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38 lines
1.4 KiB
38 lines
1.4 KiB
!
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! SPDX-License-Identifier: GPL-3.0-or-later
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! Copyright (C) 2019-2022, respective authors of MCFM.
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!
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function M1bit1(j1,j2,j3,j4,j5,j6,za,zb)
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c Z. Bern, L. Dixon, D.A. Kosower, e-Print:hep-ph/9708239
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c Eq 7.1
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implicit none
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include 'types.f'
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include 'mxpart.f'
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include 'zprods_decl.f'
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include 'sprods_com.f'
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integer:: j1,j2,j3,j4,j5,j6
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real(dp):: t,delta12,delta56,Delta3
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complex(dp):: zab2,zba2,zab,M1bit1
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c Statement functions
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zab2(j1,j2,j3,j4)=za(j1,j2)*zb(j2,j4)+za(j1,j3)*zb(j3,j4)
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zba2(j1,j2,j3,j4)=zb(j1,j2)*za(j2,j4)+zb(j1,j3)*za(j3,j4)
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zab(j1,j2,j3)=za(j1,j2)*zb(j2,j3)
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c End statement functions
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delta12=s(j1,j2)-s(j3,j4)-s(j5,j6)
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delta56=s(j5,j6)-s(j1,j2)-s(j3,j4)
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Delta3=s(j1,j2)**2+s(j3,j4)**2+s(j5,j6)**2
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& -2*s(j1,j2)*s(j3,j4)-2*s(j3,j4)*s(j5,j6)-2*s(j5,j6)*s(j1,j2)
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M1bit1=
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& +2/(zab2(j1,j3,j4,j2)*zab2(j3,j1,j2,j4)*Delta3)
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& *(zb(j1,j3)/za(j5,j6)
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& *(za(j2,j1)*zba2(j1,j3,j4,j5)
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& -(zab2(j2,j3,j4,j1)*za(j1,j5)+zab2(j2,j3,j4,j2)*za(j2,j5)))
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& *(za(j1,j5)*t(j1,j2,j4)+zab(j1,j2,j6)*za(j6,j5))
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& -zb(j1,j6)*za(j2,j4)/(za(j3,j4)*zb(j5,j6))
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& *((s(j1,j4)-s(j2,j3))
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& *(zab(j1,j2,j6)*delta12-zab(j1,j5,j6)*delta56)
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& +zab2(j1,j3,j4,j2)*(zab(j2,j1,j6)*delta12-zab(j2,j5,j6)*delta56))
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& +2*zab(j2,j1,j3)*zab2(j5,j1,j2,j6)*(s(j1,j4)-s(j2,j3)))
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return
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end
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