genie::SPPEventGenerator Class Reference

Generates resonance single pion production event for the following channels: More...

#include <SPPEventGenerator.h>

Inheritance diagram for genie::SPPEventGenerator:

Collaboration diagram for genie::SPPEventGenerator:

Classes
struct	Cell
struct	Vertex

Public Member Functions
	SPPEventGenerator ()
	SPPEventGenerator (string config)
	~SPPEventGenerator ()
void	ProcessEventRecord (GHepRecord *event_rec) const
void	Configure (const Registry &config)
void	Configure (string config)
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.

Private Member Functions
void	LoadConfig (void)
double	ComputeMaxXSec (const Interaction *interaction) const
int	GetRecoilNucleonPdgCode (Interaction *interaction) const
int	GetFinalPionPdgCode (Interaction *interaction) const

Private Attributes
double	fWcut
int	fMaxDepth
	Maximum depth of dividing parent cell.

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 Member Functions inherited from genie::KineGeneratorWithCache
	KineGeneratorWithCache ()
	KineGeneratorWithCache (string name)
	KineGeneratorWithCache (string name, string config)
	~KineGeneratorWithCache ()
virtual double	ComputeMaxXSec (const Interaction *in, const int nkey) const
virtual double	MaxXSec (GHepRecord *evrec, const int nkey=0) const
virtual double	FindMaxXSec (const Interaction *in, const int nkey=0) const
virtual void	CacheMaxXSec (const Interaction *in, double xsec, const int nkey=0) const
virtual double	Energy (const Interaction *in) const
virtual CacheBranchFx *	AccessCacheBranch (const Interaction *in, const int nkey=0) const
virtual void	AssertXSecLimits (const Interaction *in, double xsec, double xsec_max) 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.
Protected Attributes inherited from genie::KineGeneratorWithCache
const XSecAlgorithmI *	fXSecModel
double	fSafetyFactor
	ComputeMaxXSec -> ComputeMaxXSec * fSafetyFactor.
std::vector< double >	vSafetyFactors
	MaxXSec -> MaxXSec * fSafetyFactors[nkey].
int	fNumOfSafetyFactors
	Number of given safety factors.
std::vector< string >	vInterpolatorTypes
	Type of interpolator for each key in a branch.
int	fNumOfInterpolatorTypes
	Number of given interpolators types.
double	fMaxXSecDiffTolerance
	max{100*(xsec-maxxsec)/.5*(xsec+maxxsec)} if xsec>maxxsec
double	fEMin
	min E for which maxxsec is cached - forcing explicit calc.
bool	fGenerateUniformly
	uniform over allowed phase space + event weight?
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

Generates resonance single pion production event for the following channels:

for the following channels:

      1       nu + p -> l      + p + pi+
      2       nu + n -> l      + p + pi0
      3       nu + n -> l      + n + pi+
      4   antinu + n -> l+     + n + pi-
      5   antinu + p -> l+     + n + pi0
      6   antinu + p -> l+     + p + pi-
      7       nu + p -> nu     + p + pi0
      8       nu + p -> nu     + n + pi+
      9       nu + n -> nu     + n + pi0
      10      nu + n -> nu     + p + pi-
      11  antinu + p -> antinu + p + pi0
      12  antinu + p -> antinu + n + pi+
      13  antinu + n -> antinu + n + pi0
      14  antinu + n -> antinu + p + pi-

Is a concrete implementation of the EventRecordVisitorI interface.

Authors

Igor Kakorin kakor.nosp@m.in@j.nosp@m.inr.r.nosp@m.u, Joint Institute for Nuclear Research
Vadim Naumov vnaum.nosp@m.ov@t.nosp@m.heor..nosp@m.jinr.nosp@m..ru, Joint Institute for Nuclear Research

Created:\n May 9, 2020

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

For the full text of the license visit http://copyright.genie-mc.org or see $GENIE/LICENSE

Definition at line 50 of file SPPEventGenerator.h.

Constructor & Destructor Documentation

SPPEventGenerator() [1/2]

SPPEventGenerator::SPPEventGenerator

(

)

Definition at line 47 of file SPPEventGenerator.cxx.

                                     :
KineGeneratorWithCache("genie::SPPEventGenerator")
{
 
}

References genie::KineGeneratorWithCache::KineGeneratorWithCache().

