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Added the magnetic field as a static member of the AliL3Transform class,
[u/mrichter/AliRoot.git] / ISAJET / code / sigqcd.F
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0795afa3 1#include "isajet/pilot.h"
2 SUBROUTINE SIGQCD
3C
4C Compute D(SIGMA)/D(PT**2)D(Y1)D(Y2)
5C Include quark masses for ch, bt, and tp and 4th generation.
6C Note ch is now treated as heavy.
7C
8C SIGMA = cross section summed over quark types allowed by
9C JETTYPE card.
10C SIGS(I) = partial cross section for I1 + I2 --> I3 + I4.
11C INOUT(I) = IOPAK**3*I4 + IOPAK**2*I3 + IOPAK*I2 + I1
12C using JETTYPE code.
13C
14C Cross sections from Feynman, Field and Fox, P.R. D18, 3320
15C Massive cross sections from B. Combridge, N.P. B151, 429.
16C Extra factor of 1/2 needed for non-identical jets since all
17C all jets are treated as identical.
18C
19C Ver 6.35: Fix kinematics for gl + tp -> gl + tp, etc.
20C
21#if defined(CERNLIB_IMPNONE)
22 IMPLICIT NONE
23#endif
24#include "isajet/itapes.inc"
25#include "isajet/qcdpar.inc"
26#include "isajet/jetpar.inc"
27#include "isajet/primar.inc"
28#include "isajet/q1q2.inc"
29#include "isajet/jetsig.inc"
30#include "isajet/const.inc"
31C
32 REAL X(2),QSAVE(13,2),EBT(2)
33 EQUIVALENCE (X(1),X1),(S,SHAT),(T,THAT),(U,UHAT)
34 REAL FFF1,FFF2,FFF3,FFF4,FFF5,FFF6,FFF7,S,T,U,FGQ,AM2,FQQ,
35 $ QFCN,STRUC,FJAC,SIG,AMASS,SIG1,AMQ,FJACBT,SIG2,QQ,XQMIN,
36 $ E1,E2
37 INTEGER IQ,IH,I,J,IFL,JTYP1,JTYP2,IQ1,IQ2
38C
39C Elementary cross sections from Feynman, Field, and Fox.
40C
41 FFF1(S,T,U)=4./9.*(S**2+U**2)/T**2
42 FFF2(S,T,U)=4./9.*((S**2+U**2)/T**2+(S**2+T**2)/U**2)
43 1-8./27.*S**2/(U*T)
44 FFF3(S,T,U)=4./9.*((S**2+U**2)/T**2+(T**2+U**2)/S**2)
45 1-8./27.*U**2/(S*T)
46 FFF4(S,T,U)=32./27.*(U**2+T**2)/(U*T)-8./3.*(U**2+T**2)/S**2
47 FFF5(S,T,U)=1./6.*(U**2+T**2)/(U*T)-3./8.*(U**2+T**2)/S**2
48 FFF6(S,T,U)=-4./9.*(U**2+S**2)/(U*S)+(U**2+S**2)/T**2
49 FFF7(S,T,U)=9./2.*(3.-U*T/S**2-U*S/T**2-S*T/U**2)
50C Heavy quark cross sections from Combridge
51 FGQ(S,T,U)=2.*(S-AM2)*(AM2-U)/T**2
52 1+4./9.*((S-AM2)*(AM2-U)+2.*AM2*(S+AM2))/(S-AM2)**2
53 2+4./9.*((S-AM2)*(AM2-U)+2.*AM2*(AM2+U))/(AM2-U)**2
54 3+1./9.*AM2*(4.*AM2-T)/((S-AM2)*(AM2-U))
55 4+((S-AM2)*(AM2-U)+AM2*(S-U))/(T*(S-AM2))
56 5-((S-AM2)*(AM2-U)-AM2*(S-U))/(T*(AM2-U))
57 FQQ(S,T,U)=4./9.*((AM2-U)**2+(S-AM2)**2+2.*AM2*T)/T**2
58 QFCN(IQ,IH)=STRUC(X(IH),QSQ,IQ,IDIN(IH))/X(IH)
59C
60C Use massless kinematics for ch and lighter quarks.
