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77 lines
2.1 KiB

!
! SPDX-License-Identifier: GPL-3.0-or-later
! Copyright (C) 2019-2022, respective authors of MCFM.
!
subroutine qqb_Hg_z(p,z)
implicit none
include 'types.f'
c***********************************************************************
c Author: John M. Campbell *
c February, 2002 *
c***********************************************************************
include 'constants.f'
include 'mxpart.f'
include 'qcdcouple.f'
include 'scale.f'
include 'PR_new.f'
include 'agq.f'
integer:: is
real(dp):: z,p(mxpart,4),dot
real(dp):: ii_qg,ii_gq,fi_qq,
& ii_gg,if_gg,ii_qq,if_qq
real(dp):: xl12,xl15,xl25
xl12=log(+two*dot(p,1,2)/musq)
xl15=log(-two*dot(p,1,5)/musq)
xl25=log(-two*dot(p,2,5)/musq)
c--- 2-quark terms
c--- sum over regular and plus terms
do is=1,3
c--- No (q,qb) terms here
c--- (q,g)
Q2(g,g,q,is)=ason4pi*xn
& *(ii_gg(z,xl12,is)
& +if_gg(z,xl25,is)+fi_qq(z,xl25,is))
Q1(q,q,g,is)=ason4pi*xn
& *(ii_qq(z,xl12,is)
& -(if_qq(z,xl15,is)+fi_qq(z,xl15,is))/xnsq)
c--- (qb,g)
Q2(g,g,a,is)=Q2(g,g,q,is)
Q1(a,a,g,is)=Q1(q,q,g,is)
c--- (g,q)
Q1(g,g,q,is)=ason4pi*xn
& *(ii_gg(z,xl12,is)
& +if_gg(z,xl15,is)+fi_qq(z,xl15,is))
Q2(q,q,g,is)=ason4pi*xn
& *(ii_qq(z,xl12,is)
& -(if_qq(z,xl25,is)+fi_qq(z,xl25,is))/xnsq)
c--- (g,qb)
Q1(g,g,a,is)=Q1(g,g,q,is)
Q2(a,a,g,is)=Q2(q,q,g,is)
c--- (g,g)
Q1(q,g,g,is)=ason4pi*2._dp*tr*ii_qg(z,xl12,is)
Q1(a,g,g,is)=Q1(q,g,g,is)
Q2(q,g,g,is)=Q1(q,g,g,is)
Q2(a,g,g,is)=Q1(q,g,g,is)
enddo
c--- 4-quark terms
do is=1,3
Q1(g,q,q,is)=ason4pi*(xn-1._dp/xn)*ii_gq(z,xl12,is)
Q2(g,q,q,is)=ason4pi*(xn-1._dp/xn)*ii_gq(z,xl12,is)
Q1(g,a,a,is)=Q1(g,q,q,is)
Q2(g,a,a,is)=Q2(g,q,q,is)
Q1(g,a,q,is)=Q1(g,q,q,is)
Q2(g,a,q,is)=Q2(g,q,q,is)
Q1(g,q,a,is)=Q1(g,q,q,is)
Q2(g,q,a,is)=Q2(g,q,q,is)
enddo
return
end