1 #include "isajet/pilot.h"
4 C Compute D(SIGMA)/D(PT**2)D(Y1)D(Y2) for gamma + jet and
7 C SIGMA = cross section summed over quark types allowed by
9 C SIGS(I) = partial cross section for I1 + I2 --> I3 + I4.
10 C INOUT(I) = IOPAK**3*I4 + IOPAK**2*I3 + IOPAK*I2 + I1
13 C Cross sections from Berger, Bratten, and Field, Nucl. Phys.
14 C B239, 52 (1984), Table 2. Masses are neglected.
17 #if defined(CERNLIB_IMPNONE)
20 #include "isajet/itapes.inc"
21 #include "isajet/qcdpar.inc"
22 #include "isajet/jetpar.inc"
23 #include "isajet/primar.inc"
24 #include "isajet/q1q2.inc"
25 #include "isajet/jetsig.inc"
26 #include "isajet/const.inc"
27 #include "isajet/wcon.inc"
29 REAL BBF1,BBF2,BBF3,S,T,U,FJAC,STRUC,SIG0,SIG,BBF3TU,BBF3UT
33 EQUIVALENCE (X(1),X1),(S,SHAT),(T,THAT),(U,UHAT)
34 DATA LISTJ/9,1,-1,2,-2,3,-3,4,-4,5,-5,6,-6/
36 C Cross sections with couplings and Jacobean removed.
37 BBF1(S,T,U)=8./9.*(U/T+T/U)
38 BBF2(S,T,U)=2./3.*(U/T+T/U)
39 BBF3(S,T,U)=-1./3.*(U/S+S/U)
41 C Initialize cross sections.
49 C Kinematics and structure functions for CH and lighter quarks
51 CALL TWOKIN(0.,0.,0.,0.)
52 FJAC=SHAT/SCM*UNITS*PI/SHAT**2
53 IF(X1.GE.1.0.OR.X2.GE.1.0) RETURN
56 QSAVE(IQ,IH)=STRUC(X(IH),QSQ,IQ,IDIN(IH))/X(IH)
59 C Compute cross sections summed over all types allowed by
62 IF(.NOT.(GOQ(26,1).OR.GOQ(26,2))) RETURN
66 IF((GOQ(1,1).AND.GOQ(26,2)).OR.(GOQ(26,1).AND.GOQ(1,2))) THEN
67 SIG0=.5*FJAC*ALFQSQ*ALFA*BBF1(S,T,U)
70 SIG=SIG0*AQ(IFL,1)**2*QSAVE(2*I,1)*QSAVE(2*I+1,2)
71 IF(GOQ(26,1).AND.GOQ(1,2)) CALL SIGFIL(SIG,2*I,2*I+1,26,1)
72 IF(GOQ(1,1).AND.GOQ(26,2)) CALL SIGFIL(SIG,2*I,2*I+1,1,26)
73 SIG=SIG0*AQ(IFL,1)**2*QSAVE(2*I+1,1)*QSAVE(2*I,2)
74 IF(GOQ(26,1).AND.GOQ(1,2)) CALL SIGFIL(SIG,2*I+1,2*I,26,1)
75 IF(GOQ(1,1).AND.GOQ(26,2)) CALL SIGFIL(SIG,2*I+1,2*I,1,26)
81 IF(GOQ(26,1).AND.GOQ(26,2)) THEN
82 SIG0=.5*FJAC*ALFA**2*BBF2(S,T,U)
85 SIG=SIG0*AQ(IFL,1)**4*QSAVE(2*I,1)*QSAVE(2*I+1,2)
86 CALL SIGFIL(SIG,2*I,2*I+1,26,26)
87 SIG=SIG0*AQ(IFL,1)**4*QSAVE(2*I+1,1)*QSAVE(2*I,2)
88 CALL SIGFIL(SIG,2*I+1,2*I,26,26)
94 BBF3TU=.5*FJAC*ALFA*ALFQSQ*BBF3(S,T,U)
95 BBF3UT=.5*FJAC*ALFA*ALFQSQ*BBF3(S,U,T)
98 IF(GOQ(26,1).AND.GOQ(I,2)) THEN
99 SIG=BBF3TU*AQ(IFL,1)**2*QSAVE(I,1)*QSAVE(1,2)
100 CALL SIGFIL(SIG,I,1,26,I)
101 SIG=BBF3UT*AQ(IFL,1)**2*QSAVE(1,1)*QSAVE(I,2)
102 CALL SIGFIL(SIG,1,I,26,I)
104 IF(GOQ(I,1).AND.GOQ(26,2)) THEN
105 SIG=BBF3UT*AQ(IFL,1)**2*QSAVE(I,1)*QSAVE(1,2)
106 CALL SIGFIL(SIG,I,1,I,26)
107 SIG=BBF3TU*AQ(IFL,1)**2*QSAVE(1,1)*QSAVE(I,2)
108 CALL SIGFIL(SIG,1,I,I,26)