genie::DarkSectorDecayer Class Reference

Dark Sector decayer module. More...

#include <DarkSectorDecayer.h>

Inheritance diagram for genie::DarkSectorDecayer:

Collaboration diagram for genie::DarkSectorDecayer:

Public Member Functions
	DarkSectorDecayer ()
	DarkSectorDecayer (string config)
virtual	~DarkSectorDecayer ()
virtual void	Configure (const Registry &config)
virtual void	Configure (string config)
void	ProcessEventRecord (GHepRecord *event) const
Public Member Functions inherited from genie::EventRecordVisitorI
virtual	~EventRecordVisitorI ()
Public Member Functions inherited from genie::Algorithm
virtual	~Algorithm ()
virtual void	FindConfig (void)
virtual const Registry &	GetConfig (void) const
Registry *	GetOwnedConfig (void)
virtual const AlgId &	Id (void) const
	Get algorithm ID.
virtual AlgStatus_t	GetStatus (void) const
	Get algorithm status.
virtual bool	AllowReconfig (void) const
virtual AlgCmp_t	Compare (const Algorithm *alg) const
	Compare with input algorithm.
virtual void	SetId (const AlgId &id)
	Set algorithm ID.
virtual void	SetId (string name, string config)
const Algorithm *	SubAlg (const RgKey &registry_key) const
void	AdoptConfig (void)
void	AdoptSubstructure (void)
virtual void	Print (ostream &stream) const
	Print algorithm info.

Protected Member Functions
virtual void	LoadConfig (void)
bool	ToBeDecayed (const GHepParticle &p) const
std::vector< GHepParticle >	Decay (const GHepParticle &mother, const std::vector< int > &pdg_daughters) const
int	SelectDecayChannel (const std::vector< DecayChannel > &dcs, double total_amplitude) const
std::vector< DecayChannel >	DarkMediatorDecayChannels (void) const
std::vector< DecayChannel >	DarkNeutrinoDecayChannels (int mother_pdg) const
void	SetSpaceTime (std::vector< GHepParticle > &pp, const GHepParticle &mother, double total_amplitude) const
Protected Member Functions inherited from genie::EventRecordVisitorI
	EventRecordVisitorI ()
	EventRecordVisitorI (string name)
	EventRecordVisitorI (string name, string config)
Protected Member Functions inherited from genie::Algorithm
	Algorithm ()
	Algorithm (string name)
	Algorithm (string name, string config)
void	Initialize (void)
void	DeleteConfig (void)
void	DeleteSubstructure (void)
Registry *	ExtractLocalConfig (const Registry &in) const
Registry *	ExtractLowerConfig (const Registry &in, const string &alg_key) const
	Split an incoming configuration Registry into a block valid for the sub-algo identified by alg_key.
template<class T>
bool	GetParam (const RgKey &name, T &p, bool is_top_call=true) const
template<class T>
bool	GetParamDef (const RgKey &name, T &p, const T &def) const
template<class T>
int	GetParamVect (const std::string &comm_name, std::vector< T > &v, bool is_top_call=true) const
	Handle to load vectors of parameters.
int	GetParamVectKeys (const std::string &comm_name, std::vector< RgKey > &k, bool is_top_call=true) const
template<class T>
int	GetParamMat (const std::string &comm_name, TMatrixT< T > &mat, bool is_top_call=true) const
	Handle to load matrix of parameters.
template<class T>
int	GetParamMatSym (const std::string &comm_name, TMatrixTSym< T > &mat, bool is_top_call=true) const
int	GetParamMatKeys (const std::string &comm_name, std::vector< RgKey > &k, bool is_top_call=true) const
int	AddTopRegistry (Registry *rp, bool owns=true)
	add registry with top priority, also update ownership
int	AddLowRegistry (Registry *rp, bool owns=true)
	add registry with lowest priority, also update ownership
int	MergeTopRegistry (const Registry &r)
int	AddTopRegisties (const vector< Registry * > &rs, bool owns=false)
	Add registries with top priority, also udated Ownerships.

