evgen::ldm::Kaon2HNLFlux Class Reference

Kaon2HNLFlux class definiton. More...

Inheritance diagram for evgen::ldm::Kaon2HNLFlux:

Public Member Functions
	Kaon2HNLFlux (fhicl::ParameterSet const &pset)
	Constructor. More...
	~Kaon2HNLFlux ()
	Destructor. More...
bool	MakeFlux (const simb::MCFlux &flux, MeVPrtlFlux &hnl, double &weight) override
void	configure (const fhicl::ParameterSet &) override
	Interface for configuring the particular algorithm tool. More...
double	MaxWeight () override
Public Member Functions inherited from evgen::ldm::IMeVPrtlFlux
virtual	~IMeVPrtlFlux () noexcept=default
	Virtual Destructor. More...
	IMeVPrtlFlux (const fhicl::ParameterSet &pset)
Public Member Functions inherited from evgen::ldm::IMeVPrtlStage
virtual	~IMeVPrtlStage () noexcept
	Virtual Destructor. More...
	IMeVPrtlStage (const char *name)
TVector3	RandomUnitVector ()
double	GetRandom ()
const char *	Name ()

Private Attributes
double	fM
	Mass of HNL [GeV]. More...
double	fMagUe4
double	fMagUm4
bool	fKDAROnly

Additional Inherited Members
Protected Member Functions inherited from evgen::ldm::IMeVPrtlFlux
TLorentzVector	BeamOrigin ()
double	EnuLab (double enucm, TLorentzVector meson_mom, TLorentzVector meson_pos)
Protected Attributes inherited from evgen::ldm::IMeVPrtlFlux
evgb::EvtTimeShiftI *	fTimeShiftMethod
TRotation	fBeam2Det
TVector3	fBeamOrigin
std::string	fSpillTimeConfig
Protected Attributes inherited from evgen::ldm::IMeVPrtlStage
CLHEP::HepRandomEngine *	fEngine
const char *	fName

Detailed Description

Kaon2HNLFlux class definiton.

Implementation of Kaon->HNL branching ratio taken from: arXiv:1912.07622

Definition at line 45 of file Kaon2HNLFlux_tool.cc.

Constructor & Destructor Documentation

evgen::ldm::Kaon2HNLFlux::Kaon2HNLFlux

(

fhicl::ParameterSet const &

pset

)

Constructor.

Definition at line 71 of file Kaon2HNLFlux_tool.cc.

                                                       :
  IMeVPrtlStage("Kaon2HNLFlux"), 
  IMeVPrtlFlux(pset) 
{
    this->configure(pset);

}

evgen::ldm::Kaon2HNLFlux::~Kaon2HNLFlux

(

)

Destructor.

Definition at line 81 of file Kaon2HNLFlux_tool.cc.

{
}

Member Function Documentation

void evgen::ldm::Kaon2HNLFlux::configure ( const fhicl::ParameterSet &  )

overridevirtual

Interface for configuring the particular algorithm tool.

Parameters

ParameterSet

The input set of parameters for configuration

Implements evgen::ldm::IMeVPrtlStage.

Definition at line 153 of file Kaon2HNLFlux_tool.cc.

{
  fM = pset.get<double>("M");
  fMagUm4 = pset.get<double>("MagUm4");
  fMagUe4 = pset.get<double>("MagUe4");

  fKDAROnly = pset.get<bool>("KDAROnly", false);

  double max_mass = (fMagUe4 > 0.) ? (Constants::Instance().kplus_mass - Constants::Instance().elec_mass) : 
      (Constants::Instance().kplus_mass - Constants::Instance().muon_mass);

  if (fM > max_mass) {
    throw cet::exception("Kaon2HNLFlux Tool: BAD MASS. Configured mass (" + std::to_string(fM) +
         ") is larger than maximum allowed by enabled couplings (" + std::to_string(max_mass) +  ").");
  }

}

bool evgen::ldm::Kaon2HNLFlux::MakeFlux ( const simb::MCFlux &  flux, MeVPrtlFlux &  hnl, double &  weight  )

overridevirtual

Implements evgen::ldm::IMeVPrtlFlux.

Definition at line 177 of file Kaon2HNLFlux_tool.cc.

