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genie::BaryonResonanceDecayer Class Reference

Baryon resonance decayer module. More...

#include <BaryonResonanceDecayer.h>

Inheritance diagram for genie::BaryonResonanceDecayer:
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Collaboration diagram for genie::BaryonResonanceDecayer:
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Public Member Functions

 BaryonResonanceDecayer ()
 
 BaryonResonanceDecayer (string config)
 
virtual ~BaryonResonanceDecayer ()
 
void ProcessEventRecord (GHepRecord *event) const
 
virtual void LoadConfig (void)
 

Private Member Functions

void Initialize (void) const
 
bool IsHandled (int pdgc) const
 
void InhibitDecay (int pdgc, TDecayChannel *ch=0) const
 
void UnInhibitDecay (int pdgc, TDecayChannel *ch=0) const
 
double Weight (void) const
 
bool Decay (int dec_part_id, GHepRecord *event) const
 
TDecayChannel * SelectDecayChannel (int dec_part_id, GHepRecord *event, bool &to_be_deleted) const
 
bool DecayExclusive (int dec_part_id, GHepRecord *event, TDecayChannel *ch) const
 
TObjArray * EvolveDeltaBR (int dec_part_pdgc, TObjArray *decay_list, double W) const
 
double EvolveDeltaDecayWidth (int dec_part_pdgc, TDecayChannel *ch, double W) const
 
bool AcceptPionDecay (TLorentzVector lab_pion, int dec_part_id, const GHepRecord *event) const
 
double FinalStateMass (TDecayChannel *ch) const
 
bool IsPiNDecayChannel (TDecayChannel *ch) const
 
double FindDistributionExtrema (unsigned int i, bool find_maximum=false) const
 

Static Private Member Functions

static bool IsDelta (int dec_part_pdgc)
 
static bool HasEvolvedBRs (int dec_part_pdgc)
 
static double PionAngularDist (const double *x, const double *par)
 
static double MinusPionAngularDist (const double *x, const double *par)
 

Private Attributes

TGenPhaseSpace fPhaseSpaceGenerator
 
double fWeight
 
bool fDeltaThetaOnly
 
double fMaxTolerance
 
std::vector< double > fR33
 
std::vector< double > fR31
 
std::vector< double > fR3m1
 
std::vector< double * > fRParams
 
std::vector< double > fQ2Thresholds
 
std::vector< double > fW_max
 
double fFFScaling
 

Additional Inherited Members

- Protected Member Functions inherited from genie::Decayer
 Decayer ()
 
 Decayer (string name)
 
 Decayer (string name, string config)
 
virtual bool ToBeDecayed (int pdgc, GHepStatus_t ist) const
 
virtual bool IsUnstable (int pdgc) const
 
virtual ~Decayer ()
 
void Configure (const Registry &config)
 
void Configure (string config)
 
- Protected Member Functions inherited from genie::EventRecordVisitorI
 EventRecordVisitorI ()
 
 EventRecordVisitorI (string name)
 
 EventRecordVisitorI (string name, string config)
 
virtual ~EventRecordVisitorI ()
 
- 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)
 
RegistryExtractLocalConfig (const Registry &in) const
 
RegistryExtractLowerConfig (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...
 
virtual ~Algorithm ()
 
virtual void FindConfig (void)
 
virtual const RegistryGetConfig (void) const
 
RegistryGetOwnedConfig (void)
 
virtual const AlgIdId (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 AlgorithmSubAlg (const RgKey &registry_key) const
 
void AdoptConfig (void)
 
void AdoptSubstructure (void)
 
virtual void Print (ostream &stream) const
 Print algorithm info. More...
 
- Static Protected 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::Decayer
bool fGenerateWeighted
 generate weighted or unweighted decays? More...
 
bool fRunBefHadroTransp
 is invoked before or after FSI? More...
 
PDGCodeList fParticlesToDecay
 list of particles to be decayed More...
 
PDGCodeList fParticlesNotToDecay
 list of particles for which decay is inhibited More...
 
- 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...
 
AlgMapfOwnedSubAlgMp
 local pool for owned sub-algs (taken out of the factory pool) More...
 

Detailed Description

Baryon resonance decayer module.

      A simple resonance decay simulation built using resonance branching
      fraction data and an N-body phase space generator.
      Since the resonance can be produced off-the-mass-shell, decay
      channels with total-mass > W are suppressed.

      Is a concerete implementation of the EventRecordVisitorI interface.
Author
Costas Andreopoulos <c.andreopoulos cern.ch> University of Liverpool
Created:
November 27, 2004
License:
Copyright (c) 2003-2024, The GENIE Collaboration For the full text of the license visit http://copyright.genie-mc.org

Definition at line 36 of file BaryonResonanceDecayer.h.

Constructor & Destructor Documentation

BaryonResonanceDecayer::BaryonResonanceDecayer ( )

Definition at line 41 of file BaryonResonanceDecayer.cxx.

References Initialize().

41  :
42 Decayer("genie::BaryonResonanceDecayer")
43 {
44  this->Initialize();
45 }
BaryonResonanceDecayer::BaryonResonanceDecayer ( string  config)

Definition at line 47 of file BaryonResonanceDecayer.cxx.

References Initialize().

47  :
48 Decayer("genie::BaryonResonanceDecayer", config)
49 {
50  this->Initialize();
51 }
BaryonResonanceDecayer::~BaryonResonanceDecayer ( )
virtual

Definition at line 53 of file BaryonResonanceDecayer.cxx.

References fRParams.

54 {
55 
56  for ( unsigned int i = 0; i < fRParams.size() ; ++i ) {
57  delete fRParams[i] ;
58  }
59 
60 }
std::vector< double * > fRParams

Member Function Documentation

bool BaryonResonanceDecayer::AcceptPionDecay ( TLorentzVector  lab_pion,
int  dec_part_id,
const GHepRecord event 
) const
private

Definition at line 594 of file BaryonResonanceDecayer.cxx.

References fDeltaThetaOnly, FindDistributionExtrema(), fQ2Thresholds, fR33, fRParams, genie::Kinematics::FSLeptonP4(), fW_max, genie::RandomGen::Instance(), genie::Interaction::KinePtr(), genie::GHepParticle::P4(), PionAngularDist(), and genie::utils::kinematics::Q2().

Referenced by DecayExclusive().

