1 #include "isajet/pilot.h"
4 C Calculate WPAIR decay distribution
5 C D(SIGMA)/D(PT**2)D(Y1)D(Y2)D(OMEGA1)D(OMEGA2)
6 C for modes selected in WPAIR.
8 C Also fix the initial parton types to those selected.
10 C Cross sections from SCHOONSCHIP (1980) neglecting W width
11 C and quark masses. Hence use zero-mass vectors PZERO from
12 C WPAIR to define kinematics.
13 C QK(P1) + QB(P2) --> W1(P3) + W2(P4)
14 C W1(P3) --> QK(Q1) + QB(Q2)
15 C W2(P4) --> QK(Q3) + QB(Q4)
16 C S=(P3+P4)**2, T=(P3-P1)**2, U=(P3-P2)**2
17 C S1=(Q1+P4)**2, T1=(Q1-P1)**2, U1=(Q1-P2)**2
18 C S3=(Q3+P3)**2, T3=(Q3-P2)**2, U3=(Q3-P1)**2
20 C Note that the W+- final couplings have been set equal to 1.
21 C in the SCHOONSCHIP formulas and must be restored.
23 C Need double precision for 32-bit machines.
25 C Ver. 5.35 - correct symmetrization for DN DB -> W+ W-.
26 C Ver. 6.22 - use W + GM decay distributions from
27 C Cortes, Hagiwara, and Herzog, NP B278, 26 (1986)
29 #if defined(CERNLIB_IMPNONE)
32 #include "isajet/itapes.inc"
33 #include "isajet/qcdpar.inc"
34 #include "isajet/jetpar.inc"
35 #include "isajet/primar.inc"
36 #include "isajet/q1q2.inc"
37 #include "isajet/const.inc"
38 #include "isajet/qsave.inc"
39 #include "isajet/wcon.inc"
40 #include "isajet/pjets.inc"
41 #include "isajet/pinits.inc"
42 #include "isajet/wwsig.inc"
43 #include "isajet/wwpar.inc"
45 DIMENSION P1(5),P2(5),QSGN(6),PP1(4),PP2(4)
46 EQUIVALENCE (S,SWW),(T,TWW),(U,UWW)
47 EQUIVALENCE (P1(1),P1WW(1)),(P2(1),P2WW(1))
48 C Double precision kinematics for 32-bit.
49 #if defined(CERNLIB_SINGLE)
50 REAL S,T,U,T1,U1,T3,U3,P1,P2
51 1,TX,UX,TT,UU,TT1,UU1,TT3,UU3,PP1,PP2
52 REAL TERM,WWSS,WWST,WWTT,ZZALL,WZSS,WZST,WZSU,WZTU
55 #if defined(CERNLIB_DOUBLE)
56 DOUBLE PRECISION S,T,U,T1,U1,T3,U3,P1,P2
57 1,TX,UX,TT,UU,TT1,UU1,TT3,UU3,PP1,PP2
58 DOUBLE PRECISION TERM,WWSS,WWST,WWTT,ZZALL,WZSS,WZST,WZSU,WZTU
61 REAL P3IS3,P3IS4,FJAC,AMW1,AMW2,GAM1,GAM2,SGN,QSGN,AMASS3
63 REAL A1,B1,A2,B2,ES,SMS,SMSZG,EQ3(12)
64 REAL Q(5),QB(5),KK(5),E(5),EB(5)
65 INTEGER K,JQ1,JQ3,JW1,JW2,IW1,IW2,IQ1,IQ2,IQ,ISWAPQ,JW,JZ,ISGN
66 INTEGER IFLI,IFLJ,JG,IL,IW
69 DATA QSGN/1.,-1.,-1.,1.,-1.,1./
70 DATA EQ3/2.,-1.,-1.,2.,-1.,2.,0.,-3.,0.,-3.,0.,-3./
76 IF(IDJETS(1).EQ.10.OR.IDJETS(2).EQ.10) GO TO 2
78 IF((IDJETS(1).EQ.80.AND.IDJETS(2).EQ.-80).OR.
79 $(IDJETS(1).EQ.90.AND.IDJETS(2).EQ.90).OR.
