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. More...

virtual AlgStatus_t	GetStatus (void) const
	Get algorithm status. More...

virtual bool	AllowReconfig (void) const

virtual AlgCmp_t	Compare (const Algorithm *alg) const
	Compare with input algorithm. More...

virtual void	SetId (const AlgId &id)
	Set algorithm ID. More...

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. More...

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. More...

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. More...

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. More...

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 More...

int	AddLowRegistry (Registry *rp, bool owns=true)
	add registry with lowest priority, also update ownership More...

int	MergeTopRegistry (const Registry &r)

int	AddTopRegisties (const vector< Registry * > &rs, bool owns=false)
	Add registries with top priority, also udated Ownerships. More...

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,...) More...

AlgId	fID
	algorithm name and configuration set More...

vector< Registry * >	fConfVect

vector< bool >	fOwnerships
	ownership for every registry in fConfVect More...

AlgStatus_t	fStatus
	algorithm execution status More...

AlgMap *	fOwnedSubAlgMp
	local pool for owned sub-algs (taken out of the factory pool) More...

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 sussex.ac.uk> University of Sussex

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

Created:: July XX, 2020

License:: Copyright (c) 2003-2024, 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

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

private

Definition at line 39 of file DarkSectorDecayer.h.

Constructor & Destructor Documentation

DarkSectorDecayer::DarkSectorDecayer ( )

Definition at line 43 of file DarkSectorDecayer.cxx.

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

DarkSectorDecayer::DarkSectorDecayer ( string config )

Definition at line 49 of file DarkSectorDecayer.cxx.

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

DarkSectorDecayer::~DarkSectorDecayer ( )

virtual

Definition at line 55 of file DarkSectorDecayer.cxx.

 {
 
 }

Member Function Documentation

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.

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

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

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.

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

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

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

protected

Definition at line 216 of file DarkSectorDecayer.cxx.

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().

 {
   // 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;
 }

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

protected

Definition at line 249 of file DarkSectorDecayer.cxx.

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().

 {
   // 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;
 }

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

protected

Definition at line 118 of file DarkSectorDecayer.cxx.

References genie::PDGLibrary::Find(), fPhaseSpaceGenerator, genie::RandomGen::Instance(), genie::PDGLibrary::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().

 {
   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;
 }

void DarkSectorDecayer::LoadConfig ( void )

protectedvirtual

Definition at line 354 of file DarkSectorDecayer.cxx.

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().

 {
 
   // 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 ) ;
   }
 
 }

string DarkSectorDecayer::ParticleGunKineAsString ( const TLorentzVector & vec4 )

staticprivate

Definition at line 326 of file DarkSectorDecayer.cxx.

References genie::constants::kPi.

Referenced by Decay().

 {
   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();
 }

void DarkSectorDecayer::ProcessEventRecord ( GHepRecord * event ) const

virtual

Implements genie::EventRecordVisitorI.

Definition at line 60 of file DarkSectorDecayer.cxx.

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().

 {
   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";
 
 }

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

protected

Definition at line 200 of file DarkSectorDecayer.cxx.

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

Referenced by ProcessEventRecord().

 {
   // 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;
 }

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

protected

Definition at line 277 of file DarkSectorDecayer.cxx.

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

Referenced by ProcessEventRecord().

                                  {
 
   // 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);
   }
 }

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

protected

Definition at line 306 of file DarkSectorDecayer.cxx.

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

Referenced by ProcessEventRecord().

 {
   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;
 }