596  {
597 
598  // This evaluate the function W(theta, phi) as a function of the emitted pion and of the status of
599  // the Delta to be decayed and the whole event
600 
601  // in its simplest form W(theta) is
602  // W(Theta) = 1 − P[ 3/2 ] x L_2(cos Theta) + P[ 1/2 ] x L_2(cos Theta)
603  // where
604  // L_2 is the second Legendre polynomial L_2(x) = (3x^2 -1)/2
605  // and P[3/2] and P[1/2] have to some up to 1.
606  // But the code has been extended to include a phi dependence
607 
608  // Get the delta 4-momentum
609  GHepParticle * decay_particle = event->Particle( dec_part_id );
610  TLorentzVector delta_p4 = *(decay_particle->P4() );
611 
612  // find incoming lepton
613  TLorentzVector in_lep_p4( * (event -> Probe()-> GetP4()) ) ;
614 
615  // find outgoing lepton
616  Interaction * interaction = event->Summary();
617  TLorentzVector out_lep_p4 = interaction->KinePtr()->FSLeptonP4() ;
618 
619  TLorentzVector q = in_lep_p4 - out_lep_p4 ;
620 
621  pion.Boost(-delta_p4.BoostVector() ); // this gives us the pion in the Delta reference frame
622  q.Boost(-delta_p4.BoostVector() ); // this gives us the transferred momentm in the Delta reference frame
623 
624  TVector3 pion_dir = pion.Vect().Unit() ;
625  TVector3 z_axis = q.Vect().Unit() ;
626 
627 
628 
629  unsigned int q2_index = 0 ;
630 
631  // find out Q2 region for values
632  // note that Q2 is a lorentz invariant so it does not matter it is evaluated in the lab frame
633  // like in this case or in the Delta reference frame
634  double Q2 = - q.Mag2() ;
635  while( q2_index < fQ2Thresholds.size() ) {
636  if ( Q2 < fQ2Thresholds[q2_index] ) ++q2_index ;
637  else break ;
638  }
639 
640  double w_function ;
641 
642  if ( fDeltaThetaOnly ) {
643 
644  double c_t = pion_dir*z_axis; // cos theta
645 
646  w_function = 1. - (fR33[q2_index] - 0.5)*(3.*c_t*c_t - 1.) ;
647 
648  }
649 
650  else {
651 
652  double x[2] ; // 0 : theta, 1 : phi
653 
654  x[0] = pion_dir.Angle( z_axis ) ; // theta
655 
656  in_lep_p4.Boost(-delta_p4.BoostVector() ) ;
657  out_lep_p4.Boost( -delta_p4.BoostVector() ) ;
658 
659  // evaluate reference frame -> define x axis
660  TVector3 y_axis = in_lep_p4.Vect().Cross( out_lep_p4.Vect() ).Unit() ;
661  TVector3 x_axis = y_axis.Cross(z_axis);
662 
663  TVector3 pion_perp( z_axis.Cross( pion_dir.Cross( z_axis ).Unit() ) ) ;
664 
665  x[1] = pion_perp.Angle( x_axis ) ; // phi
666 
667  w_function = BaryonResonanceDecayer::PionAngularDist( x, fRParams[q2_index] ) ;
668 
669  }
670 
671  if ( fW_max[q2_index] <= 0. ) {
672  const_cast<genie::BaryonResonanceDecayer*>( this ) -> fW_max[q2_index] = FindDistributionExtrema( q2_index, true ) ;
673  }
674 
675  double aidrnd = fW_max[q2_index] * RandomGen::Instance()-> RndDec().Rndm();
676 
677  return ( aidrnd <= w_function ) ;
678 
679 }
Baryon resonance decayer module.
std::vector< double * > fRParams
double Q2(const Interaction *const i)
Definition: KineUtils.cxx:1077
static RandomGen * Instance()
Access instance.
Definition: RandomGen.cxx:71
const TLorentzVector * P4(void) const
Definition: GHepParticle.h:78
Kinematics * KinePtr(void) const
Definition: Interaction.h:76
Summary information for an interaction.
Definition: Interaction.h:56
double FindDistributionExtrema(unsigned int i, bool find_maximum=false) const
const TLorentzVector & FSLeptonP4(void) const
Definition: Kinematics.h:65
static double PionAngularDist(const double *x, const double *par)
STDHEP-like event record entry that can fit a particle or a nucleus.
Definition: GHepParticle.h:39
bool BaryonResonanceDecayer::Decay ( int  dec_part_id,
GHepRecord event 
) const
private

Definition at line 110 of file BaryonResonanceDecayer.cxx.

References DecayExclusive(), fWeight, genie::kIStDecayedState, LOG, pERROR, SelectDecayChannel(), and genie::GHepParticle::SetStatus().

Referenced by ProcessEventRecord().

112 {
113  // Reset previous decay weight
114  fWeight = 1.;
115 
116  // Get particle to be decayed
117  GHepParticle * decay_particle = event->Particle(decay_particle_id);
118  if( ! decay_particle) {
119  LOG("ResonanceDecay", pERROR)
120  << "Particle to be decayed not in the event record. Particle ud: " << decay_particle_id ;
121  return false;
122  }
123 
124  bool to_be_deleted ;
125 
126  // Select a decay channel
127  TDecayChannel * selected_decay_channel =
128  this->SelectDecayChannel(decay_particle_id, event, to_be_deleted ) ;
129 
130  if(!selected_decay_channel) {
131  LOG("ResonanceDecay", pERROR)
132  << "No decay channel for particle " << decay_particle_id ;
133  LOG("ResonanceDecay", pERROR)
134  << *event ;
135 
136  return false;
137  }
138 
139  // Decay the exclusive state and copy daughters in the event record
140  bool decayed = this->DecayExclusive(decay_particle_id, event, selected_decay_channel);
141 
142  if ( to_be_deleted )
143  delete selected_decay_channel ;
144 
145  if ( ! decayed ) return false ;
146 
147  // Update the event weight for each weighted particle decay
148  double weight = event->Weight() * fWeight;
149  event->SetWeight(weight);
150 
151  // Mark input particle as a 'decayed state' & add its daughter links
152  decay_particle->SetStatus(kIStDecayedState);
153 
154  return true;
155 }
#define pERROR
Definition: Messenger.h:59
bool DecayExclusive(int dec_part_id, GHepRecord *event, TDecayChannel *ch) const
TDecayChannel * SelectDecayChannel(int dec_part_id, GHepRecord *event, bool &to_be_deleted) const
#define LOG(stream, priority)
A macro that returns the requested log4cpp::Category appending a string (using the FILE...
Definition: Messenger.h:96
void SetStatus(GHepStatus_t s)
Definition: GHepParticle.h:126
STDHEP-like event record entry that can fit a particle or a nucleus.
Definition: GHepParticle.h:39
bool BaryonResonanceDecayer::DecayExclusive ( int  dec_part_id,
GHepRecord event,
TDecayChannel *  ch 
) const
private

Definition at line 270 of file BaryonResonanceDecayer.cxx.

References AcceptPionDecay(), genie::Decayer::fGenerateWeighted, genie::PDGLibrary::Find(), fPhaseSpaceGenerator, genie::Decayer::fRunBefHadroTransp, fWeight, genie::RandomGen::Instance(), genie::PDGLibrary::Instance(), genie::pdg::IsHadron(), IsPiNDecayChannel(), genie::pdg::IsPion(), genie::kIStHadronInTheNucleus, genie::kIStStableFinalState, genie::controls::kMaxUnweightDecayIterations, genie::kPdgP33m1232_Delta0, genie::kPdgP33m1232_DeltaP, genie::kPdgP33m1232_DeltaPP, LOG, genie::GHepParticle::P4(), pDEBUG, genie::GHepParticle::Pdg(), pINFO, pWARN, genie::RandomGen::RndDec(), SLOG, and genie::GHepParticle::X4().

Referenced by Decay().