61C
62 CALL TWOKIN(0.,0.,0.,0.)
63 FJAC=SHAT/SCM*UNITS
64 FJAC=FJAC*PI*ALFQSQ**2/SHAT**2
65C
66C Initialize cross sections.
67C
68 SIGMA=0.
69 NSIGS=0
70 DO 100 I=1,MXSIGS
71 SIGS(I)=0.
72100 CONTINUE
73 IF(X1.GE.1.0.OR.X2.GE.1.0) RETURN
74C Compute structure functions
75 DO 110 IH=1,2
76 DO 110 IQ=1,7
77 QSAVE(IQ,IH)=STRUC(X(IH),QSQ,IQ,IDIN(IH))/X(IH)
78110 CONTINUE
79C
80C Compute cross sections summed over quark types allowed by
81C JETTYPE card.
82C
83C Gluon-gluon
84 IF(.NOT.(GOQ(1,1).AND.GOQ(1,2))) GO TO 210
85 SIG=.5*FJAC*QSAVE(1,1)*QSAVE(1,2)*FFF7(S,T,U)
86 CALL SIGFIL(SIG,1,1,1,1)
87C
88 DO 201 I=1,3
89 SIG=.5*FJAC*QSAVE(2*I,1)*QSAVE(2*I+1,2)*FFF4(S,T,U)
90 CALL SIGFIL(SIG,2*I,2*I+1,1,1)
91 SIG=.5*FJAC*QSAVE(2*I+1,1)*QSAVE(2*I,2)*FFF4(S,U,T)
92 CALL SIGFIL(SIG,2*I+1,2*I,1,1)
93201 CONTINUE
94C
95C Quark-gluon
96210 CONTINUE
97 DO 211 I=2,7
98 IF(.NOT.(GOQ(I,1).AND.GOQ(1,2))) GO TO 212
99 SIG=.5*FJAC*QSAVE(I,1)*QSAVE(1,2)*FFF6(S,T,U)
100 CALL SIGFIL(SIG,I,1,I,1)
101 SIG=.5*FJAC*QSAVE(1,1)*QSAVE(I,2)*FFF6(S,U,T)
102 CALL SIGFIL(SIG,1,I,I,1)
103212 CONTINUE
104 IF(.NOT.(GOQ(1,1).AND.GOQ(I,2))) GO TO 211
105 SIG=.5*FJAC*QSAVE(1,1)*QSAVE(I,2)*FFF6(S,T,U)
106 CALL SIGFIL(SIG,1,I,1,I)
107 SIG=.5*FJAC*QSAVE(I,1)*QSAVE(1,2)*FFF6(S,U,T)
108 CALL SIGFIL(SIG,I,1,1,I)
109211 CONTINUE
110C
111C Identical quark-quark
112 DO 220 I=2,7
113 IF(.NOT.(GOQ(I,1).AND.GOQ(I,2))) GO TO 220
114 SIG=.5*FJAC*QSAVE(I,1)*QSAVE(I,2)*FFF2(S,T,U)
115 CALL SIGFIL(SIG,I,I,I,I)
116220 CONTINUE
117C
118C Identical quark-antiquark
119 DO 230 I=1,3
120 IF(SHAT.LT.4.*AMASS(I)**2) GO TO 230
121 IF(.NOT.(GOQ(2*I,1).AND.GOQ(2*I+1,2))) GO TO 235
