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c**********************************************************************
double precision function totfun(zup,papawt)
implicit double precision (a-h,o-z)
implicit integer (i-n)
#include "inclcon.h"
c...pythia common block.
common/pydat1/mstu(200),paru(200),mstj(200),parj(200)
common/pypars/mstp(200),parp(200),msti(200),pari(200)
parameter (maxnup=500)
common/hepeup/nup,idprup,xwgtup,scalup,aqedup,aqcdup,idup(maxnup),
&istup(maxnup),mothup(2,maxnup),icolup(2,maxnup),pup(5,maxnup),
&vtimup(maxnup),spinup(maxnup)
save /hepeup/
c...user transformation.
double complex colmat,bundamp
common/upcom/ecm,pmbc,pmb,pmc,fbcc,pmomup(5,8),
& colmat(10,64),bundamp(4),pmomzero(5,8)
c...transform the bound state information.
common/counter/ibcstate,nev
common/rconst/pi
common/ptpass/ptmin,ptmax,crossmax,etamin,etamax,
& smin,smax,ymin,ymax,psetamin,psetamax
common/confine/ptcut,etacut
common/colflow/amp2cf(10),smatval
c...parameters transformtion used in totfun()
common/funtrans/nq2,npdfu
c...to get the subprocess cross-section.
common/subopen/subfactor,subenergy,isubonly
c...generate---switch for full events.
logical generate
common/genefull/generate
c...to get the distribution of an extra factor z=(2(k1+k2).p_bc)/shat.
common/extraz/zfactor,zmin,zmax
common/outpdf/ioutpdf,ipdfnum
common/intinip/iinip
common/intinif/iinif
c...for transform the subprocess information, i.e., whether using
c...the subprocess q\bar{q}->bc+b+\bar{c} to generate events.
common/qqbar/iqqbar,iqcode
dimension xpp(-25:25),xppbar(-25:25),zup(7),pboo(4),pc(4),pl(4)
data conv/3.8938573d+8/ !pb
common /ppp/ pp(4,40),guv(4)
c------------------------------------------------
totfun=0.0d0
phase = 0.
c------------------------------------------------
if(isubonly.eq.1) then
x1=subfactor
x2=subfactor
else
taumin =((pmbc+pmb+pmc)/ecm)**2
taumax =1.0d0
tau=(taumax-taumin)*zup(6)+taumin
yymin= dlog(dsqrt(tau))
yymax=-dlog(dsqrt(tau))
yy =(yymax-yymin)*zup(7)+yymin
x1 =dsqrt(tau)*exp(yy)
x2 =dsqrt(tau)*exp(-yy)
end if
c-------------------------------------------------
c... gluon 1, in lab
pup(1,1)= 0.0d0
pup(2,1)= 0.0d0
pup(3,1)= ecm*x1/2.0d0
pup(4,1)= ecm*x1/2.0d0
pup(5,1)= 0.0d0
c... gluon 2, in lab
pup(1,2)= 0.0d0
pup(2,2)= 0.0d0
pup(3,2)=-ecm*x2/2.0d0
pup(4,2)= ecm*x2/2.0d0
pup(5,2)= 0.0d0
c...change momtuma of the final particals into lab coordinate system.
c...the original one getting from phase_gen is result for c.m. system.
do i=1,4
pboo(i)=pup(i,1)+pup(i,2)
end do
do 101, i=1,3
do j=1,4
pc(j)=pmomup(j,i+2)
end do
call lorentz(pboo,pc,pl)
do j=1,4
pmomup(j,i+2)=pl(j)
end do
101 continue
c...set up kinematics of the out going particles: bc, b and c~.
do i=3,5
do j=1,5
pup(j,i)=pmomup(j,i)
end do
end do
c...for s-wave bound state, taking non-relativistic approximation.
do i=1,5
pmomup(i,6)=pmb/(pmb+pmc)*pmomup(i,3)
pmomup(i,7)=pmc/(pmb+pmc)*pmomup(i,3)
end do
c...incoming gluon momenta used in s_amp.for.
do i=1,2
do j=1,5
pmomup(j,i)=pup(j,i)
end do
end do
c...this part is from the inner part of pythia subroutine pyp().
ptbc =dsqrt(pup(1,3)**2+pup(2,3)**2)
pr =max(1.0d-16,pup(5,3)**2+pup(1,3)**2+pup(2,3)**2)
prs =max(1.0d-16,pup(1,3)**2+pup(2,3)**2)
eta =sign(dlog(min((dsqrt(pr+pup(3,3)**2)+dabs(pup(3,3)))
& /dsqrt(pr),1.0d+20)),pup(3,3))
pseta =sign(dlog(min((dsqrt(prs+pup(3,3)**2)+dabs(pup(3,3)))
& /dsqrt(prs),1.0d+20)),pup(3,3))
c...other confinement can also be added here.