272 {
273  // Find the particle to be decayed in the event record
274  GHepParticle * decay_particle = event->Particle(decay_particle_id);
275  if(!decay_particle) return false ;
276 
277  // Get the decayed particle 4-momentum, 4-position and PDG code
278  TLorentzVector decay_particle_p4 = *(decay_particle->P4());
279  TLorentzVector decay_particle_x4 = *(decay_particle->X4());
280  int decay_particle_pdg_code = decay_particle->Pdg();
281 
282  // Get the final state mass spectrum and the particle codes
283  // for the selected decay channel
284  unsigned int nd = ch->NDaughters();
285 
286  int pdgc[nd];
287  double mass[nd];
288 
289  for(unsigned int iparticle = 0; iparticle < nd; iparticle++) {
290 
291  int daughter_code = ch->DaughterPdgCode(iparticle);
292  TParticlePDG * daughter = PDGLibrary::Instance()->Find(daughter_code);
293  assert(daughter);
294 
295  pdgc[iparticle] = daughter_code;
296  mass[iparticle] = daughter->Mass();
297 
298  SLOG("ResonanceDecay", pINFO)
299  << "+ daughter[" << iparticle << "]: "
300  << daughter->GetName() << " (pdg-code = "
301  << pdgc[iparticle] << ", mass = " << mass[iparticle] << ")";
302  }
303 
304  // Check whether the expected channel is Delta->pion+nucleon
305  bool is_delta = (decay_particle_pdg_code == kPdgP33m1232_DeltaPP ||
306  decay_particle_pdg_code == kPdgP33m1232_DeltaP ||
307  decay_particle_pdg_code == kPdgP33m1232_Delta0);
308 
309  bool is_delta_N_Pi_decay = is_delta && this->IsPiNDecayChannel(ch);
310 
311  // Decay the resonance using an N-body phase space generator
312  // The particle will be decayed in its rest frame and then the daughters
313  // will be boosted back to the original frame.
314 
315  bool is_permitted = fPhaseSpaceGenerator.SetDecay(decay_particle_p4, nd, mass);
316  if ( ! is_permitted ) return false ;
317 
318  // Find the maximum phase space decay weight
319  // double wmax = fPhaseSpaceGenerator.GetWtMax();
320  double wmax = -1;
321  for(int i=0; i<50; i++) {
322  double w = fPhaseSpaceGenerator.Generate();
323  wmax = TMath::Max(wmax,w);
324  }
325  assert(wmax>0);
326  LOG("ResonanceDecay", pINFO)
327  << "Max phase space gen. weight for current decay: " << wmax;
328 
330  {
331  // Generating weighted decays
332  // Do a single draw of momentum 4-vectors and then stop,
333  // taking into account the weight for this particular draw
334  double w = fPhaseSpaceGenerator.Generate();
335  fWeight *= TMath::Max(w/wmax, 1.);
336  }
337  else
338  {
339  // Generating un-weighted decays
340  RandomGen * rnd = RandomGen::Instance();
341  wmax *= 2;
342  bool accept_decay=false;
343  unsigned int itry=0;
344 
345  while(!accept_decay)
346  {
347  itry++;
348  assert(itry<kMaxUnweightDecayIterations);
349 
350  double w = fPhaseSpaceGenerator.Generate();
351  double gw = wmax * rnd->RndDec().Rndm();
352 
353  if(w>wmax) {
354  LOG("ResonanceDecay", pWARN)
355  << "Current decay weight = " << w << " > wmax = " << wmax;
356  }
357  LOG("ResonanceDecay", pINFO)
358  << "Current decay weight = " << w << " / R = " << gw;
359 
360  accept_decay = (gw<=w);
361 
362  // Extra logic that applies only for Delta -> N + pi
363  if( accept_decay && is_delta_N_Pi_decay ) {
364 
365  // We don't want the decay Delta -> Pi + N to be isotropic in the Delta referemce frame
366  // as generated by the simple phase space generator.
367  // In order to sample pion distribution according to W(Theta, phi) in the Delta resonance decay,
368  // we make use of the following.
369  // Note that Theta and Phi are defined in a reference frame which depends on the whole event
370  // For each event generated from a Delta -> N + Pi event with Pi emitted at
371  // at angles Theta and Phi (in the Delta rest frame), attach a random number to it.
372  // then we calculate W(Theta, Phi).
373  // Each possible final state is used to evaluate (Theta, Phi),
374  // then a random number is thrown, if the the random number is higher than W(Theta, Phi) drop this event and go
375  // back to re-generate an event and repeat the procedure.
376  // Otherwise keep this event to the record.
377  // For efficiency reasons the maxium of the function is Q2 dependent
378 
379  // Locate the pion in the decay products
380  // at this point we already know that the pion is unique so the first pion we find is our pion
381  unsigned int pi_id = 0 ;
382 
383  for(unsigned int iparticle = 0; iparticle < nd; iparticle++) {
384 
385  if ( genie::pdg::IsPion( ch->DaughterPdgCode(iparticle) ) ) {
386  pi_id = iparticle ;
387  break ;
388  }
389  }//iparticle
390 
391  TLorentzVector * lab_pion = fPhaseSpaceGenerator.GetDecay(pi_id);
392 
393  accept_decay = AcceptPionDecay( *lab_pion, decay_particle_id, event) ;
394 
395  } //if it is a Delta -> N + Pi
396 
397  }//accept_decay
398 
399  }//fGenerateWeighted
400 
401  // A decay was generated - Copy to the event record
402 
403  // Check whether the interaction is off a nuclear target or free nucleon
404  // Depending on whether this module is run before or after the hadron
405  // transport module it would affect the daughters status code
406  GHepParticle * target_nucleus = event->TargetNucleus();
407  bool in_nucleus = (target_nucleus!=0);
408 
409  // Loop over daughter list and add corresponding GHepParticles
410  for(unsigned int id = 0; id < nd; id++) {
411 
412  int daughter_pdg_code = pdgc[id];
413 
414  TLorentzVector * daughter_p4 = fPhaseSpaceGenerator.GetDecay(id);
415  LOG("ResonanceDecay", pDEBUG)
416  << "Adding daughter particle with PDG code = " << pdgc[id]
417  << " and mass = " << mass[id] << " GeV";
418 
419  bool is_hadron = pdg::IsHadron(daughter_pdg_code);
420  bool hadron_in_nuc = (in_nucleus && is_hadron && fRunBefHadroTransp);
421 
422  GHepStatus_t daughter_status_code = (hadron_in_nuc) ?
424 
425  event->AddParticle(
426  daughter_pdg_code, daughter_status_code, decay_particle_id,-1,-1,-1,
427  *daughter_p4, decay_particle_x4);
428  }
429 
430  return true ;
431 }
const int kPdgP33m1232_DeltaPP
Definition: PDGCodes.h:107
bool IsPion(int pdgc)
Definition: PDGUtils.cxx:326
static RandomGen * Instance()
Access instance.
Definition: RandomGen.cxx:71
const TLorentzVector * P4(void) const
Definition: GHepParticle.h:78
static const unsigned int kMaxUnweightDecayIterations
Definition: Controls.h:61
A singleton holding random number generator classes. All random number generation in GENIE should tak...
Definition: RandomGen.h:29
const int kPdgP33m1232_DeltaP
Definition: PDGCodes.h:106
int Pdg(void) const
Definition: GHepParticle.h:63
bool IsHadron(int pdgc)
Definition: PDGUtils.cxx:392
#define LOG(stream, priority)
A macro that returns the requested log4cpp::Category appending a string (using the FILE...
Definition: Messenger.h:96
bool IsPiNDecayChannel(TDecayChannel *ch) const
bool fRunBefHadroTransp
is invoked before or after FSI?
Definition: Decayer.h:57
#define pINFO
Definition: Messenger.h:62
bool fGenerateWeighted
generate weighted or unweighted decays?
Definition: Decayer.h:56
#define pWARN
Definition: Messenger.h:60
const int kPdgP33m1232_Delta0
Definition: PDGCodes.h:105
static PDGLibrary * Instance(void)
Definition: PDGLibrary.cxx:68
const TLorentzVector * X4(void) const
Definition: GHepParticle.h:79
bool AcceptPionDecay(TLorentzVector lab_pion, int dec_part_id, const GHepRecord *event) const
TParticlePDG * Find(int pdgc, bool must_exist=true)
Definition: PDGLibrary.cxx:86
#define SLOG(stream, priority)
A macro that returns the requested log4cpp::Category appending a short string (using the FUNCTION and...
Definition: Messenger.h:84
TRandom3 & RndDec(void) const
rnd number generator used by decay models
Definition: RandomGen.h:56
STDHEP-like event record entry that can fit a particle or a nucleus.
Definition: GHepParticle.h:39
enum genie::EGHepStatus GHepStatus_t
#define pDEBUG
Definition: Messenger.h:63
TObjArray * BaryonResonanceDecayer::EvolveDeltaBR ( int  dec_part_pdgc,
TObjArray *  decay_list,
double  W 
) const
private

Definition at line 433 of file BaryonResonanceDecayer.cxx.

