 | |
| 582 | SAVE HCS |
| 583 | |
| 584 | PARAMETER (EPS=1.D-9) |
| 585 | |
| 586 | IF (GENEV) THEN |
| 587 | |
| 588 | RCS=HCS*HWR() |
| 589 | |
| 590 | ELSE |
| 591 | |
| 592 | EVWGT=0. |
| 593 | |
| 594 | CALL HWRPOW(ET,EJ) |
| 595 | |
| 596 | KK=ET/PHEP(5,3) |
| 597 | |
| 598 | KK2=KK**2 |
| 599 | |
| 600 | IF (KK.GE.ONE) RETURN |
| 601 | |
| 602 | YJ1INF=MAX( YJMIN , LOG((1.-SQRT(1.-KK2))/KK) ) |
| 603 | |
| 604 | YJ1SUP=MIN( YJMAX , LOG((1.+SQRT(1.-KK2))/KK) ) |
| 605 | |
| 606 | IF (YJ1INF.GE.YJ1SUP) RETURN |
| 607 | |
| 608 | Z1=EXP(HWRUNI(1,YJ1INF,YJ1SUP)) |
| 609 | |
| 610 | YJ2INF=MAX( YJMIN , -LOG(2./KK-1./Z1) ) |
| 611 | |
| 612 | YJ2SUP=MIN( YJMAX , LOG(2./KK-Z1) ) |
| 613 | |
| 614 | IF (YJ2INF.GE.YJ2SUP) RETURN |
| 615 | |
| 616 | Z2=EXP(HWRUNI(2,YJ2INF,YJ2SUP)) |
| 617 | |
| 618 | XX(1)=0.5*(Z1+Z2)*KK |
| 619 | |
| 620 | IF (XX(1).GE.ONE) RETURN |
| 621 | |
| 622 | XX(2)=XX(1)/(Z1*Z2) |
| 623 | |
| 624 | IF (XX(2).GE.ONE) RETURN |
| 625 | |
| 626 | COSTH=(Z1-Z2)/(Z1+Z2) |
| 627 | |
| 628 | S=XX(1)*XX(2)*PHEP(5,3)**2 |
| 629 | |
| 630 | RS=0.5*SQRT(S) |
| 631 | |
| 632 | T=-0.5*S*(1.-COSTH) |
| 633 | |
| 634 | U=-S-T |
| 635 | |
| 636 | C---SET EMSCA TO HARD PROCESS SCALE (APPROX ET-JET) |
| 637 | |
| 638 | EMSCA=SQRT(2.*S*T*U/(S*S+T*T+U*U)) |
| 639 | |
| 640 | FACT=GEV2NB*PIFAC*0.5*ET*EJ*ALPHEM |
| 641 | |
| 642 | & *HWUALF(1,EMSCA)*(YJ1SUP-YJ1INF)*(YJ2SUP-YJ2INF)/S**2 |
| 643 | |
| 644 | CALL HWSGEN(.FALSE.) |
| 645 | |
| 646 | C |
| 647 | |
| 648 | CF=2.*CFFAC/CAFAC |
| 649 | |
| 650 | AF=-1./CAFAC |
| 651 | |
| 652 | CSTU=CF*(U/T+T/U) |
| 653 | |
| 654 | CTSU=AF*(U/S+S/U) |
| 655 | |
| 656 | CUST=AF*(T/S+S/T) |
| 657 | |
| 658 | IF (DISF(13,1).GT.EPS.AND.DISF(13,2).GT.EPS) THEN |
| 659 | |
| 660 | TQCH=0. |
| 661 | |
| 662 | DO 10 ID=1,6 |
| 663 | |
| 664 | 10 IF (RMASS(ID).LT.RS) TQCH=TQCH+QFCH(ID) |
| 665 | |
| 666 | DSTU=DISF(13,1)*DISF(13,2)*FACT*HWHPPB(S,T,U) |
| 667 | |
| 668 | & *5./768.*(HWUALF(1,EMSCA)*TQCH/PIFAC)**2 |
| 669 | |
| 670 | ENDIF |
| 671 | |
| 672 | ENDIF |
| 673 | |
| 674 | C |
| 675 | |
| 676 | HCS=0. |
| 677 | |
| 678 | DO 30 ID=1,6 |
| 679 | |
| 680 | FACTR=FACT*QFCH(ID)**2 |
| 681 | |
| 682 | C---QUARK FIRST |
| 683 | |
| 684 | ID1=ID |
| 685 | |
| 686 | IF (DISF(ID1,1).LT.EPS) GOTO 20 |
| 687 | |
| 688 | ID2=ID1+6 |
| 689 | |
| 690 | HCS=HCS+CSTU*FACTR*DISF(ID1,1)*DISF(ID2,2) |
| 691 | |
| 692 | IF (GENEV.AND.HCS.GT.RCS) CALL HWHQCP( 13, 59,2314,41,*9) |
| 693 | |
| 694 | ID2=13 |
| 695 | |
| 696 | HCS=HCS+CTSU*FACTR*DISF(ID1,1)*DISF(ID2,2) |
| 697 | |
| 698 | IF (GENEV.AND.HCS.GT.RCS) CALL HWHQCP(ID1, 59,3124,42,*9) |
| 699 | |
| 700 | C---QBAR FIRST |
| 701 | |
| 702 | 20 ID1=ID+6 |
| 703 | |
| 704 | IF (DISF(ID1,1).LT.EPS) GOTO 30 |
| 705 | |
| 706 | ID2=ID |
| 707 | |