Private Types
using	DecayChannel = std::pair<std::vector<int>, double>

Static Private Member Functions
static string	ParticleGunKineAsString (const TLorentzVector &vec4)

Private Attributes
TGenPhaseSpace	fPhaseSpaceGenerator
double	fEps2
std::array< double, 4 >	fMixing2s
double	fAlpha_D
double	fDNuMass
double	fDNuMass2
double	fDMediatorMass
double	fDMediatorMass2

Additional Inherited Members
Static Public Member Functions inherited from genie::Algorithm
static string	BuildParamVectKey (const std::string &comm_name, unsigned int i)
static string	BuildParamVectSizeKey (const std::string &comm_name)
static string	BuildParamMatKey (const std::string &comm_name, unsigned int i, unsigned int j)
static string	BuildParamMatRowSizeKey (const std::string &comm_name)
static string	BuildParamMatColSizeKey (const std::string &comm_name)
Protected Attributes inherited from genie::Algorithm
bool	fAllowReconfig
bool	fOwnsSubstruc
	true if it owns its substructure (sub-algs,...)
AlgId	fID
	algorithm name and configuration set
vector< Registry * >	fConfVect
vector< bool >	fOwnerships
	ownership for every registry in fConfVect
AlgStatus_t	fStatus
	algorithm execution status
AlgMap *	fOwnedSubAlgMp
	local pool for owned sub-algs (taken out of the factory pool)

Detailed Description

Dark Sector decayer module.

     A simple decay simulation...
     ....
     Is a concerete implementation of the EventRecordVisitorI interface.

Author

Iker de Icaza <i.de-icaza-astiz \at sussex.ac.uk> University of Sussex

Costas Andreopoulos <c.andreopoulos \at cern.ch> University of Liverpool

Created:\n July XX, 2020

License:\n Copyright (c) 2003-2025, The GENIE Collaboration

For the full text of the license visit http://copyright.genie-mc.org

Definition at line 37 of file DarkSectorDecayer.h.

Member Typedef Documentation

DecayChannel

using genie::DarkSectorDecayer::DecayChannel = std::pair<std::vector<int>, double>

private

Definition at line 39 of file DarkSectorDecayer.h.

Constructor & Destructor Documentation

DarkSectorDecayer() [1/2]

DarkSectorDecayer::DarkSectorDecayer

(

)

Definition at line 43 of file DarkSectorDecayer.cxx.

                                     :
  EventRecordVisitorI("genie::DarkSectorDecayer")
{
 
}

References genie::EventRecordVisitorI::EventRecordVisitorI().

DarkSectorDecayer() [2/2]

DarkSectorDecayer::DarkSectorDecayer

(

string

config

)

Definition at line 49 of file DarkSectorDecayer.cxx.

                                                  :
  EventRecordVisitorI("genie::DarkSectorDecayer", config)
{
 
}

References genie::EventRecordVisitorI::EventRecordVisitorI().

~DarkSectorDecayer()

DarkSectorDecayer::~DarkSectorDecayer ( )

virtual

Definition at line 55 of file DarkSectorDecayer.cxx.

{
 
}

Member Function Documentation

Configure() [1/2]

void DarkSectorDecayer::Configure ( const Registry & config )

virtual

Configure the algorithm with an external registry The registry is merged with the top level registry if it is owned, Otherwise a copy of it is added with the highest priority

Reimplemented from genie::Algorithm.

Definition at line 342 of file DarkSectorDecayer.cxx.

{
  Algorithm::Configure(config);
  this->LoadConfig();
}

References genie::Algorithm::Configure(), and LoadConfig().

