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Viewing changes to tests/input_files/IOTestsComparison/IOExportV4IOTest/export_matrix_element_v4_standalone/matrix.f

  • Committer: olivier Mattelaer
  • Date: 2016-05-12 11:00:18 UTC
  • mfrom: (262.1.150 2.3.4)
  • Revision ID: olivier.mattelaer@uclouvain.be-20160512110018-sevb79f0wm4g8mpp
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tests/input_files/IOTestsComparison/IOExportV4IOTest/export_matrix_element_v4_standalone/matrix.f
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      DO IHEL=1,NEXTERNAL
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        JC(IHEL) = +1
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      ENDDO
 
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C     When spin-2 particles are involved, the Helicity filtering is
 
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C      dangerous for the 2->1 topology.
 
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C     This is because depending on the MC setup the initial PS points
 
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C      have back-to-back initial states
 
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C     for which some of the spin-2 helicity configurations are zero.
 
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C      But they are no longer zero
 
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C     if the point is boosted on the z-axis. Remember that HELAS
 
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C      helicity amplitudes are no longer
 
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C     lorentz invariant with expternal spin-2 particles (only the
 
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C      helicity sum is).
 
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C     For this reason, we simply remove the filterin when there is
 
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C      only three external particles.
 
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      IF (NEXTERNAL.LE.3) THEN
 
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        DO IHEL=1,NCOMB
 
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          GOODHEL(IHEL)=.TRUE.
 
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        ENDDO
 
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      ENDIF
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      ANS = 0D0
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      DO IHEL=1,NCOMB
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        IF (USERHEL.EQ.-1.OR.USERHEL.EQ.IHEL) THEN
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      RETURN
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      END
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