More volume overlaps corrected
[u/mrichter/AliRoot.git] / ISAJET / code / ssgst.F
1 #include "isajet/pilot.h"
2         REAL FUNCTION SSGST(S,AMSQ,Z,I,J)
3 C-----------------------------------------------------------------------
4 C          Function for Sig(qqbar->z_i + z_j
5 C-----------------------------------------------------------------------
6 #if defined(CERNLIB_IMPNONE)
7       IMPLICIT NONE
8 #endif
9 #include "isajet/sssm.inc"
10 #include "isajet/sspar.inc"
11         REAL S,AMSQ,K,Z,MZI,MZJ,RS,TP,BT
12         INTEGER I,J,ITHI,ITHJ
13 C
14         MZI=ABS(AMZISS(I))
15         MZJ=ABS(AMZISS(J))
16         IF (AMZISS(I).LT.0.) THEN
17           ITHI=1
18         ELSE
19           ITHI=0
20         END IF
21         IF (AMZISS(J).LT.0.) THEN
22           ITHJ=1
23         ELSE
24           ITHJ=0
25         END IF
26         RS=SQRT(S)
27         K=SQRT(S*S+(MZI**2-MZJ**2)**2-2*S*(MZI**2+MZJ**2))/
28      $   2./RS
29         TP=S*S-(MZI**2-MZJ**2)**2-4*K*S**1.5*Z+4*K*K*S*Z*Z+
30      $   4*(-1.)**(ITHI+ITHJ+1)*MZI*MZJ*S
31         BT=(S-MZI**2-MZJ**2)/2.-RS*K*Z+AMSQ**2
32         SSGST=TP/BT
33         RETURN
34         END