| 708 | HCS=HCS+CSTU*FACTR*DISF(ID1,1)*DISF(ID2,2) |
| 709 | |
| 710 | IF (GENEV.AND.HCS.GT.RCS) CALL HWHQCP( 13, 59,3124,43,*9) |
| 711 | |
| 712 | ID2=13 |
| 713 | |
| 714 | HCS=HCS+CTSU*FACTR*DISF(ID1,1)*DISF(ID2,2) |
| 715 | |
| 716 | IF (GENEV.AND.HCS.GT.RCS) CALL HWHQCP(ID1, 59,2314,44,*9) |
| 717 | |
| 718 | 30 CONTINUE |
| 719 | |
| 720 | C---GLUON FIRST |
| 721 | |
| 722 | ID1=13 |
| 723 | |
| 724 | FACTF=FACT*CUST*DISF(ID1,1) |
| 725 | |
| 726 | DO 50 ID=1,6 |
| 727 | |
| 728 | FACTR=FACTF*QFCH(ID)**2 |
| 729 | |
| 730 | ID2=ID |
| 731 | |
| 732 | IF (DISF(ID2,2).LT.EPS) GOTO 40 |
| 733 | |
| 734 | HCS=HCS+FACTR*DISF(ID2,2) |
| 735 | |
| 736 | IF (GENEV.AND.HCS.GT.RCS) CALL HWHQCP(ID2, 59,2314,45,*9) |
| 737 | |
| 738 | 40 ID2=ID+6 |
| 739 | |
| 740 | IF (DISF(ID2,2).LT.EPS) GOTO 50 |
| 741 | |
| 742 | HCS=HCS+FACTR*DISF(ID2,2) |
| 743 | |
| 744 | IF (GENEV.AND.HCS.GT.RCS) CALL HWHQCP(ID2, 59,3124,46,*9) |
| 745 | |
| 746 | 50 CONTINUE |
| 747 | |
| 748 | C g+g ---> g+gamma |
| 749 | |
| 750 | ID2=13 |
| 751 | |
| 752 | HCS=HCS+DSTU |
| 753 | |
| 754 | IF (GENEV.AND.HCS.GT.RCS) CALL HWHQCP( 13, 59,2314,47,*9) |
| 755 | |
| 756 | EVWGT=HCS |
| 757 | |
| 758 | RETURN |
| 759 | |
| 760 | C---GENERATE EVENT |
| 761 | |
| 762 | 9 IDN(1)=ID1 |
| 763 | |
| 764 | IDN(2)=ID2 |
| 765 | |
| 766 | IDCMF=15 |
| 767 | |
| 768 | CALL HWETWO |
| 769 | |
| 770 | 999 END |
| 771 | |
| 772 | CDECK ID>, HWHPPB. |
| 773 | |
| 774 | *CMZ :- -12/01/93 10.12.43 by Bryan Webber |
| 775 | |
| 776 | *-- Author : Ian Knowles |
| 777 | |
| 778 | C----------------------------------------------------------------------- |
| 779 | |
| 780 | FUNCTION HWHPPB(S,T,U) |
| 781 | |
| 782 | C----------------------------------------------------------------------- |
| 783 | |
| 784 | C Quark box diagram contribution to photon/gluon scattering |
| 785 | |
| 786 | C Internal quark mass neglected: m_q << U,T,S |
| 787 | |
| 788 | C----------------------------------------------------------------------- |
| 789 | |
| 790 | IMPLICIT NONE |
| 791 | |
| 792 | DOUBLE PRECISION HWHPPB,S,T,U,S2,T2,U2,PI2,ALNTU,ALNST,ALNSU |
| 793 | |
| 794 | PI2=ACOS(-1.D0)**2 |
| 795 | |
| 796 | S2=S**2 |
| 797 | |
| 798 | T2=T**2 |
| 799 | |
| 800 | U2=U**2 |
| 801 | |
| 802 | ALNTU=LOG(T/U) |
| 803 | |
| 804 | ALNST=LOG(-S/T) |
| 805 | |
| 806 | ALNSU=ALNST+ALNTU |
| 807 | |
| 808 | HWHPPB=5.*4. |
| 809 | |
| 810 | & +((2.*S2+2.*(U2-T2)*ALNTU+(T2+U2)*(ALNTU**2+PI2))/S2)**2 |
| 811 | |
| 812 | & +((2.*U2+2.*(T2-S2)*ALNST+(T2+S2)* ALNST**2 )/U2)**2 |
| 813 | |
| 814 | & +((2.*T2+2.*(U2-S2)*ALNSU+(U2+S2)* ALNSU**2 )/T2)**2 |
| 815 | |
| 816 | & +4.*PI2*(((T2-S2+(T2+S2)*ALNST)/U2)**2 |
| 817 | |
| 818 | & +((U2-S2+(U2+S2)*ALNSU)/T2)**2) |
| 819 | |
| 820 | END |
git://git.uio.no / u / mrichter / AliRoot.git / blame