SPPEventGenerator() [2/2]

SPPEventGenerator::SPPEventGenerator

(

string

config

)

Definition at line 53 of file SPPEventGenerator.cxx.

                                                  :
KineGeneratorWithCache("genie::SPPEventGenerator", config)
{
  
}

References genie::KineGeneratorWithCache::KineGeneratorWithCache().

~SPPEventGenerator()

SPPEventGenerator::~SPPEventGenerator

(

)

Definition at line 59 of file SPPEventGenerator.cxx.

{
  
}

Member Function Documentation

ComputeMaxXSec()

double SPPEventGenerator::ComputeMaxXSec ( const Interaction * interaction ) const

privatevirtual

Implements genie::KineGeneratorWithCache.

Definition at line 342 of file SPPEventGenerator.cxx.

{
   KPhaseSpace * kps = interaction->PhaseSpacePtr();
   Range1D_t Wl = kps->WLim_SPP_iso();
   ROOT::Math::Minimizer * min = ROOT::Math::Factory::CreateMinimizer("Minuit", "Minimize");
   ROOT::Math::IBaseFunctionMultiDim * f = new genie::utils::gsl::d4XSecMK_dWQ2CosThetaPhi_E(fXSecModel, interaction, fWcut);
   min->SetFunction( *f );
   min->SetMaxFunctionCalls(10000);  // for Minuit/Minuit2
   min->SetMaxIterations(10000);     // for GSL
   min->SetTolerance(1e-3);
   min->SetPrintLevel(0);
   double min_xsec = 0.;
   double xsec;
   double step = 1e-7;
   // a heuristic algorithm for maximum search
   int total_cells = (TMath::Power(16, fMaxDepth) - 1)/15;
   vector<Cell> cells(total_cells);
   
   for (int dep = 0; dep < fMaxDepth; dep++)
   {
     int aux = TMath::Power(16, dep) - 1;
     for (int cell = aux/15; cell <= 16*aux/15 ; cell++)
     {
       if (cell == 0)
       {
          cells[cell].Vertex1 = Vertex(0., 0., 0., 0.);
          cells[cell].Vertex2 = Vertex(1., 1., 1., 1.);
       }
       double x1m = (cells[cell].Vertex1.x1 + cells[cell].Vertex2.x1)/2;
       double x2m = (cells[cell].Vertex1.x2 + cells[cell].Vertex2.x2)/2;
       double x3m = (cells[cell].Vertex1.x3 + cells[cell].Vertex2.x3)/2;
       double x4m = (cells[cell].Vertex1.x4 + cells[cell].Vertex2.x4)/2;
       min->SetVariable(0, "x1", x1m, step);
       min->SetVariable(1, "x2", x2m, step);
       min->SetVariable(2, "x3", x3m, step);
       min->SetVariable(3, "x4", x4m, step);
       min->SetVariableLimits(0, cells[cell].Vertex1.x1, cells[cell].Vertex2.x1);
       min->SetVariableLimits(1, cells[cell].Vertex1.x2, cells[cell].Vertex2.x2);
       min->SetVariableLimits(2, cells[cell].Vertex1.x3, cells[cell].Vertex2.x3);
       min->SetVariableLimits(3, cells[cell].Vertex1.x4, cells[cell].Vertex2.x4);
       min->Minimize();
       xsec = min->MinValue();
       if (xsec < min_xsec)
         min_xsec = xsec;
       const double *xs = min->X();
       Vertex minv(xs[0], xs[1], xs[2], xs[3]);
       if (minv == cells[cell].Vertex1 || minv == cells[cell].Vertex2)
          minv = Vertex (x1m, x2m, x3m, x4m);
       if (dep < fMaxDepth - 1)
         for (int i = 0; i < 16; i++)
         {
            int child = 16*cell + i + 1;
            cells[child].Vertex1 = minv;
            cells[child].Vertex2 = Vertex ((i>>0)%2?cells[cell].Vertex1.x1:cells[cell].Vertex2.x1,
                                           (i>>1)%2?cells[cell].Vertex1.x2:cells[cell].Vertex2.x2,
                                           (i>>2)%2?cells[cell].Vertex1.x3:cells[cell].Vertex2.x3,
                                           (i>>3)%2?cells[cell].Vertex1.x4:cells[cell].Vertex2.x4);
         }
     }
  }
  Resonance_t res = genie::utils::res::FromString("P33(1232)");
  const InitialState & init_state = interaction -> InitState();
  double Enu = init_state.ProbeE(kRfHitNucRest);
  // other heuristic algorithm for maximum search to fix flaws of the first
  int N3 = 2;
  int N4 = 4;
  double x2max;
  if (Enu < 1.)
    x2max = 1.;
  else 
    x2max = 1./3;
  double dW = Wl.max - Wl.min;  
  double MR  = utils::res::Mass(res);
  double WR  = utils::res::Width(res);
  double x1 = (MR - Wl.min)/dW;
  double x1min = (MR - WR - Wl.min)/dW;
  if (x1min > 1)
  {
     delete f;
     return -min_xsec;
  }
  x1min = x1min<0?0:x1min;
  double x1max = (MR + WR - Wl.min)/dW;
  if (x1max < 0)
  {
     delete f;
     return -min_xsec;
  }
  x1max = x1max>1?1:x1max;
  if (x1 < x1min || x1 > x1max) x1=0.5*(x1min + x1max);
  for (int i3 = 0; i3 < N3; i3++)
  {
    double x3 = 1.*i3;
    double x3min = .5*i3;
    double x3max = .5*(i3 + 1);
    for (int i4 = 0; i4 <= N4; i4++)
    {
      double x4 = 1.*i4/N4;
      double x4min = 1.*i4/N4;
      double x4max = 1.*(i4 + 1)/N4;
      if (i4 == N4)
      {
        x4min = 3./N4;
        x4max = 1;
      }
      min->SetVariable(0, "x1", x1, step);
      min->SetVariable(1, "x2", 1./6, step);
      min->SetVariable(2, "x3", x3, step);
      min->SetVariable(3, "x4", x4, step);
      min->SetVariableLimits(0, x1min, x1max);
      min->SetVariableLimits(1, 0, x2max);
      min->SetVariableLimits(2, x3min, x3max);
      min->SetVariableLimits(3, x4min, x4max);
      min->Minimize();
      xsec = min->MinValue();
      if (xsec < min_xsec)
        min_xsec = xsec;
    }
  }  
  