Configure() [2/2]

void DarkSectorDecayer::Configure ( string config )

virtual

Configure the algorithm from the AlgoConfigPool based on param_set string given in input An algorithm contains a vector of registries coming from different xml configuration files, which are loaded according a very precise prioriy This methods will load a number registries in order of priority: 1) "Tunable" parameter set from CommonParametes. This is loaded with the highest prioriry and it is designed to be used for tuning procedure Usage not expected from the user. 2) For every string defined in "CommonParame" the corresponding parameter set will be loaded from CommonParameter.xml 3) parameter set specified by the config string and defined in the xml file of the algorithm 4) if config is not "Default" also the Default parameter set from the same xml file will be loaded Effectively this avoids the repetion of a parameter when it is not changed in the requested configuration

Reimplemented from genie::Algorithm.

Definition at line 348 of file DarkSectorDecayer.cxx.

{
  Algorithm::Configure(config);
  this->LoadConfig();
}

References genie::Algorithm::Configure(), and LoadConfig().

DarkMediatorDecayChannels()

std::vector< DarkSectorDecayer::DecayChannel > DarkSectorDecayer::DarkMediatorDecayChannels ( void ) const

protected

Definition at line 216 of file DarkSectorDecayer.cxx.

{
  // eq (4) and (5) and maybe some other higher order variations
 
  static constexpr std::array<int, 3> neutrinos = {kPdgNuE, kPdgNuMu, kPdgNuTau};
  static constexpr std::array<int, 3> antineutrinos = {kPdgAntiNuE, kPdgAntiNuMu, kPdgAntiNuTau};
  std::vector<DarkSectorDecayer::DecayChannel> dcs;
 
  for(size_t i=0; i<neutrinos.size(); ++i){
    for(size_t j=0; j<antineutrinos.size(); ++j){// for antineutrinos
      const double decay_width = fAlpha_D/3. * fMixing2s[i]*fMixing2s[j] * fDMediatorMass;
      dcs.push_back(DecayChannel{{neutrinos[i], antineutrinos[j]}, decay_width});
    }
  }
 
  static const double electron_threshold = 2.*PDGLibrary::Instance()->Find(kPdgElectron)->Mass() ;
  if(fDMediatorMass > electron_threshold ){
    double ratio = electron_threshold / fDMediatorMass ;
    double phase_space_correction = sqrt(1. - ratio*ratio ) ;
    const double decay_width = kAem*fEps2/3. * fDMediatorMass * phase_space_correction ;
    dcs.push_back(DecayChannel{{kPdgElectron, kPdgPositron}, decay_width});
  }
 
  static const double muon_threshold = 2.*PDGLibrary::Instance()->Find(kPdgMuon)->Mass() ;
  if(fDMediatorMass > muon_threshold ){
    double ratio = muon_threshold / fDMediatorMass ;
    double phase_space_correction = sqrt(1. - ratio*ratio ) ;
    const double decay_width = kAem*fEps2/3. * fDMediatorMass * phase_space_correction ;
    dcs.push_back(DecayChannel{{kPdgMuon, kPdgAntiMuon}, decay_width});
  }
  return dcs;
}

References fAlpha_D, fDMediatorMass, fEps2, genie::PDGLibrary::Find(), fMixing2s, genie::PDGLibrary::Instance(), genie::constants::kAem, genie::kPdgAntiMuon, genie::kPdgAntiNuE, genie::kPdgAntiNuMu, genie::kPdgAntiNuTau, genie::kPdgElectron, genie::kPdgMuon, genie::kPdgNuE, genie::kPdgNuMu, genie::kPdgNuTau, and genie::kPdgPositron.

Referenced by ProcessEventRecord().

DarkNeutrinoDecayChannels()

std::vector< DarkSectorDecayer::DecayChannel > DarkSectorDecayer::DarkNeutrinoDecayChannels ( int mother_pdg ) const

protected

Definition at line 249 of file DarkSectorDecayer.cxx.