                                                                                            {
  // make the kaon parent
  evgen::ldm::KaonParent kaon(flux);
  if (abs(kaon.kaon_pdg) != 321) return false; // Only take charged kaons

  // select on the kaon
  if (fKDAROnly && (kaon.mom.P() > 1e-3 || kaon.pos.Z() < 72000.)) return false;
  if (fKDAROnly) std::cout << "FOUND KDAR\n";

  TLorentzVector Beam4 = BeamOrigin();

  // get position in detector frame
  hnl.pos_beamcoord = kaon.pos;
  hnl.pos = kaon.pos;
  hnl.pos.Transform(fBeam2Det);
  hnl.pos += Beam4;

  // Branch the parent Kaon Decay
  double hnl_mass = fM;
  std::pair<double, bool> decay = Branch(hnl_mass, fMagUe4, fMagUm4, GetRandom());
  double br = decay.first;
  bool is_muon = decay.second;
  double lep_mass = is_muon ? Constants::Instance().muon_mass : Constants::Instance().elec_mass;

  std::cout << "BR: " << br << std::endl;

  // ignore if we can't make this hnl
  // Ignore if branching ratio is exactly 0.
  if (br == 0.) return false;

  // get the momentum direction in the kaon parent rest frame
  double p = hnl_momentum(Constants::Instance().kplus_mass, lep_mass, hnl_mass);
  double e = sqrt(p*p + hnl_mass * hnl_mass);
  // Two-body decays are isotropic
  hnl.mom = TLorentzVector(p*RandomUnitVector(), e);

  // boost to lab frame
  TLorentzVector mom = hnl.mom;
  mom.Boost(kaon.mom.BoostVector());

  hnl.mom_beamcoord = mom;
  // rotate to detector frame
  hnl.mom = mom;
  hnl.mom.Transform(fBeam2Det);

  hnl.kmom_beamcoord = kaon.mom;
  // also save the kaon momentum in the detector frame
  hnl.kmom = kaon.mom;
  hnl.kmom.Transform(fBeam2Det);

  // and save the secondary momentum
  hnl.sec = hnl.kmom - hnl.mom;
  hnl.sec_beamcoord = hnl.kmom_beamcoord - hnl.mom_beamcoord;

  // The weight is the importance weight times the branching-ratio weight 
  weight = kaon.weight * br / SMKaonBR(kaon.kaon_pdg);

  // set the mixing
  hnl.C1 = fMagUe4;
  hnl.C2 = fMagUm4;
  hnl.mass = fM;

  hnl.kaon_pdg = kaon.kaon_pdg;
  hnl.secondary_pdg = (is_muon ? 11 : 13) * (kaon.kaon_pdg > 0 ? 1 : -1);
  hnl.generator = 1; // kHNL

  // equivalent neutrino energy
  hnl.equiv_enu = EnuLab(flux.fnecm, hnl.kmom, hnl.pos);

  return true;
}

double evgen::ldm::Kaon2HNLFlux::MaxWeight ( )

overridevirtual

Implements evgen::ldm::IMeVPrtlStage.

Definition at line 171 of file Kaon2HNLFlux_tool.cc.

                               { 
  // Weight comes from the NuMi importance weight -- max is 100 (add in an epsilon)
  // Scale by the branching ratios here
  return 100.0001 * std::max(BranchingRatio(fM, fMagUe4, false) / SMKaonBR(321), BranchingRatio(fM, fMagUm4, true) / SMKaonBR(321));
}

Member Data Documentation

bool evgen::ldm::Kaon2HNLFlux::fKDAROnly

private

Definition at line 68 of file Kaon2HNLFlux_tool.cc.

double evgen::ldm::Kaon2HNLFlux::fM

private

Mass of HNL [GeV].

Definition at line 65 of file Kaon2HNLFlux_tool.cc.

double evgen::ldm::Kaon2HNLFlux::fMagUe4

private

Definition at line 66 of file Kaon2HNLFlux_tool.cc.

double evgen::ldm::Kaon2HNLFlux::fMagUm4

private

Definition at line 67 of file Kaon2HNLFlux_tool.cc.

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The documentation for this class was generated from the following file:

• Kaon2HNLFlux_tool.cc