Exemplo n.º 1
0
Arquivo: SM_U1_B.C Projeto: ktf/sherpa
void SM_U1_B::FillSpectrum(const PDF::ISR_Handler_Map& isr) {
  p_dataread->RereadInFile();
  p_constants->insert(make_pair(string("M_Z'"),    
				p_dataread->GetValue<double>("M_Z'",-1.)));
  p_constants->insert(make_pair(string("g'_1"),    
				p_dataread->GetValue<double>("g'_1",0.)));

  double MZprime(ScalarConstant(string("M_Z'"))),GZprime(0.),inc;
  double g1prime(sqr(ScalarConstant(std::string("g'_1"))));
  FixMix();
  msg_Out()<<"Calculate width for Z' with mass = "<<MZprime<<" GeV.\n";

  for (short int i=1;i<=6;i++) {
    Flavour quark = Flavour((kf_code)(i));
    double  massq = quark.HadMass(); 
    if (!quark.IsOn() || !quark.Strong()) continue;
    if (i%2) {
      if (2.*massq>MZprime) continue;
      GZprime += inc = 
	3.*MZprime*g1prime/(24.*M_PI)*pow(1.-sqr(2.*massq/MZprime),3./2.);
      msg_Out()<<"   Add Z' --> "<<quark<<"+"<<quark.Bar()<<" ("<<i<<"), "
	       <<" add "<<inc<<" GeV.\n";
    }
    else {
      double M2 = MZprime*MZprime, mq2 = massq*massq;
      for (short int j=2;j<=7;j+=2) {
	Flavour anti = Flavour((kf_code)(j)).Bar();
	if (!anti.IsOn() || !anti.Strong()) continue;
	double massa  = anti.HadMass(), ma2 = massa*massa; 
	if (massq+massa>MZprime) continue;
	Complex mix   = ComplexMatrixElement(std::string("UpMix"),i/2-1,j/2-1);
	double absmix = ATOOLS::sqr(mix.real())+ATOOLS::sqr(mix.imag());
	if (ATOOLS::IsZero(absmix)) continue;
	GZprime += inc = 
	  3.*g1prime*absmix/(24.*M_PI*M2)*
	  ((2.*M2-mq2-ma2)/2.-3.*massq*massa-ATOOLS::sqr(ma2-mq2)/(2.*M2)) *
	  sqrt(ATOOLS::sqr(M2-mq2-ma2)-4.*ma2*mq2)/(2.*MZprime);
	msg_Out()<<"   Add Z' --> "<<quark<<"+"<<anti<<" ("<<i<<"), "
		 <<" add "<<inc<<" GeV.\n";
      }
    }
  }

  Flavour flav;
  flav = Flavour(kf_Z0_2);
  flav.SetMass(ScalarConstant(string("M_Z'")));
  flav.SetHadMass(MZprime);
  flav.SetMassOn(true);
  flav.SetWidth(GZprime);

  msg_Out()<<METHOD<<" initializes Z' boson with \n"
	   <<"    mass = "<<MZprime<<" GeV and width = "<<GZprime<<" GeV\n"
	   <<"    for g'_1 = "<<ScalarConstant(std::string("g'_1"))<<".\n";
}
Exemplo n.º 2
0
void Lund_Interface::AdjustProperties(Flavour flav)
{
  int kc = pycomp(SherpaToIdhep(flav));
  if(kc>500) return;
  // adjust mass
  double pythiamass = pydat2.pmas[1-1][kc-1];
  double sherpamass = flav.HadMass();
  flav.SetMass(pythiamass);
  if( !(abs(sherpamass-pythiamass)/sherpamass < 1.e-2) ) {
    msg_Info()<<METHOD<<" Adjusted mass of "<<flav<<" ("<<flav.Kfcode()
        <<") from "<<sherpamass<<" to "<<pythiamass<<" to allow Pythia decays."<<endl;
  }
}