pythiaeRHIC/pythia/pyevwt.f

0001
0002 C*********************************************************************
0003
0004 C...PYEVWT
0005 C...Dummy routine, which the user can replace in order to multiply the
0006 C...standard PYTHIA differential cross-section by a process- and
0007 C...kinematics-dependent factor WTXS. For MSTP(142)=1 this corresponds
0008 C...to generation of weighted events, with weight 1/WTXS, while for
0009 C...MSTP(142)=2 it corresponds to a modification of the underlying
0010 C...physics.
0011
0012       SUBROUTINE PYEVWT(WTXS)
0013
0014 C...Double precision and integer declarations.
0015       IMPLICIT DOUBLE PRECISION(A-H, O-Z)
0016       IMPLICIT INTEGER(I-N)
0017       INTEGER PYK,PYCHGE,PYCOMP
0018 C...Commonblocks.
0019       COMMON/PYDAT1/MSTU(200),PARU(200),MSTJ(200),PARJ(200)
0020       COMMON/PYINT1/MINT(400),VINT(400)
0021       COMMON/PYINT2/ISET(500),KFPR(500,2),COEF(500,20),ICOL(40,4,2)
0022       SAVE /PYDAT1/,/PYINT1/,/PYINT2/
0023
0024 C...Set default weight for WTXS.
0025       WTXS=1D0
0026
0027 C...Read out subprocess number.
0028       ISUB=MINT(1)
0029       ISTSB=ISET(ISUB)
0030
0031 C...Read out tau, y*, cos(theta), tau' (where defined, else =0).
0032       TAU=VINT(21)
0033       YST=VINT(22)
0034       CTH=0D0
0035       IF(ISTSB.EQ.2.OR.ISTSB.EQ.4) CTH=VINT(23)
0036       TAUP=0D0
0037       IF(ISTSB.GE.3.AND.ISTSB.LE.5) TAUP=VINT(26)
0038
0039 C...Read out x_1, x_2, x_F, shat, that, uhat, p_T^2.
0040       X1=VINT(41)
0041       X2=VINT(42)
0042       XF=X1-X2
0043       SHAT=VINT(44)
0044       THAT=VINT(45)
0045       UHAT=VINT(46)
0046       PT2=VINT(48)
0047
0048 C...Modifications by user to be put here.
0049
0050 C...Stop program if this routine is ever called.
0051 C...You should not copy these lines to your own routine.
0052       WRITE(MSTU(11),5000)
0053       CALL PYSTOP(4)
0054
0055 C...Format for error printout.
0056  5000 FORMAT(1X,'Error: you did not link your PYEVWT routine ',
0057      &'correctly.'/1X,'Dummy routine in PYTHIA file called instead.'/
0058      &1X,'Execution stopped!')
0059
0060       RETURN
0061       END