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arorie.f
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1 C*************************************************************
2 
3 
4  SUBROUTINE arorie(S,X1,X3,JL)
5 C
6  common/hiparnt/hipr1(100),ihpr2(50),hint1(100),ihnt2(50)
7  SAVE /hiparnt/
8  common/lujets/n,k(9000,5),p(9000,5),v(9000,5)
9  SAVE /lujets/
10  common/ranseed/nseed
11  SAVE /ranseed/
12 C
13  w=sqrt(s)
14  x2=2.-x1-x3
15  e1=.5*x1*w
16  e3=.5*x3*w
17  p1=sqrt(e1**2-p(jl,5)**2)
18  p3=sqrt(e3**2-p(jl+1,5)**2)
19  cbet=1.
20  IF(p1.GT.0..AND.p3.GT.0.) cbet=(p(jl,5)**2
21  & +p(jl+1,5)**2+2.*e1*e3-s*(1.-x2))/(2.*p1*p3)
22  IF(abs(cbet).GT.1.0) cbet=max(-1.,min(1.,cbet))
23  bet=acos(cbet)
24 
25 C.....MINIMIZE PT1-SQUARED PLUS PT3-SQUARED.....
26  IF(p1.GE.p3) THEN
27  psi=.5*ulangl(p1**2+p3**2*cos(2.*bet),-p3**2*sin(2.*bet))
28  pt1=p1*sin(psi)
29  pz1=p1*cos(psi)
30  pt3=p3*sin(psi+bet)
31  pz3=p3*cos(psi+bet)
32  ELSE IF(p3.GT.p1) THEN
33  psi=.5*ulangl(p3**2+p1**2*cos(2.*bet),-p1**2*sin(2.*bet))
34  pt1=p1*sin(bet+psi)
35  pz1=-p1*cos(bet+psi)
36  pt3=p3*sin(psi)
37  pz3=-p3*cos(psi)
38  ENDIF
39 
40  del=2.0*hipr1(40)*atl_ran(nseed)
41  p(jl,4)=e1
42  p(jl,1)=pt1*sin(del)
43  p(jl,2)=-pt1*cos(del)
44  p(jl,3)=pz1
45  p(jl+2,4)=e3
46  p(jl+2,1)=pt3*sin(del)
47  p(jl+2,2)=-pt3*cos(del)
48  p(jl+2,3)=pz3
49  p(jl+1,4)=w-e1-e3
50  p(jl+1,1)=-p(jl,1)-p(jl+2,1)
51  p(jl+1,2)=-p(jl,2)-p(jl+2,2)
52  p(jl+1,3)=-p(jl,3)-p(jl+2,3)
53  RETURN
54  END