  delete f;
 
  return -fSafetyFactor*min_xsec;
}

References e, fMaxDepth, genie::utils::res::FromString(), genie::KineGeneratorWithCache::fSafetyFactor, fWcut, genie::KineGeneratorWithCache::fXSecModel, genie::kRfHitNucRest, genie::utils::res::Mass(), genie::Range1D_t::max, genie::Range1D_t::min, genie::Interaction::PhaseSpacePtr(), genie::InitialState::ProbeE(), genie::utils::res::Width(), and genie::KPhaseSpace::WLim_SPP_iso().

Configure() [1/2]

void SPPEventGenerator::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 304 of file SPPEventGenerator.cxx.

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

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

Configure() [2/2]

void SPPEventGenerator::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 310 of file SPPEventGenerator.cxx.

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

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

GetFinalPionPdgCode()

int SPPEventGenerator::GetFinalPionPdgCode ( Interaction * interaction ) const

private

Definition at line 293 of file SPPEventGenerator.cxx.

{
   const XclsTag & xcls = interaction->ExclTag();
   if (xcls.NPiPlus() == 1)
     return kPdgPiP;
   else if (xcls.NPiMinus() == 1)
     return kPdgPiM;
   return kPdgPi0;
 
}

References genie::Interaction::ExclTag(), genie::kPdgPi0, genie::kPdgPiM, genie::kPdgPiP, genie::XclsTag::NPiMinus(), and genie::XclsTag::NPiPlus().

Referenced by ProcessEventRecord().

GetRecoilNucleonPdgCode()

int SPPEventGenerator::GetRecoilNucleonPdgCode ( Interaction * interaction ) const

private

Definition at line 283 of file SPPEventGenerator.cxx.

{
   const XclsTag & xcls = interaction->ExclTag();
   if (xcls.NProtons() == 1)
     return kPdgProton;
   else
     return kPdgNeutron;
 
}

References genie::Interaction::ExclTag(), genie::kPdgNeutron, genie::kPdgProton, and genie::XclsTag::NProtons().