122 SIG=.5*FJAC*QSAVE(1,1)*QSAVE(1,2)*FFF5(S,T,U)
123 CALL SIGFIL(SIG,1,1,2*I,2*I+1)
124 DO 231 J=1,3
125 IF(J.EQ.I) GO TO 231
126 SIG=.5*FJAC*QSAVE(2*J,1)*QSAVE(2*J+1,2)*FFF1(T,S,U)
127 CALL SIGFIL(SIG,2*J,2*J+1,2*I,2*I+1)
128 SIG=.5*FJAC*QSAVE(2*J+1,1)*QSAVE(2*J,2)*FFF1(T,S,U)
129 CALL SIGFIL(SIG,2*J+1,2*J,2*I,2*I+1)
130231 CONTINUE
131 SIG=.5*FJAC*QSAVE(2*I,1)*QSAVE(2*I+1,2)*FFF3(S,T,U)
132 CALL SIGFIL(SIG,2*I,2*I+1,2*I,2*I+1)
133 SIG=.5*FJAC*QSAVE(2*I+1,1)*QSAVE(2*I,2)*FFF3(S,U,T)
134 CALL SIGFIL(SIG,2*I+1,2*I,2*I,2*I+1)
135C
136235 CONTINUE
137 IF(.NOT.(GOQ(2*I+1,1).AND.GOQ(2*I,2))) GO TO 230
138 SIG=.5*FJAC*QSAVE(1,1)*QSAVE(1,2)*FFF5(S,T,U)
139 CALL SIGFIL(SIG,1,1,2*I+1,2*I)
140 DO 236 J=1,3
141 IF(J.EQ.I) GO TO 236
142 SIG=.5*FJAC*QSAVE(2*J,1)*QSAVE(2*J+1,2)*FFF1(T,S,U)
143 CALL SIGFIL(SIG,2*J,2*J+1,2*I+1,2*I)
144 SIG=.5*FJAC*QSAVE(2*J+1,1)*QSAVE(2*J,2)*FFF1(T,S,U)
145 CALL SIGFIL(SIG,2*J+1,2*J,2*I+1,2*I)
146236 CONTINUE
147 SIG1=.5*FJAC*QSAVE(2*I,1)*QSAVE(2*I+1,2)*FFF3(S,U,T)
148 CALL SIGFIL(SIG1,2*I,2*I+1,2*I+1,2*I)
149 SIG=.5*FJAC*QSAVE(2*I+1,1)*QSAVE(2*I,2)*FFF3(S,T,U)
150 CALL SIGFIL(SIG,2*I+1,2*I,2*I+1,2*I)
151230 CONTINUE
152C
153C General massless quark-quark
154 DO 240 I=2,7
155 DO 241 J=2,7
156 IF(.NOT.(GOQ(I,1).AND.GOQ(J,2))) GO TO 241
157 IF((I/2).EQ.(J/2)) GO TO 241
158 SIG=.5*FJAC*QSAVE(I,1)*QSAVE(J,2)*FFF1(S,T,U)
159 CALL SIGFIL(SIG,I,J,I,J)
160 SIG=.5*FJAC*QSAVE(J,1)*QSAVE(I,2)*FFF1(S,U,T)
161 CALL SIGFIL(SIG,I,J,J,I)
162241 CONTINUE
163240 CONTINUE
164C
165C CH+CB, BT+BB, and TP+TB cross sections.
166C Y=-log(tan(theta/2)), so Jacobean contains P1*P2/E1*E2.
167C Also fourth generation.