References EvolveDeltaDecayWidth().

Referenced by SelectDecayChannel().

433  {
434 
435  unsigned int nch = decay_list -> GetEntries();
436 
437  std::vector<double> widths( nch, 0. ) ;
438  double tot = 0. ;
439 
440  TDecayChannel * temp = nullptr ;
441 
442  for ( unsigned int i = 0 ; i < nch ; ++i ) {
443 
444  temp = (TDecayChannel*) decay_list -> At(i) ;
445  tot += widths[i] = EvolveDeltaDecayWidth(dec_part_pdgc, temp, W ) ;
446 
447  }
448 
449  if ( tot <= 0. ) return nullptr ;
450 
451  TObjArray * new_list = new TObjArray() ;
452 
453  TDecayChannel * update = nullptr ;
454 
455  for ( unsigned int i = 0 ; i < nch ; ++i ) {
456 
457  if ( widths[i] <= 0. ) continue ;
458 
459  temp = (TDecayChannel*) decay_list -> At(i) ;
460 
461  unsigned int nd = temp -> NDaughters() ;
462  std::vector<Int_t> ds( nd, 0 ) ;
463  for ( unsigned int d = 0 ; d < nd; ++d ) {
464  ds[d] = temp -> DaughterPdgCode(d) ;
465  }
466 
467  update = new TDecayChannel(
468  temp -> Number(),
469  temp -> MatrixElementCode(),
470  widths[i] / tot,
471  nd,
472  & ds[0]
473  ) ;
474 
475  new_list -> Add( update ) ;
476  }
477 
478  new_list -> SetOwner(kFALSE);
479 
480  return new_list ;
481 }
double EvolveDeltaDecayWidth(int dec_part_pdgc, TDecayChannel *ch, double W) const
double W(const Interaction *const i)
Definition: KineUtils.cxx:1101
double BaryonResonanceDecayer::EvolveDeltaDecayWidth ( int  dec_part_pdgc,
TDecayChannel *  ch,
double  W 
) const
private

Definition at line 484 of file BaryonResonanceDecayer.cxx.

References fFFScaling, FinalStateMass(), genie::utils::res::FromPdgCode(), genie::pdg::IsNucleon(), genie::pdg::IsPion(), genie::pdg::IsProton(), genie::constants::kNucleonMass, genie::kPdgPiP, genie::constants::kPi0Mass, genie::constants::kPionMass, genie::constants::kProtonMass, genie::units::m, genie::utils::res::Mass(), genie::utils::kinematics::W(), and genie::utils::res::Width().

Referenced by EvolveDeltaBR().

484  {
485 
486  /*
487  * The decay widths of the Delta in Pions or in N gammas are not constant.
488  * They depend on the actual mass of the decaying delta (W) they need to be evolved accordingly.
489  * This method tweaks the Delta branching ratios as a function of the W and
490  * returns the proper one depending on the specific decay channel.
491  */
492 
493  // identify the decay channel
494  // The delta decays only in 3 ways
495  // Delta -> Charged Pi + N
496  // Delta -> Pi0 + N
497  // Delta -> Gamma + N
498 
499  // They have evolution as a function of W that are different if the final state has pions or not
500  // so having tagged the pion is enough for the purpose of this method.
501 
502  bool has_pion = false ;
503  int pion_id = -1 ;
504  int nucleon_id = -1 ;
505  unsigned int nd = ch -> NDaughters() ;
506  for(unsigned int i = 0 ; i < nd; ++i ) {
507  if ( genie::pdg::IsPion( ch -> DaughterPdgCode(i) ) ) {
508  has_pion = true ;
509  pion_id = i ;
510  }
511 
512  if ( genie::pdg::IsNucleon( ch -> DaughterPdgCode(i) ) ) {
513  nucleon_id = i ;
514  }
515  }
516 
517 
518  // The first and most trivial evolution of the Width as a function of W
519  // is that if W is lower then the final state mass the width collapses to 0.
520 
521  if ( W < this -> FinalStateMass( ch ) ) {
522 
523  return 0. ;
524 
525  }
526 
527  // At this point, W is high enough to assume the decay of the delta in this channel
528  //
529  // The amplitude dependencies on W scales with the momentum of the pion or the photon respectivelly
530  // following these relationships
531  //
532  // (p_pi(W))^3
533  // Ampl_pi(W) = Ampl_pi(def)x---------------
534  // (p_pi(def))^3
535  //
536  //
537  // (p_ga(W))^3 (F_ga(W))^2
538  // Ampl_ga(W) = Ampl_ga(def)x--------------- x ---------------
539  // (p_ga(def))^3 (F_ga(def))^2
540  //
541  // where the "def" stand for the nominal value of the Delta mass.
542  // - pi_* are the momentum of the gamma and of the pion coming from the decay
543  // - F_ga is the form factor
544  //
545  // So the new amplitudes are evaluated and the proper value is returned
546 
547  // Getting the delta resonance from GENIE database
548  Resonance_t res = genie::utils::res::FromPdgCode( dec_part_pdgc ) ;
549 
550  double m = genie::utils::res::Mass( res ) ;
551  double m_2 = TMath::Power(m, 2);
552 
553  double mN = genie::pdg::IsProton( ch -> DaughterPdgCode( nucleon_id ) ) ? genie::constants::kProtonMass : genie::constants::kNucleonMass ;
554  double mN_2 = TMath::Power( mN, 2);
555 
556  double W_2 = TMath::Power(W, 2);
557 
558  double scaling = 0. ;
559 
560  if ( has_pion ) {
561 
562  double mPion = TMath::Abs( ch -> DaughterPdgCode( pion_id ) ) == kPdgPiP ? genie::constants::kPionMass : genie::constants::kPi0Mass ;
563  double m_aux1= TMath::Power( mN + mPion, 2) ;
564  double m_aux2= TMath::Power( mN - mPion, 2) ;
565 
566  // momentum of the pion in the Delta reference frame
567  double pPi_W = TMath::Sqrt((W_2-m_aux1)*(W_2-m_aux2))/(2*W); // at W
568  double pPi_m = TMath::Sqrt((m_2-m_aux1)*(m_2-m_aux2))/(2*m); // at the default Delta mass
569 
570  scaling = TMath::Power( pPi_W / pPi_m , 3 ) ;
571 
572  }
573  else {
574 
575  // momentum of the photon in the Delta Reference frame = Energy of the photon
576  double Egamma_W = (W_2-mN_2)/(2*W); // at W
577  double Egamma_m = (m_2-mN_2)/(2*m); // at the default Delta mass
578 
579  // form factor of the photon production
580  double fgamma_W = 1./(TMath::Power(1+Egamma_W*Egamma_W/fFFScaling, 2));
581  double fgamma_m = 1./(TMath::Power(1+Egamma_m*Egamma_m/fFFScaling, 2));
582 
583  scaling = TMath::Power( Egamma_W / Egamma_m, 3 ) * TMath::Power( fgamma_W / fgamma_m , 2 ) ;
584  }
585 
586  // get the width of the delta and obtain the width of the decay in the channel we are evolving
587  // evaluated at the nominal mass of the delta
588  double defChWidth = ch -> BranchingRatio() * genie::utils::res::Width( res ) ;
589 
590  return defChWidth * scaling ;
591 
592 }
bool IsPion(int pdgc)
Definition: PDGUtils.cxx:326
static const double kNucleonMass
bool IsNucleon(int pdgc)
Definition: PDGUtils.cxx:346
double Mass(Resonance_t res)
resonance mass (GeV)
double Width(Resonance_t res)
resonance width (GeV)
enum genie::EResonance Resonance_t
double W(const Interaction *const i)
Definition: KineUtils.cxx:1101
bool IsProton(int pdgc)
Definition: PDGUtils.cxx:336
const int kPdgPiP
Definition: PDGCodes.h:158
double FinalStateMass(TDecayChannel *ch) const
Resonance_t FromPdgCode(int pdgc)
PDG code -&gt; resonance id.
static constexpr double m
Definition: Units.h:71
double BaryonResonanceDecayer::FinalStateMass ( TDecayChannel *  ch) const
private

Definition at line 686 of file BaryonResonanceDecayer.cxx.