{
  // eq (3) and higher order variations
 
  static constexpr std::array<int, 3> neutrinos = {kPdgNuE, kPdgNuMu, kPdgNuTau};
  static constexpr std::array<int, 3> antineutrinos = {kPdgAntiNuE, kPdgAntiNuMu, kPdgAntiNuTau};
  std::vector<DarkSectorDecayer::DecayChannel> dcs;
 
  if(fDNuMass > fDMediatorMass){
    for(size_t i=0; i<neutrinos.size(); ++i){
      const double mass2ratio = fDMediatorMass2/fDNuMass2;
      const double p0 = 0.5 * fAlpha_D * fMixing2s[3] * fMixing2s[i];
      const double p1 = fDNuMass*fDNuMass2/fDMediatorMass2;
      const double p2 = 1 - mass2ratio;
      const double p3 = 1 + mass2ratio - 2*mass2ratio*mass2ratio;
      const double decay_width = p0 * p1 * p2 * p3;
 
      if(mother_pdg == kPdgDarkNeutrino){
        dcs.push_back(DecayChannel{{neutrinos[i], kPdgDNuMediator}, decay_width});
      }
      else if(mother_pdg == kPdgAntiDarkNeutrino){
        dcs.push_back(DecayChannel{{antineutrinos[i], kPdgDNuMediator}, decay_width});
      }
    }
  }
  return dcs;
}

References fAlpha_D, fDMediatorMass, fDMediatorMass2, fDNuMass, fDNuMass2, fMixing2s, genie::kPdgAntiDarkNeutrino, genie::kPdgAntiNuE, genie::kPdgAntiNuMu, genie::kPdgAntiNuTau, genie::kPdgDarkNeutrino, genie::kPdgDNuMediator, genie::kPdgNuE, genie::kPdgNuMu, and genie::kPdgNuTau.

Referenced by ProcessEventRecord().

Decay()

std::vector< GHepParticle > DarkSectorDecayer::Decay ( const GHepParticle & mother, const std::vector< int > & pdg_daughters ) const

protected

Definition at line 118 of file DarkSectorDecayer.cxx.

{
  TLorentzVector mother_p4 = *(mother.P4());
  LOG("DarkSectorDecayer", pINFO)
    << "Decaying a " << mother.Name()
    << " with P4 = " << utils::print::P4AsString(&mother_p4);
 
  unsigned int nd = pdg_daughters.size();
  std::vector<double> mass(nd, 0.);
 
  for(unsigned int iparticle = 0; iparticle < nd; iparticle++) {
    TParticlePDG * daughter = PDGLibrary::Instance()->Find(pdg_daughters[iparticle]);
    assert(daughter);
 
    mass[iparticle] = daughter->Mass();
 
    SLOG("DarkSectorDecayer", pINFO)
      << "+ daughter[" << iparticle << "]: "
      << daughter->GetName() << " (pdg-code = "
      << pdg_daughters[iparticle] << ", mass = " << mass[iparticle] << ")";
  }
 
  bool is_permitted = fPhaseSpaceGenerator.SetDecay( mother_p4, nd, mass.data() );
  assert(is_permitted);
 
  // Find the maximum phase space decay weight
  double wmax = -1;
  for(int i=0; i<50; i++) {
    double w = fPhaseSpaceGenerator.Generate();
    wmax = TMath::Max(wmax,w);
  }
  assert(wmax>0);
  LOG("DarkSectorDecayer", pINFO)
    << "Max phase space gen. weight for current decay: " << wmax;
 
  // Generating un-weighted decays
  RandomGen * rnd = RandomGen::Instance();
  wmax *= 2;
  bool accept_decay=false;
  unsigned int itry=0;
 
  while(!accept_decay){
    itry++;
    assert(itry<kMaxUnweightDecayIterations);
 
    double w  = fPhaseSpaceGenerator.Generate();
    double gw = wmax * rnd->RndDec().Rndm();
 
    if(w>wmax) {
      LOG("DarkSectorDecayer", pWARN)
        << "Current decay weight = " << w << " > wmax = " << wmax;
    }
    LOG("DarkSectorDecayer", pINFO)
      << "Current decay weight = " << w << " / R = " << gw;
 
