pythiaeRHIC/pythia/pyrvg3.f

0001
0002 C*********************************************************************
0003
0004 C...PYRVG3
0005 C...Function to do Y integration over true interference contributions
0006
0007       FUNCTION PYRVG3(X)
0008
0009       IMPLICIT NONE
0010       COMMON/PYRVPM/RM(0:3),A(2),B(2),RESM(2),RESW(2),MFLAG
0011 C...Second Dalitz variable for PYRVG4
0012       COMMON/PYG2DX/X1
0013       DOUBLE PRECISION RM, A, B, RESM, RESW, X, X1
0014       DOUBLE PRECISION E2, E3, C1, SQ1, SR1, SR2, YMIN, YMAX
0015       DOUBLE PRECISION PYRVG3, PYRVG4, PYGAU2
0016       LOGICAL MFLAG
0017       EXTERNAL PYGAU2,PYRVG4
0018       SAVE/PYRVPM/,/PYG2DX/
0019       PYRVG3=0D0
0020       C1=2D0*SQRT(MAX(1D-9,X))
0021       X1=X
0022       IF (.NOT.MFLAG) THEN
0023         E2    = X/C1
0024         E3    = (RM(0)**2-X)/C1
0025         YMIN  = 0D0
0026         YMAX  = 4D0*E2*E3
0027       ELSE
0028         E2    = (X-RM(1)**2+RM(2)**2)/C1
0029         E3    = (RM(0)**2-X-RM(3)**2)/C1
0030         SQ1   = (E2+E3)**2
0031         SR1   = SQRT(MAX(0D0,E2**2-RM(2)**2))
0032         SR2   = SQRT(MAX(0D0,E3**2-RM(3)**2))
0033         YMIN  = SQ1-(SR1+SR2)**2
0034         YMAX  = SQ1-(SR1-SR2)**2
0035       ENDIF
0036       PYRVG3 = PYGAU2(PYRVG4,YMIN,YMAX,1D-3)
0037       RETURN
0038       END