References genie::PDGLibrary::Find(), genie::PDGLibrary::Instance(), LOG, and pNOTICE.

Referenced by EvolveDeltaDecayWidth(), and SelectDecayChannel().

687 {
688 // Computes the total mass of the final state system
689 
690  double mass = 0;
691  unsigned int nd = ch->NDaughters();
692 
693  for(unsigned int iparticle = 0; iparticle < nd; iparticle++) {
694 
695  int daughter_code = ch->DaughterPdgCode(iparticle);
696  TParticlePDG * daughter = PDGLibrary::Instance()->Find(daughter_code);
697  assert(daughter);
698 
699  double md = daughter->Mass();
700 
701  // hack to switch off channels giving rare occurences of |1114| that has
702  // no decay channels in the pdg table (08/2007)
703  if(TMath::Abs(daughter_code) == 1114) {
704  LOG("ResonanceDecay", pNOTICE)
705  << "Disabling decay channel containing resonance 1114";;
706  md = 999999999;
707  }
708  mass += md;
709  }
710  return mass;
711 }
#define LOG(stream, priority)
A macro that returns the requested log4cpp::Category appending a string (using the FILE...
Definition: Messenger.h:96
static PDGLibrary * Instance(void)
Definition: PDGLibrary.cxx:68
TParticlePDG * Find(int pdgc, bool must_exist=true)
Definition: PDGLibrary.cxx:86
#define pNOTICE
Definition: Messenger.h:61
double BaryonResonanceDecayer::FindDistributionExtrema ( unsigned int  i,
bool  find_maximum = false 
) const
private

Definition at line 812 of file BaryonResonanceDecayer.cxx.

References fMaxTolerance, fRParams, genie::RandomGen::Instance(), genie::constants::kPi, LOG, MinusPionAngularDist(), pDEBUG, pINFO, and PionAngularDist().

Referenced by AcceptPionDecay(), and LoadConfig().

812  {
813 
814  // Choose method upon creation between:
815  // kConjugateFR, kConjugatePR, kVectorBFGS,
816  // kVectorBFGS2, kSteepestDescent
817  ROOT::Math::GSLMinimizer min( ROOT::Math::kVectorBFGS );
818 
819  min.SetMaxFunctionCalls(1000);
820  min.SetMaxIterations(1000);
821  min.SetTolerance( fMaxTolerance );
822 
823  ROOT::Math::WrappedParamFunction<ROOT::Math::FreeParamMultiFunctionPtr> f( ( find_maximum ?
826  2, 3, fRParams[q2_bin] ) ;
827 
828  // Steps are defined as the same fraction of the range of each variable
829  double step[2] = { 0.00005 * kPi, 0.00005 * 2 * kPi } ;
830 
831  min.SetFunction(f);
832 
833  do {
834 
835  // Set the free variables to be minimized!
836  // it has been observed that some initial values are making the minimization to fail.
837  // e.g. ( pi/2, pi/2 )
838  // at the same time, the absolute extrema seems very stable with respect to changes of the initial variable
839  // hence the minimization is done inside a loop where the variables a initialized randomly
840 
841  min.SetLimitedVariable( 0, "theta", kPi * RandomGen::Instance()-> RndDec().Rndm(), step[0], 0., kPi );
842  min.SetLimitedVariable( 1, "phi", 2*kPi * RandomGen::Instance()-> RndDec().Rndm(), step[1], 0., 2*kPi );
843 
844  } while( ! min.Minimize() ) ;
845 
846  const double *xs = min.X();
847 
848  double result = find_maximum ? -1 * f( xs ) : f( xs ) ;
849 
850  LOG("BaryonResonanceDecayer", pINFO) << (find_maximum ? "Maximum " : "Minimum ")
851  << "of angular distribution found in ( "
852  << xs[0] << ", " << xs[1] << " ): "
853  << result ;
854 
855  LOG("BaryonResonanceDecayer", pDEBUG) << "Minimum found in " << min.NCalls() << " calls" ;
856 
857  return result ;
858 
859 }
std::vector< double * > fRParams
static RandomGen * Instance()
Access instance.
Definition: RandomGen.cxx:71
#define LOG(stream, priority)
A macro that returns the requested log4cpp::Category appending a string (using the FILE...
Definition: Messenger.h:96
#define pINFO
Definition: Messenger.h:62
static double MinusPionAngularDist(const double *x, const double *par)
static double PionAngularDist(const double *x, const double *par)
#define pDEBUG
Definition: Messenger.h:63
bool BaryonResonanceDecayer::HasEvolvedBRs ( int  dec_part_pdgc)
staticprivate

Definition at line 786 of file BaryonResonanceDecayer.cxx.

References genie::kPdgP33m1232_Delta0, and genie::kPdgP33m1232_DeltaP.

Referenced by SelectDecayChannel().

786  {
787 
788  dec_part_pdgc = abs( dec_part_pdgc ) ;
789 
790  // the evolution of the Delta BR as a function of W is meaningful only when there are
791  // more than one decay channels.
792  // Delta++ and Delta- have only one decay channel bacause of baryon number and charge conservation
793 
794  return ( dec_part_pdgc == kPdgP33m1232_Delta0 ||
795  dec_part_pdgc == kPdgP33m1232_DeltaP ) ;
796 }
const int kPdgP33m1232_DeltaP
Definition: PDGCodes.h:106
const int kPdgP33m1232_Delta0
Definition: PDGCodes.h:105
void BaryonResonanceDecayer::InhibitDecay ( int  pdgc,
TDecayChannel *  ch = 0 
) const
privatevirtual

Implements genie::Decayer.

Definition at line 756 of file BaryonResonanceDecayer.cxx.

References IsHandled().

757 {
758  if(! this->IsHandled(pdgc)) return;
759  if(!dc) return;
760 
761  //
762  // Not implemented
763  //
764 }
void BaryonResonanceDecayer::Initialize ( void  ) const
private

Definition at line 740 of file BaryonResonanceDecayer.cxx.

Referenced by BaryonResonanceDecayer().

741 {
742 
743 }
bool BaryonResonanceDecayer::IsDelta ( int  dec_part_pdgc)
staticprivate

Definition at line 776 of file BaryonResonanceDecayer.cxx.

References genie::kPdgP33m1232_Delta0, genie::kPdgP33m1232_DeltaM, genie::kPdgP33m1232_DeltaP, and genie::kPdgP33m1232_DeltaPP.