    accept_decay = (gw<=w);
  }
 
  // A decay was generated - Copy to the event record
  std::vector<GHepParticle> particles;
  // Loop over daughter list and add corresponding GHepParticles
  for(unsigned int id = 0; id < nd; id++) {
    const TLorentzVector * daughter_p4 = fPhaseSpaceGenerator.GetDecay(id);
    SLOG("DarkSectorDecayer", pINFO)
      << "Adding daughter particle with PDG code = " << pdg_daughters[id]
      << " with P4 = " << utils::print::P4AsShortString( daughter_p4 );
    SLOG("DarkSectorDecayer", pDEBUG)
      << "Particle Gun Kinematics: "
      << "PDG : " << pdg_daughters[id] << ", "
      << DarkSectorDecayer::ParticleGunKineAsString( *daughter_p4 );
    GHepStatus_t daughter_status_code = (pdg_daughters[id]==kPdgDNuMediator)
      ? kIStDecayedState : kIStStableFinalState;
    particles.push_back(GHepParticle(pdg_daughters[id], daughter_status_code,
                                     -1, -1, -1, -1,
                                     *daughter_p4, TLorentzVector()));
  }
 
  return particles;
}

References genie::PDGLibrary::Find(), fPhaseSpaceGenerator, genie::PDGLibrary::Instance(), genie::RandomGen::Instance(), genie::kIStDecayedState, genie::kIStStableFinalState, genie::controls::kMaxUnweightDecayIterations, genie::kPdgDNuMediator, LOG, genie::GHepParticle::Name(), genie::GHepParticle::P4(), genie::utils::print::P4AsShortString(), genie::utils::print::P4AsString(), ParticleGunKineAsString(), pDEBUG, pINFO, pWARN, genie::RandomGen::RndDec(), and SLOG.

Referenced by ProcessEventRecord().

LoadConfig()

void DarkSectorDecayer::LoadConfig ( void )

protectedvirtual

Definition at line 354 of file DarkSectorDecayer.cxx.

{
 
  // Check particles are in the PDG library, quit if they don't exist
  constexpr std::array<int, 3> pdgc_mothers = {kPdgDNuMediator,
                                               kPdgDarkNeutrino,
                                               kPdgAntiDarkNeutrino};
  for (auto & pdg_code : pdgc_mothers){
    TParticlePDG * mother = PDGLibrary::Instance()->Find(pdg_code);
    if(!mother) {
      LOG("DarkSectorDecayer", pERROR)
        << "\n *** The particle with PDG code = " << pdg_code
        << " was not found in PDGLibrary";
      exit(78);
    }
  }
 
  bool good_configuration = true ;
 
  double DKineticMixing = 0.;    // \varepsilon
  this->GetParam("Dark-KineticMixing", DKineticMixing);
  fEps2 = DKineticMixing * DKineticMixing;
 
  bool force_unitarity = false ;
  GetParam("Dark-Mixing-ForceUnitarity", force_unitarity ) ;
 
  unsigned int n_min_mixing = force_unitarity ? 3 : 4 ;
 
  std::vector<double> DMixing2s;  // |U_{\alpha 4}|^2
  this->GetParamVect("Dark-Mixings2", DMixing2s);
 
  // check whether we have enough mixing elements
  if ( DMixing2s.size () < n_min_mixing ) {
 
    good_configuration = false ;
    LOG("DarkSectorDecayer", pERROR )
      << "Not enough mixing elements specified, only specified "
      << DMixing2s.size() << " / " << n_min_mixing ;
  }
 
  double tot_mix = 0. ;
  for( unsigned int i = 0; i < n_min_mixing ; ++i ) {
    if ( DMixing2s[i] < 0. ) {
      good_configuration = false ;
      LOG("DarkSectorDecayer", pERROR )
        << "Mixing " << i << " non positive: " << DMixing2s[i] ;
      continue ;
    }
    tot_mix += fMixing2s[i] = DMixing2s[i] ;
  }
 