168C
169 DO 250 IQ=1,5
170 IFL=IQ+3
171 JTYP1=2*IFL
172 JTYP2=JTYP1+1
173 IF(.NOT.((GOQ(JTYP1,1).AND.GOQ(JTYP2,2)).OR.
174 1 (GOQ(JTYP2,1).AND.GOQ(JTYP1,2)))) GO TO 250
175 AMQ=AMASS(IFL)
176 IF(AMQ.LT.0.) GO TO 250
177 AM2=AMQ**2
178 CALL TWOKIN(0.,0.,AMQ,AMQ)
179 IF(X(1).GE.1..OR.X(2).GE.1.) GO TO 250
180 EBT(1)=SQRT(P(1)**2+AM2)
181 EBT(2)=SQRT(P(2)**2+AM2)
182 FJACBT=.5*S/SCM*UNITS*P(1)*P(2)/(EBT(1)*EBT(2))
183 SIG1=12.*(AM2-T)*(AM2-U)/S**2
184 1 +8./3.*((AM2-T)*(AM2-U)-2.*AM2*(AM2+T))/(AM2-T)**2
185 2 +8./3.*((AM2-T)*(AM2-U)-2.*AM2*(AM2+U))/(AM2-U)**2
186 3 -2./3.*AM2*(S-4.*AM2)/((AM2-T)*(AM2-U))
187 4 -6.*((AM2-T)*(AM2-U)+AM2*(U-T))/(S*(AM2-T))
188 5 -6.*((AM2-T)*(AM2-U)+AM2*(T-U))/(S*(AM2-U))
189 SIG1=SIG1*PI**2*ALFQSQ**2/(16.*PI*S**2)
190 SIG=FJACBT*SIG1*STRUC(X(1),QSQ,1,IDIN(1))/X(1)
191 1 *STRUC(X(2),QSQ,1,IDIN(2))/X(2)
192 IF(GOQ(JTYP1,1).AND.GOQ(JTYP2,2))
193 $ CALL SIGFIL(SIG,1,1,JTYP1,JTYP2)
194 IF(GOQ(JTYP2,1).AND.GOQ(JTYP1,2))
195 $ CALL SIGFIL(SIG,1,1,JTYP2,JTYP1)
196C
197 SIG2=((AM2-T)**2+(AM2-U)**2+2.*S*AM2)/S**2
198 SIG2=FJACBT*SIG2*64.*PI**2*ALFQSQ**2/(9.*16.*PI*S**2)
199 DO 255 I=1,3
200 QQ=STRUC(X(1),QSQ,2*I,IDIN(1))*STRUC(X(2),QSQ,2*I+1,IDIN(2))
201 SIG=SIG2*QQ/(X(1)*X(2))
202 IF(GOQ(JTYP1,1).AND.GOQ(JTYP2,2))
203 $ CALL SIGFIL(SIG,2*I,2*I+1,JTYP1,JTYP2)
204 IF(GOQ(JTYP2,1).AND.GOQ(JTYP1,2))
205 $ CALL SIGFIL(SIG,2*I,2*I+1,JTYP2,JTYP1)
206 QQ=STRUC(X(1),QSQ,2*I+1,IDIN(1))*STRUC(X(2),QSQ,2*I,IDIN(2))
207 SIG=SIG2*QQ/(X(1)*X(2))
208 IF(GOQ(JTYP1,1).AND.GOQ(JTYP2,2))
209 $ CALL SIGFIL(SIG,2*I+1,2*I,JTYP1,JTYP2)
210 IF(GOQ(JTYP2,1).AND.GOQ(JTYP1,2))
211 $ CALL SIGFIL(SIG,2*I+1,2*I,JTYP2,JTYP1)