776  {
777 
778  dec_part_pdgc = abs( dec_part_pdgc ) ;
779 
780  return ( dec_part_pdgc == kPdgP33m1232_DeltaM ||
781  dec_part_pdgc == kPdgP33m1232_Delta0 ||
782  dec_part_pdgc == kPdgP33m1232_DeltaP ||
783  dec_part_pdgc == kPdgP33m1232_DeltaPP ) ;
784 }
const int kPdgP33m1232_DeltaPP
Definition: PDGCodes.h:107
const int kPdgP33m1232_DeltaP
Definition: PDGCodes.h:106
const int kPdgP33m1232_DeltaM
Definition: PDGCodes.h:104
const int kPdgP33m1232_Delta0
Definition: PDGCodes.h:105
bool BaryonResonanceDecayer::IsHandled ( int  pdgc) const
privatevirtual

Implements genie::Decayer.

Definition at line 745 of file BaryonResonanceDecayer.cxx.

References genie::utils::res::IsBaryonResonance(), LOG, and pDEBUG.

Referenced by InhibitDecay(), ProcessEventRecord(), and UnInhibitDecay().

746 {
747  bool is_handled = utils::res::IsBaryonResonance(pdg_code);
748 
749  LOG("ResonanceDecay", pDEBUG)
750  << "Can decay particle with PDG code = " << pdg_code
751  << "? " << ((is_handled)? "Yes" : "No");
752 
753  return is_handled ;
754 }
#define LOG(stream, priority)
A macro that returns the requested log4cpp::Category appending a string (using the FILE...
Definition: Messenger.h:96
bool IsBaryonResonance(int pdgc)
is input a baryon resonance?
#define pDEBUG
Definition: Messenger.h:63
bool BaryonResonanceDecayer::IsPiNDecayChannel ( TDecayChannel *  ch) const
private

Definition at line 713 of file BaryonResonanceDecayer.cxx.

References genie::pdg::IsNucleon(), and genie::pdg::IsPion().

Referenced by DecayExclusive().

714 {
715  if(!ch) return false;
716 
717  unsigned int nd = ch->NDaughters();
718  if(nd != 2) return false;
719 
720  int npi = 0;
721  int nnucl = 0;
722 
723  for(unsigned int iparticle = 0; iparticle < nd; iparticle++) {
724 
725  int daughter_code = ch->DaughterPdgCode(iparticle);
726 
727  if( genie::pdg::IsPion( daughter_code ) )
728  npi++;
729 
730  if ( genie::pdg::IsNucleon(daughter_code ) )
731  nnucl++;
732 
733  }//iparticle
734 
735  if(npi == 1 && nnucl == 1) return true;
736 
737  return false;
738 }
bool IsPion(int pdgc)
Definition: PDGUtils.cxx:326
bool IsNucleon(int pdgc)
Definition: PDGUtils.cxx:346
void BaryonResonanceDecayer::LoadConfig ( void  )
virtual

Reimplemented from genie::Decayer.

Definition at line 863 of file BaryonResonanceDecayer.cxx.

References fDeltaThetaOnly, fFFScaling, FindDistributionExtrema(), fMaxTolerance, fQ2Thresholds, fR31, fR33, fR3m1, fRParams, fW_max, genie::Algorithm::GetParam(), genie::Algorithm::GetParamDef(), genie::Algorithm::GetParamVect(), genie::Decayer::LoadConfig(), LOG, and pFATAL.

863  {
864 
866 
867  this -> GetParam( "FFScaling", fFFScaling ) ;
868 
869  this -> GetParamDef( "Delta-ThetaOnly", fDeltaThetaOnly, true ) ;
870 
871  this -> GetParamDef( "DeltaDecayMaximumTolerance", fMaxTolerance, 0.0005 ) ;
872 
873  bool invalid_configuration = false ;
874 
875  // load R33 parameters
876  this -> GetParamVect( "Delta-R33", fR33 ) ;
877 
878  // load Q2 thresholds if necessary
879  if ( fR33.size() > 1 ) {
880  this -> GetParamVect("Delta-Q2", fQ2Thresholds ) ;
881  }
882  else {
883  fQ2Thresholds.clear() ;
884  }
885 
886  // check if the number of Q2 matches the number of R33
887  if ( fQ2Thresholds.size() != fR33.size() -1 ) {
888  invalid_configuration = true ;
889  LOG("BaryonResonanceDecayer", pFATAL) << "Delta-Q2 and Delta-R33 have wrong sizes" ;
890  LOG("BaryonResonanceDecayer", pFATAL) << "Delta-Q2 -> " << fQ2Thresholds.size() ;
891  LOG("BaryonResonanceDecayer", pFATAL) << "Delta-R33 -> " << fR33.size() ;
892  }
893 
894  if ( fDeltaThetaOnly ) {
895 
896  // check the parameters validity
897  for ( unsigned int i = 0 ; i < fR33.size(); ++i ) {
898  if ( (fR33[i] < -0.5) || (fR33[i] > 1.) ) {
899  invalid_configuration = true ;
900  LOG("BaryonResonanceDecayer", pFATAL) << "Delta-R33[" << i << "] out of valid range [-0.5 ; 1 ]" ;
901  LOG("BaryonResonanceDecayer", pFATAL) << "Delta-R33[" << i << "] = " << fR33[i] ;
902  break ;
903  }
904  }
905 
906  // set appropriate maxima
907  fW_max.resize( fR33.size(), 0. ) ;
908  for ( unsigned int i = 0 ; i < fR33.size(); ++i ) {
909  fW_max[i] = ( fR33[i] < 0.5 ? 2. * ( 1. - fR33[i] ) : fR33[i] + 0.5 ) + fMaxTolerance ;
910  }
911 
912  } // Delta Theta Only
913 
914  else {
915 
916  // load R31 and R3m1 parameters
917  this -> GetParamVect( "Delta-R31", fR31 ) ;
918 
919  this -> GetParamVect( "Delta-R3m1", fR3m1 ) ;
920 
921  // check if they match the numbers of R33
922  if ( (fR31.size() != fR33.size()) || (fR3m1.size() != fR33.size()) ) {
923  LOG("BaryonResonanceDecayer", pFATAL) << "Delta-R31 or Delta-R3m1 sizes don't match Delta-R33" ;
924  LOG("BaryonResonanceDecayer", pFATAL) << "R31: " << fR31.size()
925  << ", R3m1: " << fR31.size()
926  << " while R33: " << fR33.size() ;
927  invalid_configuration = true ;
928  }
929 
930  for ( unsigned int i = 0; i < fRParams.size() ; ++i ) {
931  delete [] fRParams[i] ;
932  }
933  fRParams.clear() ;
934  // fill the container by Q2 bin instead of the parmaeter bin
935  for ( unsigned int i = 0 ; i < fR33.size(); ++i ) {
936  fRParams.push_back( new double[3]{ fR33[i], fR31[i], fR3m1[i] } ) ;
937  }
938 
939 
940  // check if they are physical
941  fW_max.resize( fR33.size(), 0. ) ;
942  for ( unsigned int i = 0 ; i < fR33.size(); ++i ) {
943 
944  double temp_min = FindDistributionExtrema( i, false ) ;
945  if ( temp_min < 0. ) {
946  LOG("BaryonResonanceDecayer", pFATAL) << "pion angular distribution minimum is negative for Q2 bin " << i ;
947  invalid_configuration = true ;
948  break ;
949  }
950 
951  double temp_max = FindDistributionExtrema( i, true ) ;
952  if ( temp_max <= 0. ) {
953  LOG("BaryonResonanceDecayer", pFATAL) << "pion angular distribution maximum is non positive for Q2 bin " << i ;
954  invalid_configuration = true ;
955  break ;
956  }
957 
958  fW_max[i] = temp_max + fMaxTolerance ;
959 
960  }
961 
962  }
963 
964  if ( invalid_configuration ) {
965 
966  LOG("BaryonResonanceDecayer", pFATAL)
967  << "Invalid configuration: Exiting" ;
968 
969  // From the FreeBSD Library Functions Manual
970  //
971  // EX_CONFIG (78) Something was found in an unconfigured or miscon-
972  // figured state.
973 
974  exit( 78 ) ;
975 
976  }
977 
978 }
std::vector< double * > fRParams
#define pFATAL
Definition: Messenger.h:56
int GetParamVect(const std::string &comm_name, std::vector< T > &v, bool is_top_call=true) const
Handle to load vectors of parameters.
double FindDistributionExtrema(unsigned int i, bool find_maximum=false) const
#define LOG(stream, priority)
A macro that returns the requested log4cpp::Category appending a string (using the FILE...
Definition: Messenger.h:96
virtual void LoadConfig(void)
Definition: Decayer.cxx:135
bool GetParamDef(const RgKey &name, T &p, const T &def) const
bool GetParam(const RgKey &name, T &p, bool is_top_call=true) const
static double genie::BaryonResonanceDecayer::MinusPionAngularDist ( const double *  x,
const double *  par 
)
inlinestaticprivate

