static double sigma_gauss(double PcmIn)
{ double r;
if(kin22(PcmIn,pmass)) return 0.;
_nsub_=nsub;
r=gauss(dSigma_dCos,-1.,1.,5);
if(r<0) { neg_cs_flag=1;r=0;}
return r;
}
static double sigma_simpson(double PcmIn)
{ double r;
if(kin22(PcmIn,pmass)) return 0;
_nsub_=nsub;
r= simpson(dSigma_dCos,-1.,1,0.3*eps);
if(r<0) { neg_cs_flag=1;r=0;}
/*
printf("PcmIN=%E sigma=%E\n", PcmIn, r*3.8937966E8);
*/
return r;
}
static double sigma_gauss(double PcmIn)
{ double r;
if(kin22(PcmIn,pmass)) return 0.;
_nsub_=nsub;
r=gauss(dSigma_dCos,-1.,1.,5);
if(r<0) { neg_cs_flag=1;r=0;}
#ifdef IMPROVE
improveCrossSection(PDGnum[0],PDGnum[1],PDGnum[2],PDGnum[3],PcmIn,&r);
#endif
return r;
}
double cs22(numout * cc, int nsub, double P, double cos1, double cos2 , int * err)
{
int i;
double pmass[4];
for(i=1;i<=cc->interface->nvar;i++) if(cc->link[i]) cc->interface->va[i]=*(cc->link[i]);
GG=sqrt(4*M_PI*parton_alpha(GGscale));
if( cc->interface->calcFunc()>0 ) {*err=4; return 0;}
*(cc->interface->gtwidth)=0;
*(cc->interface->twidth)=0;
*(cc->interface->gswidth)=1;
for(i=0;i<4;i++) cc->interface->pinf(nsub,1+i,pmass+i,NULL);
*err=0;
sqme22=cc->interface->sqme;
nsub22=nsub;
if(kin22(P,pmass)) return 0; else return 3.8937966E8*simpson(dSigma_dCos,cos1,cos2,0.3*eps);
}
static double sigma_simpson(double PcmIn)
{ double r;
if(kin22(PcmIn,pmass)) return 0;
_nsub_=nsub;
r= simpson(dSigma_dCos,-1.,1.,0.3*eps);
if(r<0) { neg_cs_flag=1;r=0;}
#ifdef IMPROVE
improveCrossSection(PDGnum[0],PDGnum[1],PDGnum[2],PDGnum[3],PcmIn,&r);
#endif
/*
printf("PcmIN=%E sigma=%E\n", PcmIn, r*3.8937966E8);
*/
return r;
}
static double s_integrandT_(double sqrtS )
{ double sv_tot,t,bess, x1,x2,y;
double ms,md,PcmIn;
double Rm;
ms = M1 + M2;
if(ms>=sqrtS) return 0;
x1=M1/T_; x2=M2/T_; y=sqrtS/T_;
if(y-x1-x2>50) return 0;
md = M1 - M2;
PcmIn = sqrt((sqrtS-ms)*(sqrtS+ms)*(sqrtS-md)*(sqrtS+md))/(2*sqrtS);
kin22(PcmIn,pmass);
sv_tot=simpson(dSigma_dCos,-1.,1.,1E-3);
bess= sqrt(2*x1*x2/y/M_PI)*exp(-(y-x1-x2))*K1pol(1/y)/(K2pol(1/x1)*K2pol(1/x2));
Rm=PcmIn*sqrtS/M1/M2;
return bess*Rm*Rm*sv_tot/T_;
}