if(ptbc.lt.ptcut .or. abs(eta).gt.etacut) then
if (generate) then
do ii=1,10
amp2cf(ii)=0.0d0
end do
end if
smatval=0.0d0
return
end if
c...energy scale.
if(nq2.eq.1) q2 =x1*x2*ecm**2/4.0d0
if(nq2.eq.2) q2 =x1*x2*ecm**2
if(nq2.eq.3.or.nq2.eq.8) q2 =ptbc**2.0d0+pup(5,3)**2
if(nq2.eq.4) then
q=0.0d0
do i=3,5
q=q+dsqrt(pup(1,i)**2+pup(2,i)**2+pup(5,i)**2)
end do
q2=q**2
end if
if(nq2.eq.5) then
q=0.0d0
do i=3,5
q=q+dsqrt(pup(1,i)**2.0d0+pup(2,i)**2.0d0+pup(5,i)**2.0d0)
end do
q2=(q/3.0d0)**2.0d0
end if
if(nq2.eq.6.or.nq2.eq.7) then
q2=pmb**2+pup(1,4)**2+pup(2,4)**2
end if
c...this is the energy scale used in gouz's program
if(nq2.eq.9) then
q2=4.0d0*pmb**2
end if
alps = 0.00
alps2 = 0.00
c...get the value of alphas. all are in leading order.
if(ioutpdf.eq.1) then
if(ipdfnum.eq.100) alps =alpgrv(q2,1)*4*pi
if(ipdfnum.eq.200) alps =alpmsrt(dsqrt(q2),0.220d0,0)
if(ipdfnum.eq.300) alps =alpcteq(q2,1)*4*pi
else
alps =pyalps(q2)
end if
c...two energy scale for alphas.
c...alphas^4=alphas^2(\mu_b**2)*alphas^2(\mu_c**2).
if(nq2.eq.6.or.nq2.eq.8) then
alps1=alps
if(ioutpdf.eq.1) then
q2=4.0d0*pmc**2.0d0
if(ipdfnum.eq.100) alps2 =alpgrv(q2,1)*4*pi
if(ipdfnum.eq.200) alps2 =alpmsrt(dsqrt(q2),0.22d0,0)
if(ipdfnum.eq.300) alps2 =alpcteq(q2,1)*4*pi
else
alps2 =pyalps(4.0d0*pmc**2.0d0)
end if
alps =dsqrt(alps1*alps2)
end if
c...store scale choice and alphas.
scalup=dsqrt(q2)
aqcdup=alps
if(isubonly.eq.0) then
if(ioutpdf.eq.0) then
c...tevatron
c...evaluate parton distribution for (g1<--p,g2<---p~)
if(npdfu.eq.1) then
call pypdfu(2212,x1,q2,xpp)
call pypdfu(-2212,x2,q2,xppbar)
end if
c...lhc
c...evaluate parton distribution for (g1<--p,g2<---p)
if(npdfu.eq.2) then
call pypdfu(2212,x1,q2,xpp)
call pypdfu(2212,x2,q2,xppbar)
end if
else
if(ipdfnum.eq.100) then
call grv98pa(1, x1, q2, uv, dv, us, ds, ss, gl1)
call grv98pa(1, x2, q2, uv, dv, us, ds, ss, gl2)
if(iqqbar.eq.0) then
xpp(21)=gl1
xppbar(21)=gl2
else
if(iqcode.eq.1) then
if(npdfu.eq.1) then !tevatron
xpp(iqcode)=uv+us
xpp(-iqcode)=us
xppbar(iqcode)=uv+us
xppbar(-iqcode)=us
end if
if(npdfu.eq.2) then !lhc
xpp(iqcode)=uv+us
xpp(-iqcode)=us
xppbar(iqcode)=us
xppbar(-iqcode)=uv+us
end if
end if
if(iqcode.eq.2) then
if(npdfu.eq.1) then !tevatron (u-p,~u-~p and u-~p,~u-p)
xpp(iqcode)=dv+ds
xpp(-iqcode)=ds
xppbar(iqcode)=dv+ds
xppbar(-iqcode)=ds
end if
if(npdfu.eq.2) then !lhc (u-p,~u-p and u-p,~u-p)
xpp(iqcode)=dv+ds
xpp(-iqcode)=ds
xppbar(iqcode)=ds
xppbar(-iqcode)=dv+ds
end if
end if
if(iqcode.eq.3) then ! the same for tevatron or lhc
xpp(3)=2.0d0*ss
xppbar(3)=2.0d0*ss
end if
end if
end if
if(ipdfnum.eq.200) then
qq=dsqrt(q2)
call mrstlo(x1,qq,1,upv,dnv,usea,dsea,str,chm,bot,glu1)
call mrstlo(x2,qq,1,upv,dnv,usea,dsea,str,chm,bot,glu2)
if(iqqbar.eq.0) then
xpp(21)=glu1
xppbar(21)=glu2