Definition at line 74 of file BaryonResonanceDecayer.h.

References PionAngularDist().

Referenced by FindDistributionExtrema().

74  { // this is used to find the maxima of the previous function
75  return -1. * BaryonResonanceDecayer::PionAngularDist( x, par ) ;
76  }
static double PionAngularDist(const double *x, const double *par)
double BaryonResonanceDecayer::PionAngularDist ( const double *  x,
const double *  par 
)
staticprivate

Definition at line 798 of file BaryonResonanceDecayer.cxx.

References genie::constants::kSqrt3.

Referenced by AcceptPionDecay(), FindDistributionExtrema(), and MinusPionAngularDist().

798  {
799 
800  double c_t = TMath::Cos( x[0] ) ;
801  double s_t = TMath::Sin( x[0] ) ;
802 
803  double c_phi = TMath::Cos( x[1 ] );
804 
805  double theta_dep_only = 1. - ( par[0] - 0.5 )*( 3.*c_t*c_t - 1. ) ;
806  double phi_dependency = kSqrt3 *( 2.*par[1]*s_t*c_t*c_phi + par[2]*s_t*(2.*c_phi*c_phi-1.) ) ;
807 
808  return theta_dep_only - phi_dependency ;
809 
810 }
void BaryonResonanceDecayer::ProcessEventRecord ( GHepRecord event) const
virtual

Implements genie::EventRecordVisitorI.

Definition at line 62 of file BaryonResonanceDecayer.cxx.

References Decay(), genie::Decayer::fRunBefHadroTransp, IsHandled(), genie::kHadroSysGenErr, LOG, genie::GHepParticle::Name(), pDEBUG, genie::GHepParticle::Pdg(), pINFO, pNOTICE, pWARN, return, genie::exceptions::EVGThreadException::SetReason(), genie::GHepParticle::Status(), genie::exceptions::EVGThreadException::SwitchOnFastForward(), and genie::Decayer::ToBeDecayed().

63 {
64  LOG("ResonanceDecay", pINFO)
65  << "Running resonance decayer "
66  << ((fRunBefHadroTransp) ? "*before*" : "*after*") << " FSI";
67 
68  // Loop over particles, find unstable ones and decay them
69  TObjArrayIter piter(event);
70  GHepParticle * p = 0;
71  int ipos = -1;
72 
73  while( (p = (GHepParticle *) piter.Next()) ) {
74 
75  ipos++;
76  LOG("ResonanceDecay", pDEBUG) << "Checking: " << p->Name();
77 
78  int pdg_code = p->Pdg();
79  GHepStatus_t status_code = p->Status();
80 
81  // std::cout << "Decaing particle " << ipos << " with PDG " << pdg_code << std::endl ;
82 
83  if(!this->IsHandled (pdg_code)) continue;
84  if(!this->ToBeDecayed(pdg_code, status_code)) continue;
85 
86  LOG("ResonanceDecay", pNOTICE)
87  << "Decaying unstable particle: " << p->Name();
88 
89  bool decayed = this->Decay(ipos, event);
90  if ( ! decayed ) {
91  LOG("ResonanceDecay", pWARN) << "Resonance not decayed!" ;
92  LOG("ResonanceDecay", pWARN) << "Quitting the current event generation thread" ;
93 
94  event -> EventFlags() -> SetBitNumber(kHadroSysGenErr, true);
95 
97  exception.SetReason("Resonance not decayed");
98  exception.SwitchOnFastForward();
99  throw exception;
100 
101  return ;
102  }
103 
104  } // loop over particles
105 
106  LOG("ResonanceDecay", pNOTICE)
107  << "Done finding & decaying baryon resonances";
108 }
virtual bool ToBeDecayed(int pdgc, GHepStatus_t ist) const
Definition: Decayer.cxx:51
bool Decay(int dec_part_id, GHepRecord *event) const
GHepStatus_t Status(void) const
Definition: GHepParticle.h:64
int Pdg(void) const
Definition: GHepParticle.h:63
string Name(void) const
Name that corresponds to the PDG code.
An exception thrown by EventRecordVisitorI when the normal processing sequence has to be disrupted (f...
#define LOG(stream, priority)
A macro that returns the requested log4cpp::Category appending a string (using the FILE...
Definition: Messenger.h:96
bool fRunBefHadroTransp
is invoked before or after FSI?
Definition: Decayer.h:57
#define pINFO
Definition: Messenger.h:62
#define pWARN
Definition: Messenger.h:60
#define pNOTICE
Definition: Messenger.h:61
STDHEP-like event record entry that can fit a particle or a nucleus.
Definition: GHepParticle.h:39
enum genie::EGHepStatus GHepStatus_t
#define pDEBUG
Definition: Messenger.h:63
TDecayChannel * BaryonResonanceDecayer::SelectDecayChannel ( int  dec_part_id,
GHepRecord event,
bool &  to_be_deleted 
) const
private

Definition at line 157 of file BaryonResonanceDecayer.cxx.

References EvolveDeltaBR(), FinalStateMass(), genie::PDGLibrary::Find(), HasEvolvedBRs(), genie::RandomGen::Instance(), genie::PDGLibrary::Instance(), LOG, genie::GHepParticle::P4(), genie::utils::print::P4AsString(), pDEBUG, genie::GHepParticle::Pdg(), pERROR, pINFO, pWARN, genie::RandomGen::RndDec(), SLOG, and genie::utils::kinematics::W().

Referenced by Decay().