Referenced by ProcessEventRecord().

LoadConfig()

void SPPEventGenerator::LoadConfig ( void )

private

Definition at line 316 of file SPPEventGenerator.cxx.

{
  
    // Safety factor for the maximum differential cross section
  this->GetParamDef("MaxXSec-SafetyFactor", fSafetyFactor, 1.03);
  this->GetParamDef("Maximum-Depth", fMaxDepth, 3);
 
  // Minimum energy for which max xsec would be cached, forcing explicit
  // calculation for lower eneries
  this->GetParamDef("Cache-MinEnergy", fEMin, 0.5);
 
 
  // Maximum allowed fractional cross section deviation from maxim cross
  // section used in rejection method
  this->GetParamDef("MaxXSec-DiffTolerance", fMaxXSecDiffTolerance, 999999.);
  assert(fMaxXSecDiffTolerance>=0);
 
  // Generate kinematics uniformly over allowed phase space and compute
  // an event weight?
  this->GetParamDef("UniformOverPhaseSpace", fGenerateUniformly, false);
  
  this->GetParamDef("Wcut", fWcut, -1.);
  
 
}

References genie::KineGeneratorWithCache::fEMin, genie::KineGeneratorWithCache::fGenerateUniformly, fMaxDepth, genie::KineGeneratorWithCache::fMaxXSecDiffTolerance, genie::KineGeneratorWithCache::fSafetyFactor, fWcut, and genie::Algorithm::GetParamDef().

Referenced by Configure(), and Configure().

ProcessEventRecord()

void SPPEventGenerator::ProcessEventRecord ( GHepRecord * event_rec ) const

virtual

Implements genie::EventRecordVisitorI.

Definition at line 64 of file SPPEventGenerator.cxx.

{
    
  
  LOG("SPPEventGen", pINFO) << "Generating resonance single pion production event kinematics...";
 
  if(fGenerateUniformly) {
    LOG("SPPEventGen", pNOTICE)
          << "Generating kinematics uniformly over the allowed phase space";
  }
  
  //-- Get the interaction from the GHEP record
  Interaction * interaction = evrec->Summary();
  const InitialState & init_state = interaction -> InitState();
  const KPhaseSpace& kps = interaction->PhaseSpace();
 
  // Access the target from the interaction summary
  //const Target & tgt = init_state.Tgt();
  Target * tgt = interaction -> InitStatePtr()->TgtPtr();
  
  // get masses of nucleon and pion
  PDGLibrary * pdglib = PDGLibrary::Instance();
  // imply isospin symmetry  
  double mpi  = (pdglib->Find(kPdgPiP)->Mass() + pdglib->Find(kPdgPi0)->Mass() + pdglib->Find(kPdgPiM)->Mass())/3;
  double mpi2 = mpi*mpi; 
  double M = (pdglib->Find(kPdgProton)->Mass() + pdglib->Find(kPdgNeutron)->Mass())/2;
  double M2  = M*M;
  // mass of final lepton
  double ml   = interaction->FSPrimLepton()->Mass();
  double ml2  = ml*ml;
  
  // 4-momentum of neutrino in lab frame
  TLorentzVector k1(*(init_state.GetProbeP4(kRfLab)));
  // 4-momentum of hit nucleon in lab frame
  TLorentzVector p1(*(evrec->HitNucleon())->P4());
  TLorentzVector p1_copy(p1);
  // set temporarily initial nucleon on shell
  p1.SetE(TMath::Sqrt(p1.P()*p1.P() + M*M));
  tgt->SetHitNucP4(p1);
  
  // neutrino 4-momentun in nucleon rest frame
  TLorentzVector k1_HNRF = k1;
  k1_HNRF.Boost(-p1.BoostVector());
  // neutrino energy in nucleon rest frame
  double Ev = k1_HNRF.E();
  // initial nucleon 4-momentun in nucleon rest frame
  TLorentzVector p1_HNRF(0,0,0,M);
  
  //-- Access cross section algorithm for running thread
  RunningThreadInfo * rtinfo = RunningThreadInfo::Instance();
  const EventGeneratorI * evg = rtinfo->RunningThread();
  fXSecModel = evg->CrossSectionAlg();
  