else
if(iqcode.eq.1) then
if(npdfu.eq.1) then !tevatron (u-p,~u-~p and u-~p,~u-p)
xpp(iqcode)=upv+usea
xpp(-iqcode)=usea
xppbar(iqcode)=upv+usea
xppbar(-iqcode)=usea
end if
if(npdfu.eq.2) then !lhc (u-p,~u-p and u-p,~u-p)
xpp(iqcode)=upv+usea
xpp(-iqcode)=usea
xppbar(iqcode)=usea
xppbar(-iqcode)=upv+usea
end if
end if
if(iqcode.eq.2) then
if(npdfu.eq.1) then !tevatron (u-p,~u-~p and u-~p,~u-p)
xpp(iqcode)=dnv+dsea
xpp(-iqcode)=dsea
xppbar(iqcode)=dnv+dsea
xppbar(-iqcode)=dsea
end if
if(npdfu.eq.2) then !lhc (u-p,~u-p and u-p,~u-p)
xpp(iqcode)=dnv+dsea
xpp(-iqcode)=dsea
xppbar(iqcode)=dsea
xppbar(-iqcode)=dnv+dsea
end if
end if
if(iqcode.eq.3) then
xpp(3)=str*2.0d0
xppbar(3)=str*2.0d0
end if
end if
end if
if(ipdfnum.eq.300) then
qq=dsqrt(q2)
c...cteq6l.
if(iqqbar.eq.0) then
xpp(21) =ctq6pdf(0,x1,qq)
xppbar(21)=ctq6pdf(0,x2,qq)
else
if(npdfu.eq.1) then !tevatron
xpp(iqcode)=ctq6pdf(iqcode,x1,qq)
xpp(-iqcode)=ctq6pdf(-iqcode,x1,qq)
xppbar(iqcode)=ctq6pdf(iqcode,x2,qq)
xppbar(-iqcode)=ctq6pdf(-iqcode,x2,qq)
end if
if(npdfu.eq.2) then !lhc
xpp(iqcode)=ctq6pdf(iqcode,x1,qq)
xpp(-iqcode)=ctq6pdf(-iqcode,x1,qq)
xppbar(iqcode)=ctq6pdf(-iqcode,x2,qq)
xppbar(-iqcode)=ctq6pdf(iqcode,x2,qq)
end if
end if
end if
end if
end if
c...this ensure the rightness of the extrapolation of the pdf.
c...(by using the pdfs, sometimes it will get negative value)
if(xpp(21).lt.1.0d-16) xpp(21)=0.0d0
if(xppbar(21).lt.1.0d-16) xppbar(21)=0.0d0
if(iqqbar.eq.1) then
if(xpp(iqcode).lt.1.0d-16) xpp(iqcode)=0.0d0
if(xppbar(iqcode).lt.1.0d-16) xppbar(iqcode)=0.0d0
if(xpp(-iqcode).lt.1.0d-16) xpp(-iqcode)=0.0d0
if(xppbar(-iqcode).lt.1.0d-16) xppbar(-iqcode)=0.0d0
end if
c...for the sub-process, taking the constant alphas value.
if(isubonly.eq.1) alps=0.20d0
c...if not generate s-wave, go to the part for p-wave.
if(ibcstate.eq.3) goto 1005
if(ibcstate.eq.4) goto 1005
if(ibcstate.eq.5) goto 1005
if(ibcstate.eq.6) goto 1005
c...common factor for s-wave states.
phase =papawt*alps**4.0d0/(2.0d0**11*pi*3.0d0*dotup(1,2))
c...first to get the square of the amplitude.
c...note 1) the momenta inputed into this subroutine is pmomup(j,i):
c...bc+: i=3, b: i=4, ~c: i=5;
c...j=1: p_x; j=2: p_y; j=3: p_z; j=4: e; j=5: mass; 2) all the momenta
c...now are in the lab system, you may directly get the momenta in c.m.s
c...of gluon-gluon subsystem before running lorentz transformation used
c...above. the cross-section will not change under the cordinate
c...transformation. 3) sigscl and sigvct, after calling this subroutine,
c...is not the final cross-section, we need to add some coefficients.
c...there we don't need an extra q in xsection_bcy, because 4) the momenta
c...are now also stored in pup(j,i), which is transformed according to
c...a pythia common block.
