This routine calculates the polar angles and momenta of two final-state electrons needed to balance the visible energy and momentum. One of the two electrons is assumed to go down the beam axis (PT=0). This routine does not use any ALPHA functions; it simply calculates the result.
It can be found on aloha in ~schmittm/alpha/lib .
SUBROUTINE GGKIN(ECMIN,PIN,PFIN1,PFIN2,THETAF)
C=======================================================================
C
C Test the event under assumption of two-photon kinematics
C
C Given the observed four-vector (PIN), calculate two possible
C directions for one final state electron, assuming the other one
C travels along the beam direction.
C
C input: ECMIN = CM energy
C PIN = four-vector for observed energy
C output: PFIN1(i) = two momentum solutions for electron which is
C assumed to travel along the beam direction
C PFIN2(i) = two momentum solutions for electron which travels
C at some angle (THEATF) to the beam
C THETAF(i)= two angles for second electron
C
C 24-Sep-95 M.Schmitt
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