  if ( force_unitarity ) {
    fMixing2s[3] = 1. - tot_mix ;
  }
 
  this->GetParam("Dark-Alpha", fAlpha_D);
 
  fDNuMass = 0.;
  this->GetParam("Dark-NeutrinoMass", fDNuMass);
  fDNuMass2 = fDNuMass * fDNuMass;
 
  fDMediatorMass = 0.;
  this->GetParam("Dark-MediatorMass", fDMediatorMass);
  fDMediatorMass2 = fDMediatorMass * fDMediatorMass;
 
  // The model is build on the assumption that the mass of the
  // mediator is smaller than the mass of the dark neutrino. For the
  // cross section, this is not a problem.
  // The decayer though is sensitive to this as the only known decay
  // amplitude of the dark neutrino requires the mediator in the final
  // state.
  // Until the decay amplitude in neutrino is not available
  // we need to check that the mass hierarchy is respected.
  if ( fDMediatorMass >= fDNuMass ) {
    good_configuration = false ;
    LOG("DarkSectorDecayer", pERROR )
      << "Dark mediator mass (" <<  fDMediatorMass
      << " GeV) too heavy for the dark neutrino ("
      << fDNuMass << " GeV) to decay" ;
  }
 
  // The other check we need is that the mass of the mediator
  // has to be smaller than twice the pion mass
  // Because again in that case we would not be able to
  // have a proper decay rate since the Mediator would decay in
  // pion but since we don't have the decay amplitude the
  // decay rate would be wrong
  double pion_threshold = PDGLibrary::Instance()->Find( kPdgPiP )->Mass() ;
  if ( fDMediatorMass >= pion_threshold ) {
    good_configuration = false ;
    LOG("DarkSectorDecayer", pERROR )
      << "Dark mediator mass (" <<  fDMediatorMass
      << " GeV) too heavy with respect to the pion decay threshold ("
      << pion_threshold << " GeV)" ;
  }
 
  if ( ! good_configuration ) {
    LOG("DarkSectorDecayer", pFATAL ) << "Wrong configuration. Exiting" ;
    exit ( 78 ) ;
  }
 
}

References fAlpha_D, fDMediatorMass, fDMediatorMass2, fDNuMass, fDNuMass2, fEps2, genie::PDGLibrary::Find(), fMixing2s, genie::Algorithm::GetParam(), genie::Algorithm::GetParamVect(), genie::PDGLibrary::Instance(), genie::kPdgAntiDarkNeutrino, genie::kPdgDarkNeutrino, genie::kPdgDNuMediator, genie::kPdgPiP, LOG, pERROR, and pFATAL.

Referenced by Configure(), and Configure().

ParticleGunKineAsString()

string DarkSectorDecayer::ParticleGunKineAsString ( const TLorentzVector & vec4 )

staticprivate

Definition at line 326 of file DarkSectorDecayer.cxx.

{
  std::ostringstream fmt;
 
  double P0 = vec4.Vect().Mag();
  double thetaYZ = TMath::ASin(vec4.Py()/P0);
  double thetaXZ = TMath::ASin(vec4.Px()/(P0 * TMath::Cos(thetaYZ)));
  double rad_to_degrees = 180./kPi;
 
  fmt << "P0 = "  << P0
      << ", ThetaXZ = " << thetaXZ*rad_to_degrees
      << ", ThetaYZ = " << thetaYZ*rad_to_degrees;
 
  return fmt.str();
}

References genie::constants::kPi.

Referenced by Decay().

ProcessEventRecord()

void DarkSectorDecayer::ProcessEventRecord ( GHepRecord * event ) const

virtual

Implements genie::EventRecordVisitorI.

Definition at line 60 of file DarkSectorDecayer.cxx.