160 {
161  // Get particle to be decayed
162  GHepParticle * decay_particle = event->Particle(decay_particle_id);
163  if(!decay_particle) return 0;
164 
165  // Get the particle 4-momentum and PDG code
166  TLorentzVector decay_particle_p4 = *(decay_particle->P4());
167  int decay_particle_pdg_code = decay_particle->Pdg();
168 
169  // Find the particle in the PDG library & quit if it does not exist
170  TParticlePDG * mother =
171  PDGLibrary::Instance()->Find(decay_particle_pdg_code);
172  if(!mother) {
173  LOG("ResonanceDecay", pERROR)
174  << "\n *** The particle with PDG code = " << decay_particle_pdg_code
175  << " was not found in PDGLibrary";
176  return 0;
177  }
178  LOG("ResonanceDecay", pINFO)
179  << "Decaying a " << mother->GetName()
180  << " with P4 = " << utils::print::P4AsString(&decay_particle_p4);
181 
182  // Get the resonance mass W (generally different from the mass associated
183  // with the input PDG code, since the it is produced off the mass shell)
184  double W = decay_particle_p4.M();
185  LOG("ResonanceDecay", pINFO) << "Available mass W = " << W;
186 
187  // Get all decay channels
188  TObjArray * original_decay_list = mother->DecayList();
189 
190  unsigned int nch = original_decay_list -> GetEntries();
191  LOG("ResonanceDecay", pINFO)
192  << mother->GetName() << " has: " << nch << " decay channels";
193 
194  // Loop over the decay channels (dc) and write down the branching
195  // ratios to be used for selecting a decay channel.
196  // Since a baryon resonance can be created at W < Mres, explicitly
197  // check and inhibit decay channels for which W > final-state-mass
198 
199  bool has_evolved_brs = BaryonResonanceDecayer::HasEvolvedBRs( decay_particle_pdg_code ) ;
200 
201  TObjArray * actual_decay_list = nullptr ;
202 
203  if ( has_evolved_brs ) {
204  actual_decay_list = EvolveDeltaBR( decay_particle_pdg_code, original_decay_list, W ) ;
205  if ( ! actual_decay_list ) return nullptr ;
206  nch = actual_decay_list -> GetEntries() ;
207  to_be_deleted = true ;
208  }
209  else {
210  actual_decay_list = original_decay_list ;
211  to_be_deleted = false ;
212  }
213 
214  double BR[nch], tot_BR = 0;
215 
216  for(unsigned int ich = 0; ich < nch; ich++) {
217 
218  TDecayChannel * ch = (TDecayChannel *) actual_decay_list -> At(ich);
219 
220  double fsmass = this->FinalStateMass(ch) ;
221  if ( fsmass < W ) {
222 
223  SLOG("ResonanceDecay", pDEBUG)
224  << "Using channel: " << ich
225  << " with final state mass = " << fsmass << " GeV";
226 
227  tot_BR += ch->BranchingRatio();
228 
229  } else {
230  SLOG("ResonanceDecay", pINFO)
231  << "Suppresing channel: " << ich
232  << " with final state mass = " << fsmass << " GeV";
233  } // final state mass
234 
235  BR[ich] = tot_BR;
236  }//channel loop
237 
238  if( tot_BR <= 0. ) {
239  SLOG("ResonanceDecay", pWARN)
240  << "None of the " << nch << " decay channels is available @ W = " << W;
241  return 0;
242  }
243 
244  // Select a resonance based on the branching ratios
245  unsigned int ich = 0, sel_ich; // id of selected decay channel
246  RandomGen * rnd = RandomGen::Instance();
247  double x = tot_BR * rnd->RndDec().Rndm();
248  do {
249  sel_ich = ich;
250  } while (x > BR[ich++]);
251 
252  TDecayChannel * sel_ch = (TDecayChannel *) actual_decay_list -> At(sel_ich);
253 
254  LOG("ResonanceDecay", pINFO)
255  << "Selected " << sel_ch->NDaughters() << "-particle decay channel ("
256  << sel_ich << ") has BR = " << sel_ch->BranchingRatio();
257 
258  if ( has_evolved_brs ) {
259 
260  for ( unsigned int i = 0; i < nch; ++i) {
261  if ( sel_ich != i ) delete actual_decay_list -> At(i);
262  }
263 
264  delete actual_decay_list ;
265  }
266 
267  return sel_ch;
268 }
#define pERROR
Definition: Messenger.h:59
static RandomGen * Instance()
Access instance.
Definition: RandomGen.cxx:71
const TLorentzVector * P4(void) const
Definition: GHepParticle.h:78
static bool HasEvolvedBRs(int dec_part_pdgc)
string P4AsString(const TLorentzVector *p)
Definition: PrintUtils.cxx:27
A singleton holding random number generator classes. All random number generation in GENIE should tak...
Definition: RandomGen.h:29
double W(const Interaction *const i)
Definition: KineUtils.cxx:1101
int Pdg(void) const
Definition: GHepParticle.h:63
#define LOG(stream, priority)
A macro that returns the requested log4cpp::Category appending a string (using the FILE...
Definition: Messenger.h:96
TObjArray * EvolveDeltaBR(int dec_part_pdgc, TObjArray *decay_list, double W) const
double FinalStateMass(TDecayChannel *ch) const
#define pINFO
Definition: Messenger.h:62
#define pWARN
Definition: Messenger.h:60
static PDGLibrary * Instance(void)
Definition: PDGLibrary.cxx:68
TParticlePDG * Find(int pdgc, bool must_exist=true)
Definition: PDGLibrary.cxx:86
#define SLOG(stream, priority)
A macro that returns the requested log4cpp::Category appending a short string (using the FUNCTION and...
Definition: Messenger.h:84
TRandom3 & RndDec(void) const
rnd number generator used by decay models
Definition: RandomGen.h:56
STDHEP-like event record entry that can fit a particle or a nucleus.
Definition: GHepParticle.h:39
#define pDEBUG
Definition: Messenger.h:63
void BaryonResonanceDecayer::UnInhibitDecay ( int  pdgc,
TDecayChannel *  ch = 0 
) const
privatevirtual

Implements genie::Decayer.

Definition at line 766 of file BaryonResonanceDecayer.cxx.

References IsHandled().

767 {
768  if(! this->IsHandled(pdgc)) return;
769  if(!dc) return;
770 
771  //
772  // Not implemented
773  //
774 }
double BaryonResonanceDecayer::Weight ( void  ) const
private

Definition at line 681 of file BaryonResonanceDecayer.cxx.

References fWeight.

682 {
683  return fWeight;
684 }

Member Data Documentation

bool genie::BaryonResonanceDecayer::fDeltaThetaOnly
private

Definition at line 85 of file BaryonResonanceDecayer.h.

Referenced by AcceptPionDecay(), and LoadConfig().

double genie::BaryonResonanceDecayer::fFFScaling
private

Definition at line 96 of file BaryonResonanceDecayer.h.

Referenced by EvolveDeltaDecayWidth(), and LoadConfig().

double genie::BaryonResonanceDecayer::fMaxTolerance
private

Definition at line 87 of file BaryonResonanceDecayer.h.

Referenced by FindDistributionExtrema(), and LoadConfig().

TGenPhaseSpace genie::BaryonResonanceDecayer::fPhaseSpaceGenerator
mutableprivate

Definition at line 82 of file BaryonResonanceDecayer.h.

Referenced by DecayExclusive().

std::vector<double> genie::BaryonResonanceDecayer::fQ2Thresholds
private

Definition at line 92 of file BaryonResonanceDecayer.h.

Referenced by AcceptPionDecay(), and LoadConfig().

std::vector<double> genie::BaryonResonanceDecayer::fR31
private

Definition at line 89 of file BaryonResonanceDecayer.h.

Referenced by LoadConfig().

std::vector<double> genie::BaryonResonanceDecayer::fR33
private

Definition at line 89 of file BaryonResonanceDecayer.h.

Referenced by AcceptPionDecay(), and LoadConfig().

std::vector<double> genie::BaryonResonanceDecayer::fR3m1
private

Definition at line 89 of file BaryonResonanceDecayer.h.

Referenced by LoadConfig().

std::vector<double*> genie::BaryonResonanceDecayer::fRParams
private
std::vector<double> genie::BaryonResonanceDecayer::fW_max
private

Definition at line 94 of file BaryonResonanceDecayer.h.

Referenced by AcceptPionDecay(), and LoadConfig().

double genie::BaryonResonanceDecayer::fWeight
mutableprivate

Definition at line 83 of file BaryonResonanceDecayer.h.

Referenced by Decay(), DecayExclusive(), and Weight().


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