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my_setpara.f
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subroutine my_setpara
c***********************************************************************
c !: This subroutine is similar to setpara (Mad v4) and sets up
c the HELAS couplings of the STANDARD MODEL without reading a card.
c Original subroutine left in file couplings.f.orig
c***********************************************************************
implicit none
c
c local
c
!: character*(*) param_name
logical readlha
integer i
real*8 dum
c
c common file with the couplings
c
include 'coupl.inc'
c
c local
c
double precision v
double precision ee, ee2, ez, ey, sw, cw, sc2, sin2w, wm
double precision gwne, gwud, lambda, lam4, xt, rew, rqcd
double precision alphas, alfa, alfaw, mfrun
external alphas, alfa, alfaw, mfrun
c
c Common to lh_readin and printout
c
double precision alpha, gfermi, alfas
double precision mtMS,mbMS,mcMS,mtaMS!MSbar masses
double precision Vud,Vus !CKM matrix elements
common/values/ alpha,gfermi,alfas,
& mtMS,mbMS,mcMS,mtaMS,
& Vud
c
c constants
c
double complex ci
parameter( ci = ( 0.0d0, 1.0d0 ) )
double precision Zero, One, Two, Three, Four, Half, Rt2
parameter( Zero = 0.0d0, One = 1.0d0, Two = 2.0d0 )
parameter( Three = 3.0d0, Four = 4.0d0, Half = 0.5d0 )
parameter( Rt2 = 1.414213562d0 )
double precision Pi, Fourpi
parameter( Pi = 3.14159265358979323846d0 )
parameter( Fourpi = Four * Pi )
c
c------------------------------------------
c Start calculating the couplings for HELAS
c------------------------------------------
c
G = DSQRT(4d0*PI*ALFAS) ! use setting of the param_card.dat @ NLO
c
c Strong coupling
c
c As a rule we first check if a pdf has been chosen in the
c run_card.dat (which has been already read at this stage).
c If there pdfs in the initial state, then the alpha_s(MZ) used
c is set to the corresponding value.
GG(1) = -G
GG(2) = -G
c
c auxiliary local values
c
wm = sqrt(zmass**2/Two+
$ sqrt(zmass**4/Four-Pi/Rt2*alpha/gfermi*zmass**2))
sin2w = One-(wm/zmass)**2
cw = sqrt( One - sin2w )
ee2 = alpha * Fourpi
sw = sqrt( sin2w )
ee = sqrt( ee2 )
ez = ee/(sw*cw)
ey = ee*(sw/cw)
sc2 = sin2w*( One - sin2w )
v = Two*wm*sw/ee ! the wmass is used to calculate v
lambda = hmass**2 / (Two * v**2)
c
c vector boson couplings
c
gw = ee/sw
gwwa = ee
gwwz = ee*cw/sw
c
c gauge & higgs boson coupling constants
c
gwwh = dcmplx( ee2/sin2w*Half*v, Zero )
gzzh = dcmplx( ee2/sc2*Half*v, Zero )
ghhh = dcmplx( -hmass**2/v*Three, Zero )
gwwhh = dcmplx( ee2/sin2w*Half, Zero )
gzzhh = dcmplx( ee2/sc2*Half, Zero)
ghhhh = ghhh/v
c
c fermion-fermion-vector couplings
c
gal(1) = dcmplx( ee , Zero )
gal(2) = dcmplx( ee , Zero )
gau(1) = dcmplx( -ee*Two/Three, Zero )
gau(2) = dcmplx( -ee*Two/Three, Zero )
gad(1) = dcmplx( ee/Three , Zero )
gad(2) = dcmplx( ee/Three , Zero )
gwf(1) = dcmplx( -ee/sqrt(Two*sin2w), Zero )
gwf(2) = dcmplx( Zero , Zero )
gzn(1) = dcmplx( -ez*Half , Zero )
gzn(2) = dcmplx( Zero , Zero )
gzl(1) = dcmplx( -ez*(-Half + sin2w) , Zero )
gzl(2) = dcmplx( -ey , Zero )
gzu(1) = dcmplx( -ez*( Half - sin2w*Two/Three), Zero )
gzu(2) = dcmplx( ey*Two/Three , Zero )
gzd(1) = dcmplx( -ez*(-Half + sin2w/Three) , Zero )
gzd(2) = dcmplx( -ey/Three , Zero )
c
c fermion-fermion-Higgs couplings (complex) hff(2)
c
c NOTE: the running mass is evaluated @ the same order
c nloop of alpha_s set by the PDF choice
c
if(mtMS.gt.1d0) then
ghtop(1) = dcmplx( -mtMS/v, Zero )
else
ghtop(1) = dcmplx( Zero,Zero)
endif
ghtop(2) = ghtop(1)
if(mbMS.gt.1d0) then
ghbot(1) = dcmplx( -mbMS/v, Zero )
else
ghbot(1) = dcmplx( Zero, Zero )
endif
ghbot(2) = ghbot(1)
if(mcMS.gt.1d0) then
ghcha(1) = dcmplx( -mcMS/v, Zero )
else
ghcha(1) = dcmplx( Zero, Zero )
endif
ghcha(2) = ghcha(1)
ghtau(1) = dcmplx( -mtaMS/v, Zero )
ghtau(2) = ghtau(1)
c
c CKM matrix:
c symmetric 3x3 matrix, Vud=Vcs, Vus=Vcd Vcb=Vub=0
c
c >>>>>>>>>>>>>>>***** NOTE****<<<<<<<<<<<<<<<<<<<<<<<<<
c these couplings matter only when interaction_CKM.dat
c is used to generate all the diagrams with off-diagonal
c couplings. The default of MadEvent is a diagonal
c CKM matrix.
Vus=DSQRT(1d0-Vud**2)
do i=1,2
gwfc(i) = gwf(i)*Vud
gwfs(i) = gwf(i)*Vus
gwfm(i) =-gwf(i)*Vus
enddo
c---------------------------------------------------------
c Set Photon Width to Zero, used by symmetry optimization
c---------------------------------------------------------
awidth = 0d0
c----------------------------
c end subroutine coupsm
c----------------------------
return
end