{
  LOG("DarkSectorDecayer", pINFO)
    << "Running dark sector decayer ";
 
  // Loop over particles, find unstable ones and decay them
  TObjArrayIter piter(event);
  GHepParticle * p = 0;
  int ipos = -1;
 
  while( (p = (GHepParticle *) piter.Next()) ) {
    ipos++;
    LOG("DarkSectorDecayer", pDEBUG) << "Checking: " << p->Name();
 
    if(!this->ToBeDecayed(*p)) continue;
 
    GHepParticle&  mother = *p; // rename p now we know it will decay
    std::vector<DarkSectorDecayer::DecayChannel> dcs;
    int pdg_code = mother.Pdg();
    if(pdg_code == kPdgDNuMediator){
      dcs = DarkMediatorDecayChannels();
    }
    else if(pdg_code == kPdgDarkNeutrino ||
            pdg_code == kPdgAntiDarkNeutrino){
      dcs = DarkNeutrinoDecayChannels(pdg_code);
    }
 
    for ( const auto & dc : dcs ) {
      std::stringstream amplitudes_msg;
      amplitudes_msg << "Decay amplitude: " << dc.second << " GeV "
                     << " -> " << 1. / dc.second / units::second << "s for channel [" ;
      for ( const auto & pdgc : dc.first ) {
        amplitudes_msg << pdgc << "  " ;
      }
      amplitudes_msg << "]";
      LOG("DarkSectorDecayer", pDEBUG) << amplitudes_msg.str();
    }
 
    double total_amplitude = std::accumulate(dcs.begin(), dcs.end(), 0.,
                                             [](double total,
                                                const DarkSectorDecayer::DecayChannel& dc)
                                             {return total + dc.second;});
 
    int dcid = SelectDecayChannel(dcs, total_amplitude);
    std::vector<GHepParticle> daughters = Decay(mother, dcs[dcid].first);
    SetSpaceTime(daughters, mother, total_amplitude);
 
    for(auto & daughter: daughters){
      daughter.SetFirstMother(ipos);
      event->AddParticle(daughter);
    }
  }
 
  LOG("DarkSectorDecayer", pNOTICE)
    << "Done finding & decaying dark sector particles";
 
}

References DarkMediatorDecayChannels(), DarkNeutrinoDecayChannels(), Decay(), genie::kPdgAntiDarkNeutrino, genie::kPdgDarkNeutrino, genie::kPdgDNuMediator, LOG, genie::GHepParticle::Name(), pDEBUG, genie::GHepParticle::Pdg(), pINFO, pNOTICE, genie::units::second, SelectDecayChannel(), SetSpaceTime(), and ToBeDecayed().

SelectDecayChannel()

int DarkSectorDecayer::SelectDecayChannel ( const std::vector< DecayChannel > & dcs, double total_amplitude ) const

protected

Definition at line 200 of file DarkSectorDecayer.cxx.

{
  // Select a decay based on the amplitudes
  unsigned int ich = 0, sel_ich; // id of selected decay channel
  RandomGen * rnd = RandomGen::Instance();
  double x = total_amplitude * rnd->RndDec().Rndm();
  double partial_sum = 0. ;
  do {
    sel_ich = ich;
    partial_sum += dcs.at(ich++).second;
  } while (x > partial_sum );
  return sel_ich;
}

References genie::RandomGen::Instance(), and genie::RandomGen::RndDec().

Referenced by ProcessEventRecord().

SetSpaceTime()

void DarkSectorDecayer::SetSpaceTime ( std::vector< GHepParticle > & pp, const GHepParticle & mother, double total_amplitude ) const

protected

Definition at line 277 of file DarkSectorDecayer.cxx.