80 $(IABS(IDJETS(1)).EQ.80.AND.IDJETS(2).EQ.90)) THEN
111 T1=-2.*(Q1(4)*P1(4)-Q1(1)*P1(1)-Q1(2)*P1(2)-Q1(3)*P1(3))
112 U1=-2.*(Q1(4)*P2(4)-Q1(1)*P2(1)-Q1(2)*P2(2)-Q1(3)*P2(3))
113 T3=-2.*(Q3(4)*P2(4)-Q3(1)*P2(1)-Q3(2)*P2(2)-Q3(3)*P2(3))
114 U3=-2.*(Q3(4)*P1(4)-Q3(1)*P1(1)-Q3(2)*P1(2)-Q3(3)*P1(3))
115 S13=2.*(Q1(4)*Q3(4)-Q1(1)*Q3(1)-Q1(2)*Q3(2)-Q1(3)*Q3(3))
116 C Jacobean for 4-body cross section in terms of squared
117 C matrix exement in narrow resonance approximation--
118 C 1/((P**2-M**2)**2+M**2*GAM**2)=1/(2*M*GAM)*DELTA(P**2-M**2)
120 FJAC=FJAC*ALFA**4/(256.*PI*3.*S**2)
125 FJAC=FJAC/(AMW1*GAM1*AMW2*GAM2)
126 FJAC=FJAC*P(1)*P(2)/SQRT((P(1)**2+AMW1**2)*(P(2)**2+AMW2**2))
128 IF(IABS(IDPAIR(1)).LT.10) FJAC=3.*FJAC
129 IF(IABS(IDPAIR(3)).LT.10) FJAC=3.*FJAC
132 C Standard order is UP + UB --> W+ + W-
134 IF(.NOT.((JETTYP(1).EQ.2.AND.JETTYP(2).EQ.3).OR.(JETTYP(1).EQ.3
135 1.AND.JETTYP(2).EQ.2))) GO TO 200
136 FJAC=.5*FJAC*AQ(2,2)**4
138 C Select W+ W- OR W- W+, swapping T and U for latter.
147 CV=AQDP(IQ,1)/S+EZDP*AQDP(IQ,4)/(S-ZM2)
148 CA=EZDP*BQDP(IQ,4)/(S-ZM2)
151 IF(SGN.LT.0.) ISWAPQ=-1
162 P3(K)=P3IS3*P3WW(K)+P3IS4*P4WW(K)
176 P3(K)=P3IS4*P3WW(K)+P3IS3*P4WW(K)
183 TERM=WWTT(TT,UU,TT1,UU1,TT3,UU3)
184 TERM=TERM-SGN*WWST(TT,UU,TT1,UU1,TT3,UU3,PP1,PP2)
185 TERM=TERM+WWSS(TT,UU,TT1,UU1,TT3,UU3)
186 WWSIG=TERM*QSAVE(2*IQ,1)*QSAVE(2*IQ+1,2)*FJAC
188 TERM=WWTT(UU,TT,UU1,TT1,UU3,TT3)
189 TERM=TERM-SGN*WWST(UU,TT,UU1,TT1,UU3,TT3,PP2,PP1)
190 TERM=TERM+WWSS(UU,TT,UU1,TT1,UU3,TT3)
191 WWSIG=TERM*QSAVE(2*IQ+1,1)*QSAVE(2*IQ,2)*FJAC
197 C Standard order is UP + UB --> Z0 + Z0
199 200 IF(.NOT.(JETTYP(1).EQ.4.AND.JETTYP(2).EQ.4)) GO TO 300
206 CV=AQDP(IQ,4)**2+BQDP(IQ,4)**2
207 CA=2.*AQDP(IQ,4)*BQDP(IQ,4)
208 CV1=AQDP(JQWW(1),4)**2+BQDP(JQWW(1),4)**2
209 CA1=2.*AQDP(JQWW(1),4)*BQDP(JQWW(1),4)
210 CV3=AQDP(JQWW(2),4)**2+BQDP(JQWW(2),4)**2
211 CA3=2.*AQDP(JQWW(2),4)*BQDP(JQWW(2),4)
213 TERM=ZZALL(TX,UX,T1,U1,T3,U3,P1,P2)
214 IF(INITYP(1).EQ.2*IQ) THEN
215 WWSIG=TERM*QSAVE(2*IQ,1)*QSAVE(2*IQ+1,2)*FJAC
217 WWSIG=TERM*QSAVE(2*IQ+1,1)*QSAVE(2*IQ,2)*FJAC
223 C Standard order is DN + UB --> W- + Z0
227 ISGN=-ISIGN(1,IDJETS(JW))
229 CV3=AQDP(JQWW(JZ),4)**2+BQDP(JQWW(JZ),4)**2
230 CA3=2.*AQDP(JQWW(JZ),4)*BQDP(JQWW(JZ),4)
231 FJAC=.5*FJAC*AQ(1,2)**2
233 C Select quarks. Formulas are for DN UB --> W- Z0.
234 C Use symmetry for other cases.
238 C Find whether IQ1 should be fermion or antifermion.
239 IF(IQ1.EQ.2*(IQ1/2)) THEN
249 CS=AQDP(IQ,JETTYP(JW))*EZDP/(S-WM2)
250 CT=AQDP(IQ,JETTYP(JW))*(AQDP(IFLJ,4)+BQDP(IFLJ,4))
