double AMEGIC::Single_Process_External::DSigma(const ATOOLS::Vec4D_Vector &_moms,bool lookup)
{
m_lastxs = 0.;
if (p_partner == this) {
m_lastxs = m_Norm * operator()((ATOOLS::Vec4D*)&_moms.front());
}
else {
if (lookup && p_partner->m_lookup)
m_lastxs = p_partner->LastXS()*m_sfactor;
else m_lastxs = m_Norm * p_partner->operator()((ATOOLS::Vec4D*)&_moms.front())*m_sfactor;
}
return m_lastxs;
}
double Decay_Channel::Differential(ATOOLS::Vec4D_Vector& momenta, bool anti,
METOOLS::Spin_Density* sigma,
const std::vector<ATOOLS::Particle*>& p)
{
Poincare labboost(momenta[0]);
labboost.Boost(momenta[0]);
Channels()->GeneratePoint(&momenta.front(),NULL);
Channels()->GenerateWeight(&momenta.front(),NULL);
labboost.Invert();
for (size_t i(0); i<momenta.size(); ++i) labboost.Boost(momenta[i]);
double dsigma_lab=ME2(momenta, anti, sigma, p);
return dsigma_lab*Channels()->Weight();
}
double AMEGIC::Single_Process_MHV::DSigma(const ATOOLS::Vec4D_Vector &_moms,bool lookup)
{
m_lastxs = 0.;
if (m_nin==2) {
for (size_t i=0;i<m_nin+m_nout;i++) {
if (_moms[i][0]<m_flavs[i].Mass()) return 0.0;
}
}
if (m_nin==1) {
for (size_t i=m_nin;i<m_nin+m_nout;i++) {
if (_moms[i][0]<m_flavs[i].Mass()) return 0.0;
}
}
if (p_partner == this) {
m_lastxs = m_Norm * operator()((ATOOLS::Vec4D*)&_moms.front());
}
else {
if (lookup && p_partner->m_lookup) m_lastxs = p_partner->LastXS()*m_sfactor;
else m_lastxs = m_Norm * p_partner->operator()((ATOOLS::Vec4D*)&_moms.front())*m_sfactor;
}
return m_lastxs;
}