call xsection(sigscl,sigvct)
c...get the right phase for the subprocess: q+~q->bc+b+~c from
c...the same precedure of subprocess g+g->bc+b+~c.
if(iqqbar.eq.1) then
phase=phase*(2.0d0**6/3.0d0**2)
end if
c...the correct cross-section for the subprocess to a particular particle
c...momenta.
sigscl=conv*phase*sigscl
sigvct=conv*phase*sigvct
sigcross = 0.0
if(ibcstate.eq.1) sigcross=sigscl
if(ibcstate.eq.2) sigcross=sigvct
c...get the cross-section for s-wave.
if(isubonly.eq.0) then
if(iqqbar.eq.0) then
totfun =sigcross*xpp(21)*xppbar(21)/x1/x2
if(ioutpdf.eq.1 .and. ipdfnum.eq.300) then
totfun=sigcross*xpp(21)*xppbar(21)
end if
else
totfun =sigcross*(xpp(iqcode)*xppbar(iqcode)+
& xpp(-iqcode)*xppbar(-iqcode))/x1/x2
if(ioutpdf.eq.1 .and. ipdfnum.eq.300) then
totfun =sigcross*xpp(iqcode)*xppbar(iqcode)
end if
end if
else
totfun =sigcross
end if
c...getting an extra distribution about z=(2(k1+k2).p_bc)/shat.
zfactor=2.0d0*(dotup(1,3)+dotup(2,3))/(x1*x2*ecm**2.0d0)
c...the following is only to eliminate the numerical uncerntainty,
c...which in principle does not needed. however we added here
c...to avoid some very particular cases.
if(totfun.lt.1.0d-16) totfun=1.0d-16
return
c************************************************
c...the following is for the p-wave states.
c************************************************
1005 continue
if(ibcstate.ne.1.and.ibcstate.ne.2) then
c...the p-wave part is adopted from fdc program and here
c...is to make all the variable consistent to fdc.
c...in the lab system.
c...pp(1,i)=e=pup(4,i);
c...pp((2,3,4),i)=(p_x,p_y,p_z)=pup((1,2,3),i).
c...pp(4)=pup(5)--b quark; pp(5)=pup(4)--\bar{c} quark.
do i=1,3
pp(2,i)=pup(1,i)
pp(3,i)=pup(2,i)
pp(4,i)=pup(3,i)
pp(1,i)=pup(4,i)
end do
pp(2,4)=pup(1,5)
pp(3,4)=pup(2,5)
pp(4,4)=pup(3,5)
pp(1,4)=pup(4,5)
pp(2,5)=pup(1,4)
pp(3,5)=pup(2,4)
pp(4,5)=pup(3,4)
pp(1,5)=pup(4,4)
c...this is an overall color factor, where the average over
c...the initial gluons have been included, i.e. the factor
c...(1/2**6) has been included into cfact, i.e.
c... cfact=(33.0d0/2.0d0)/(2.0d0**6)
cfact=0.2578125d0
c...this is to get constants for the gluon coupling constant g.
g3=dsqrt(4.0d0*pi*alps)
ampofpw = 0.0
if(ibcstate.eq.3) then
ampofpw=amps2_1p1()
phase=papawt*cfact*g3**8/(2.0d0**9*pi**5*dotup(1,2))
end if
if(ibcstate.eq.4) then
ampofpw=amps2_3p0()
phase=papawt*cfact*g3**8/(2.0d0**9*pi**5*dotup(1,2))
end if
if(ibcstate.eq.5) then
ampofpw=amps2_3p1()
phase=papawt*cfact*g3**8/(2.0d0**9*pi**5*dotup(1,2))
end if
if(ibcstate.eq.6) then
ampofpw=amps2_3p2()
phase=papawt*cfact*g3**8/(2.0d0**9*pi**5*dotup(1,2))
end if
c...get the cross-sectin for p-wave.
if(isubonly.eq.1) then
totfun=conv*phase*ampofpw
else
totfun =conv*phase*ampofpw*xpp(21)*xppbar(21)/x1/x2
if(ioutpdf.eq.1 .and. ipdfnum.eq.300) then
totfun=conv*phase*ampofpw*xpp(21)*xppbar(21)
end if
end if
end if
c...getting an extra distribution about z=(2(k1+k2).p_bc)/shat.
zfactor=2.0d0*(dotup(1,3)+dotup(2,3))/(x1*x2*ecm**2.0d0)
c...the following is only to eliminate the numerical uncerntainty,
c...which in principle does not needed. however we added here
c...to avoid some very particular cases.
if(totfun.lt.1.0d-16) totfun=1.0d-16
return
end
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