251 CU=AQDP(IQ,JETTYP(JW))*(AQDP(IFLI,4)+BQDP(IFLI,4))
253 C SWAP T AND U AS NEEDED
254 IF(ISWAPQ*ISGN.GT.0) THEN
278 TERM=WZSS(TT,UU,TT1,UU1,TT3,UU3,PP1,PP2)
279 TERM=TERM-SGN*WZST(TT,UU,TT1,UU1,TT3,UU3,PP1,PP2)
280 TERM=TERM-SGN*WZSU(TT,UU,TT1,UU1,TT3,UU3,PP1,PP2)
281 TERM=TERM+WZTU(TT,UU,TT1,UU1,TT3,UU3,PP1,PP2)
282 WWSIG=TERM*QSAVE(IQ1,1)*QSAVE(IQ2,2)*FJAC
286 C Do Z+gamma or W+gamma 3-body subprocesses
291 C Standard order is UP + UB --> Z0 + gamma
293 IF(.NOT.(JETTYP(1).EQ.4.AND.JETTYP(2).EQ.1)) GO TO 505
294 FJAC=S/SCM*P(1)/SQRT(P(1)**2+WMASS(4)**2)*UNITS
308 E(K)=SNGL(PZERO(K,1))
309 EB(K)=SNGL(PZERO(K,2))
312 IF(INITYP(1).EQ.2*IQ) THEN
313 SMS=SMSZG(Q,QB,KK,E,EB,A1,B1,A2,B2)
314 TERM=ES**3*(EQ3(IQ)/3.)**2*SMS/192./PI**4/WMASS(4)/WGAM(4)/S**2
315 WWSIG=TERM*QSAVE(2*IQ,1)*QSAVE(2*IQ+1,2)*FJAC/2.
317 SMS=SMSZG(QB,Q,KK,E,EB,A1,B1,A2,B2)
318 TERM=ES**3*(EQ3(IQ)/3.)**2*SMS/192./PI**4/WMASS(4)/WGAM(4)/S**2
319 WWSIG=TERM*QSAVE(2*IQ+1,1)*QSAVE(2*IQ,2)*FJAC/2.
321 505 IF(.NOT.(JETTYP(1).EQ.1.AND.JETTYP(2).EQ.4)) GO TO 509
322 FJAC=S/SCM*P(2)/SQRT(P(2)**2+WMASS(4)**2)*UNITS
336 E(K)=SNGL(PZERO(K,1))
337 EB(K)=SNGL(PZERO(K,2))
340 IF(INITYP(1).EQ.2*IQ) THEN
341 SMS=SMSZG(Q,QB,KK,E,EB,A1,B1,A2,B2)
342 TERM=ES**3*(EQ3(IQ)/3.)**2*SMS/192./PI**4/WMASS(4)/WGAM(4)/S**2
343 WWSIG=TERM*QSAVE(2*IQ,1)*QSAVE(2*IQ+1,2)*FJAC/2.
345 SMS=SMSZG(QB,Q,KK,E,EB,A1,B1,A2,B2)
346 TERM=ES**3*(EQ3(IQ)/3.)**2*SMS/192./PI**4/WMASS(4)/WGAM(4)/S**2
347 WWSIG=TERM*QSAVE(2*IQ+1,1)*QSAVE(2*IQ,2)*FJAC/2.
351 C Standard order is DN + UB --> W- + GM
354 509 IF (ABS(IDJETS(1)).EQ.80.OR.ABS(IDJETS(2)).EQ.80) THEN
355 IF(IDJETS(2).EQ.10) THEN
376 IF(IDJETS(JW).EQ.80) THEN
382 T1=-2.*(Q1(4)*P1(4)-Q1(1)*P1(1)-Q1(2)*P1(2)-Q1(3)*P1(3))
383 U1=-2.*(Q1(4)*P2(4)-Q1(1)*P2(1)-Q1(2)*P2(2)-Q1(3)*P2(3))
386 FJAC=FJAC*P(JW)/SQRT(P(JW)**2+WM2)
387 C Sum over quarks. Formulas are for DN UB --> W- GM.
388 C Use symmetry for other cases.
397 C Swap t and u as necessary
398 IF((LQK1.AND.IW.EQ.3).OR.(.NOT.LQK1.AND.IW.EQ.2)) THEN
409 C Lepton or quark pointer
413 C Matrix element - properly crossed variables.
414 C Remember PZERO(K,1) is always the fermion.
416 P1DQ2=P1(4)*PZERO(4,2)-P1(1)*PZERO(1,2)-P1(2)*PZERO(2,2)
418 P2DQ1=P2(4)*PZERO(4,1)-P2(1)*PZERO(1,1)-P2(2)*PZERO(2,1)
421 P1DQ2=P2(4)*PZERO(4,2)-P2(1)*PZERO(1,2)-P2(2)*PZERO(2,2)
423 P2DQ1=P1(4)*PZERO(4,1)-P1(1)*PZERO(1,1)-P1(2)*PZERO(2,1)
426 TERM=ALFA**2/(8.*SIN2W*S**2)*TBRWW(IW,JW)*RBRWW(IL,IW,JW)
427 $*(-1./3.+UU/(TT+UU))**2/(TT*UU)*(4.*P2DQ1**2+4.*P1DQ2**2)
428 WWSIG=TERM*QSAVE(IQ1,1)*QSAVE(IQ2,2)*FJAC