212255 CONTINUE
213250 CONTINUE
214C
215C Gluon + heavy quark
216 DO 300 IQ=8,13.
217 IF(.NOT.(GOQ(1,1).AND.GOQ(IQ,2))) GO TO 310
218 AMQ=AMASS(IQ/2)
219 AM2=AMQ**2
220 XQMIN=AMQ/ECM
221 E1=P(1)
222 E2=SQRT(P(2)**2+AM2)
223 FJAC=.5*S/SCM*UNITS*PI*ALFQSQ**2/S**2
224 CALL TWOKIN(0.,AMQ,0.,AMQ)
225 IF(X(1).LT.1..AND.X(2).LT.1..AND.X(2).GT.XQMIN) THEN
226 SIG=FJAC*P(1)*P(2)/(E1*E2)*FGQ(S,T,U)*QFCN(1,1)*QFCN(IQ,2)
227 CALL SIGFIL(SIG,1,IQ,1,IQ)
228 ENDIF
229 CALL TWOKIN(AMQ,0.,0.,AMQ)
230 IF(X(1).LT.1..AND.X(2).LT.1..AND.X(1).GT.XQMIN) THEN
231 SIG=FJAC*P(1)*P(2)/(E1*E2)*FGQ(S,U,T)*QFCN(IQ,1)*QFCN(1,2)
232 CALL SIGFIL(SIG,IQ,1,1,IQ)
233 ENDIF
234C
235310 IF(.NOT.(GOQ(IQ,1).AND.GOQ(1,2))) GO TO 300
236 AMQ=AMASS(IQ/2)
237 AM2=AMQ**2
238 XQMIN=AMQ/ECM
239 E1=SQRT(P(1)**2+AM2)
240 E2=P(2)
241 FJAC=.5*S/SCM*UNITS*PI*ALFQSQ**2/S**2
242 CALL TWOKIN(0.,AMQ,AMQ,0.)
243 IF(X(1).LT.1..AND.X(2).LT.1..AND.X(2).GT.XQMIN) THEN
244 SIG=FJAC*P(1)*P(2)/(E1*E2)*FGQ(S,U,T)*QFCN(1,1)*QFCN(IQ,2)
245 CALL SIGFIL(SIG,1,IQ,IQ,1)
246 ENDIF
247 CALL TWOKIN(AMQ,0.,AMQ,0.)
248 IF(X(1).LT.1..AND.X(2).LT.1..AND.X(1).GT.XQMIN) THEN
249 SIG=FJAC*P(1)*P(2)/(E1*E2)*FGQ(S,T,U)*QFCN(IQ,1)*QFCN(1,2)
250 CALL SIGFIL(SIG,IQ,1,IQ,1)
251 ENDIF
252300 CONTINUE
253C
254C Light quark + heavy quark
255 DO 320 IQ1=2,7
256 DO 330 IQ2=8,13
257 IF(.NOT.(GOQ(IQ1,1).AND.GOQ(IQ2,2))) GO TO 340
258 AMQ=AMASS(IQ2/2)
259 AM2=AMQ**2
260 XQMIN=AMQ/ECM
261 E1=P(1)
262 E2=SQRT(P(2)**2+AM2)
263 FJAC=.5*S/SCM*UNITS*PI*ALFQSQ**2/S**2
264 CALL TWOKIN(0.,AMQ,0.,AMQ)
265 IF(X(1).LT.1..AND.X(2).LT.1..AND.X(2).GT.XQMIN) THEN
266 SIG=FJAC*P(1)*P(2)/(E1*E2)*FQQ(S,T,U)*QFCN(IQ1,1)
267 $ *QFCN(IQ2,2)
268 CALL SIGFIL(SIG,IQ1,IQ2,IQ1,IQ2)
269 ENDIF
270 CALL TWOKIN(AMQ,0.,0.,AMQ)
271 IF(X(1).LT.1..AND.X(2).LT.1..AND.X(1).GT.XQMIN) THEN
272 SIG=FJAC*P(1)*P(2)/(E1*E2)*FQQ(S,U,T)*QFCN(IQ1,2)
273 $ *QFCN(IQ2,1)
274 CALL SIGFIL(SIG,IQ2,IQ1,IQ1,IQ2)
275 ENDIF
276C
277340 IF(.NOT.(GOQ(IQ1,2).AND.GOQ(IQ2,1))) GO TO 330
278 AMQ=AMASS(IQ2/2)
279 AM2=AMQ**2
280 XQMIN=AMQ/ECM
281 E1=SQRT(P(1)**2+AM2)
282 E2=P(2)
283 FJAC=.5*S/SCM*UNITS*PI*ALFQSQ**2/S**2
284 CALL TWOKIN(0.,AMQ,AMQ,0.)
285 IF(X(1).LT.1..AND.X(2).LT.1..AND.X(2).GT.XQMIN) THEN
286 SIG=FJAC*P(1)*P(2)/(E1*E2)*FQQ(S,U,T)*QFCN(IQ1,1)
287 $ *QFCN(IQ2,2)
288 CALL SIGFIL(SIG,IQ1,IQ2,IQ2,IQ1)
289 ENDIF
290 CALL TWOKIN(AMQ,0.,AMQ,0.)
291 IF(X(1).LT.1..AND.X(2).LT.1..AND.X(1).GT.XQMIN) THEN
292 SIG=FJAC*P(1)*P(2)/(E1*E2)*FQQ(S,T,U)*QFCN(IQ1,2)
293 $ *QFCN(IQ2,1)
294 CALL SIGFIL(SIG,IQ2,IQ1,IQ2,IQ1)
295 ENDIF
296330 CONTINUE
297320 CONTINUE
298C
299 RETURN
300 END