c======================================================================= c If you copy this code, please send a message to c RIDOLFI@VXCERN.CERN.CH c or to c MLM@VXCERN.CERN.CH c so that we can keep you informed of upgrades or modifications. c======================================================================= implicit real*8 (a-h,o-z) common/prcpar/st1,casq common/beams/s,sthr common/bveg1/xl(10),xu(10),acc,ndim,ncall,itmx,nprn external radsig pi=acos(-1.d0) c c Initialize parameters for Vegas do j=1,10 xl(j) = 0 xu(j) = 1 enddo acc = -1 ndim = 1 ncall = 10000 itmx = 4 1 write(*,*)'enter sqrt(s),m(st1),th(deg)' read(*,*)sr,st1,th if(sr.lt.0) stop s=sr**2 sthr=4*st1**2 casq=cos(th*pi/180.d0)**2 c no isr xsect0=sig(s) c with isr call vegas(radsig,xsect1,sd,chisq) c output write(*,*)' m(stop) = ',st1,'GeV',' theta=',th write(*,*)' xsec no isr =',xsect0,'pb' write(*,*)' xsec with isr =',xsect1,'pb' if(sr.ne.srold) then write(1,100) sr srold=sr endif write(1,101) st1,th write(1,102) xsect0 write(1,103) xsect1 goto 1 100 format(' Ecm = ',g10.4,'GeV') 101 format(' m(stop) = ',g10.4,'GeV',' theta=',g10.4) 102 format(' xsec no isr (pb) =',g10.4) 103 format(' xsec with isr (pb) =',g10.4) end c------------------------------------------------------------------------- function sig(s) c Computes c sigma(e+e- -> stop1 stop1) c including photon and Z exchange and finite Z width effects. c Input parameters: sqrt(s) and cos(alpha)**2 c Checked with Phys. Lett. B252 (1990) 127 c------------------------------------------------------------------------- implicit real*8 (a-h,o-z) common/prcpar/st1,casq parameter(qf=2.d0/3.d0,gz=2.5d0,xmz=91.2d0,s2w=0.232d0) c2w=1-s2w aem=alfa(s) xlam=.270d0 as = alfas(s,xlam,5) pi=acos(-1.d0) c attenzione: sezione d'urto in pb hc2=3.8937966d8 fac=pi*aem**2*hc2/s gg=qf**2 propzz=s**2/((s-xmz**2)**2+xmz**2*gz**2) propgz=s*(s-xmz**2)/((s-xmz**2)**2+xmz**2*gz**2) den=4*c2w*s2w rnzz=(-casq/2+2*s2w/3)**2*(1+(1-4*s2w)**2) rngz=2*qf*(-casq/2+2*s2w/3)*(-1+4*s2w) zz=rnzz/den**2*propzz pz=rngz/den*propgz rest=fac*(gg+zz+pz) if(st1.lt.(sqrt(s)/2))then beta=sqrt(1-4*st1**2/s) sig=beta**3*rest c include qcd corrections sig = sig - * (1+4/3d0/pi*as*(pi**2/2d0/beta-(1+beta)/2d0*(pi**2/2d0-3))) else sig=0 endif end function alfas(q2,xlam,inf) implicit real*8 (a-h,o-z) data olam/0.d0/,pi/3.14159d0/ data xmb/5.d0/,xmc/1.5d0/ if(xlam.ne.olam) then olam = xlam b5 = (33-2*5)/pi/12 bp5 = (153 - 19*5) / pi / 2 / (33 - 2*5) b4 = (33-2*4)/pi/12 bp4 = (153 - 19*4) / pi / 2 / (33 - 2*4) b3 = (33-2*3)/pi/12 bp3 = (153 - 19*3) / pi / 2 / (33 - 2*3) xlc = 2 * log(xmc/xlam) xlb = 2 * log(xmb/xlam) xllc = log(xlc) xllb = log(xlb) c45 = 1/( 1/(b5 * xlb) - xllb*bp5/(b5 * xlb)**2 ) # - 1/( 1/(b4 * xlb) - xllb*bp4/(b4 * xlb)**2 ) c35 = 1/( 1/(b4 * xlc) - xllc*bp4/(b4 * xlc)**2 ) # - 1/( 1/(b3 * xlc) - xllc*bp3/(b3 * xlc)**2 ) + c45 endif q = sqrt(q2) xlq = 2 * log( q/xlam ) xllq = log( xlq ) nf = inf if( nf .lt. 0) then if( q .gt. xmb ) then nf = 5 elseif( q .gt. xmc ) then nf = 4 else nf = 3 endif endif if ( nf .eq. 5 ) then alfas = 1/(b5 * xlq) - bp5/(b5 * xlq)**2 * xllq elseif( nf .eq. 4 ) then alfas = 1/( 1/(1/(b4 * xlq) - bp4/(b4 * xlq)**2 * xllq) + c45 ) elseif( nf .eq. 3 ) then alfas = 1/( 1/(1/(b3 * xlq) - bp3/(b3 * xlq)**2 * xllq) + c35 ) else print *,'error in alfa: unimplemented # of light flavours',nf stop endif return end