  // function gives differential cross section and depends on reduced variables W,Q2,cos(theta) and phi -> 1
  genie::utils::gsl::d4XSecMK_dWQ2CosThetaPhi_E * f   = new genie::utils::gsl::d4XSecMK_dWQ2CosThetaPhi_E(fXSecModel, interaction, fWcut);
  
  //-- Get the random number generators
  RandomGen * rnd = RandomGen::Instance();
 
  double xsec = -1;
  double xin[4];
  
  //-- For the subsequent kinematic selection with the rejection method:
  //   Calculate the max differential cross section or retrieve it from the
  //   cache. Throw an exception and quit the evg thread if a non-positive
  //   value is found.
  //   If the kinematics are generated uniformly over the allowed phase
  //   space the max xsec is irrelevant
  double xsec_max = (fGenerateUniformly) ? -1 : this->MaxXSec(evrec);
  // generate W, Q2, cos(theta) and phi by accept-reject method
  unsigned int iter = 0;
  bool accept = false;
  while(1) 
  {
     iter++;
     if(iter > 100*kRjMaxIterations) {
         LOG("SPPEventGen", pWARN)
              << "*** Could not select a valid kinematics variable after "
                                                    << iter << " iterations";
         evrec->EventFlags()->SetBitNumber(kKineGenErr, true);
         genie::exceptions::EVGThreadException exception;
         exception.SetReason("Couldn't select kinematics");
         exception.SwitchOnFastForward();
         throw exception;
     }
 
     xin[0] = rnd->RndKine().Rndm();
     xin[1] = rnd->RndKine().Rndm();
     xin[2] = rnd->RndKine().Rndm();
     xin[3] = rnd->RndKine().Rndm();
     
     
     //-- Computing cross section for the current kinematics
     xsec = -(*f)(xin);
     
     //-- Decide whether to accept the current kinematics
     if(!fGenerateUniformly)
     {
       this->AssertXSecLimits(interaction, xsec, xsec_max);
       double t = xsec_max * rnd->RndKine().Rndm();
       accept = (t < xsec);
     }
     else 
     {
        accept = (xsec>0);
     }
     
     // If the generated kinematics are accepted, finish-up module's job
     if(accept)
     {
       // reset 'trust' bits
       interaction->ResetBit(kISkipProcessChk);
       interaction->ResetBit(kISkipKinematicChk);
       break;
     }
     iter++;
   }
 
  // W,Q2,cos(theta) and phi from reduced variables
  Range1D_t Wl  = kps.WLim_SPP_iso();
  if (fWcut >= Wl.min)
    Wl.max = TMath::Min(fWcut,Wl.max);
  Range1D_t Q2l = kps.Q2Lim_W_SPP_iso();
  double W  = Wl.min + (Wl.max - Wl.min)*xin[0];
  interaction->KinePtr()->SetW(W);
  double Q2 = Q2l.min + (Q2l.max - Q2l.min)*xin[1];
  double CosTheta_isb = -1. + 2.*xin[2];
  double SinTheta_isb = (1 - CosTheta_isb*CosTheta_isb)<0?0:TMath::Sqrt(1 - CosTheta_isb*CosTheta_isb);
  double Phi_isb = 2*kPi*xin[3];
 
  
  // compute x,y for selected W,Q2
  double x=-1, y=-1;
  kinematics::WQ2toXY(Ev,M,W,Q2,x,y);
  
  if(fGenerateUniformly)
  {
    double vol     = (Wl.max-Wl.min)*(Q2l.max-Q2l.min)*4*kPi;
    double totxsec = evrec->XSec();
    double wght    = (vol/totxsec)*xsec;
    wght *= evrec->Weight();
    evrec->SetWeight(wght);
  }
 
 
  // set the cross section for the selected kinematics
  evrec->SetDiffXSec(xsec,kPSWQ2ctpphipfE);
 