                                 {
 
  // convert decay amplitude into time
  const double lifetime =  1e24/units::second/total_amplitude; // units of 10ˆ-24 s
 
  RandomGen * rnd = RandomGen::Instance();
  double t = rnd->RndDec().Exp(lifetime);
 
  // t is the decay time in the mother reference frame
  // it needs to be boosted by a factor gamma
  t *= mother.P4() -> Gamma() ;
 
  // get beta of decaying particle
  const TLorentzVector & mother_X4 = *(mother.X4());
  TVector3 mother_boost = mother.P4()->BoostVector();
 
  // transport decay_particle with respect to their mother
  constexpr double speed_of_light = units::second/units::meter; // this gives us the speed of light in m/s
  TVector3 daughter_position = mother_X4.Vect() + mother_boost * (speed_of_light * t * 1e-9);// in fm
  TLorentzVector daughter_X4 = TLorentzVector(daughter_position, (mother_X4.T() + t));
 
  for(auto & p : pp){
    p.SetPosition(daughter_X4);
  }
}

References e, genie::RandomGen::Instance(), genie::units::meter, genie::GHepParticle::P4(), genie::RandomGen::RndDec(), genie::units::second, and genie::GHepParticle::X4().

Referenced by ProcessEventRecord().

ToBeDecayed()

bool DarkSectorDecayer::ToBeDecayed ( const GHepParticle & p ) const

protected

Definition at line 306 of file DarkSectorDecayer.cxx.

{
  GHepStatus_t status_code = p.Status();
  if(status_code != kIStDecayedState) return false;
 
  int pdg_code = p.Pdg();
  bool is_handled = false;
  if(pdg_code == kPdgDNuMediator ||
     pdg_code == kPdgDarkNeutrino ||
     pdg_code == kPdgAntiDarkNeutrino){
    is_handled = true;
  }
 
  LOG("DarkSectorDecayer", pDEBUG)
      << "Can decay particle with PDG code = " << pdg_code
      << "? " << ((is_handled)? "Yes" : "No");
 
  return is_handled;
}

References genie::kIStDecayedState, genie::kPdgAntiDarkNeutrino, genie::kPdgDarkNeutrino, genie::kPdgDNuMediator, LOG, pDEBUG, genie::GHepParticle::Pdg(), and genie::GHepParticle::Status().

Referenced by ProcessEventRecord().

Member Data Documentation

fAlpha_D

double genie::DarkSectorDecayer::fAlpha_D

private

Definition at line 78 of file DarkSectorDecayer.h.

Referenced by DarkMediatorDecayChannels(), DarkNeutrinoDecayChannels(), and LoadConfig().

fDMediatorMass

double genie::DarkSectorDecayer::fDMediatorMass

private

Definition at line 81 of file DarkSectorDecayer.h.

Referenced by DarkMediatorDecayChannels(), DarkNeutrinoDecayChannels(), and LoadConfig().

fDMediatorMass2

double genie::DarkSectorDecayer::fDMediatorMass2

private

Definition at line 81 of file DarkSectorDecayer.h.

Referenced by DarkNeutrinoDecayChannels(), and LoadConfig().

fDNuMass

double genie::DarkSectorDecayer::fDNuMass

private

Definition at line 80 of file DarkSectorDecayer.h.

Referenced by DarkNeutrinoDecayChannels(), and LoadConfig().

fDNuMass2

double genie::DarkSectorDecayer::fDNuMass2

private

Definition at line 80 of file DarkSectorDecayer.h.

Referenced by DarkNeutrinoDecayChannels(), and LoadConfig().

fEps2

double genie::DarkSectorDecayer::fEps2

private

Definition at line 76 of file DarkSectorDecayer.h.

Referenced by DarkMediatorDecayChannels(), and LoadConfig().

fMixing2s

std::array<double, 4> genie::DarkSectorDecayer::fMixing2s

private

Definition at line 77 of file DarkSectorDecayer.h.

Referenced by DarkMediatorDecayChannels(), DarkNeutrinoDecayChannels(), and LoadConfig().

fPhaseSpaceGenerator

TGenPhaseSpace genie::DarkSectorDecayer::fPhaseSpaceGenerator

mutableprivate

Definition at line 74 of file DarkSectorDecayer.h.

Referenced by Decay().

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

• DarkSectorDecayer.h
• DarkSectorDecayer.cxx