  // lock selected kinematics & clear running values
  interaction->KinePtr()->SetQ2(Q2, true);
  interaction->KinePtr()->SetW (W,  true);
  interaction->KinePtr()->Setx (x,  true);
  interaction->KinePtr()->Sety (y,  true);
  interaction->KinePtr()->ClearRunningValues();
  
  
  double W2 = W*W;
  // Kinematical values of all participating particles in the isobaric frame
  double Enu_isb = (Ev*M - (ml2 + Q2)/2)/W;
  double El_isb  = (Ev*M - (ml2 + W2 - M2)/2)/W;
  double v_isb   = (W2 - M2 - Q2)/2/W;
  double q_isb   = TMath::Sqrt(v_isb*v_isb + Q2);
  double kz1_isb = 0.5*(q_isb+(Enu_isb*Enu_isb - El_isb*El_isb + ml2)/q_isb);
  double kz2_isb = kz1_isb - q_isb;
  double kx1_isb = (Enu_isb*Enu_isb - kz1_isb*kz1_isb)<0?0:TMath::Sqrt(Enu_isb*Enu_isb - kz1_isb*kz1_isb);
  double Epi_isb = (W2 + mpi2 - M2)/W/2;
  double ppi_isb = (Epi_isb - mpi)<0?0:TMath::Sqrt(Epi_isb*Epi_isb - mpi2);
  double E1_isb  = (W2 + Q2 + M2)/2/W;
  double E2_isb  = W - Epi_isb;
  
  // 4-momentum of all particles in the isobaric frame
  TLorentzVector k1_isb(kx1_isb, 0, kz1_isb, Enu_isb);
  TLorentzVector k2_isb(kx1_isb, 0, kz2_isb, El_isb);
  TLorentzVector p1_isb(0, 0, -q_isb, E1_isb);
  TLorentzVector p2_isb(-ppi_isb*SinTheta_isb*TMath::Cos(Phi_isb), -ppi_isb*SinTheta_isb*TMath::Sin(Phi_isb), -ppi_isb*CosTheta_isb, E2_isb);
  TLorentzVector pi_isb( ppi_isb*SinTheta_isb*TMath::Cos(Phi_isb),  ppi_isb*SinTheta_isb*TMath::Sin(Phi_isb),  ppi_isb*CosTheta_isb, Epi_isb);
  
  
  // boost from isobaric frame to hit nucleon rest frame
  TVector3 boost = -p1_isb.BoostVector();
  k1_isb.Boost(boost);
  k2_isb.Boost(boost);
  p2_isb.Boost(boost);
  pi_isb.Boost(boost);
 
  
  // rotation to align 3-momentum of all particles
  TVector3 rot_vect = k1_isb.Vect().Cross(k1_HNRF.Vect());
  double rot_angle =  k1_isb.Vect().Angle(k1_HNRF.Vect());
  k2_isb.Rotate(rot_angle, rot_vect);
  p2_isb.Rotate(rot_angle, rot_vect);
  pi_isb.Rotate(rot_angle, rot_vect);
 
  // boost to laboratory frame
  boost = p1.BoostVector();
  k2_isb.Boost(boost);
  p2_isb.Boost(boost);
  pi_isb.Boost(boost);
  
  
  tgt->SetHitNucP4(p1_copy);
 
  TLorentzVector x4l(*(evrec->Probe())->X4());
  // add final lepton
  evrec->AddParticle(interaction->FSPrimLeptonPdg(), kIStStableFinalState, evrec->ProbePosition(), -1, -1, -1, k2_isb, x4l);
  
  GHepStatus_t ist = (tgt->IsNucleus()) ? kIStHadronInTheNucleus : kIStStableFinalState;
  // add final nucleon
  evrec->AddParticle(this->GetRecoilNucleonPdgCode(interaction), ist, evrec->HitNucleonPosition(), -1, -1, -1, p2_isb, x4l);
  // add final pion
  evrec->AddParticle(this->GetFinalPionPdgCode(interaction), ist, evrec->HitNucleonPosition(), -1, -1, -1, pi_isb, x4l);
  
  delete f;
  
 
  return;
 
}

References genie::GHepRecord::AddParticle(), genie::KineGeneratorWithCache::AssertXSecLimits(), genie::Kinematics::ClearRunningValues(), genie::EventGeneratorI::CrossSectionAlg(), genie::GHepRecord::EventFlags(), genie::KineGeneratorWithCache::fGenerateUniformly, genie::PDGLibrary::Find(), genie::Interaction::FSPrimLepton(), genie::Interaction::FSPrimLeptonPdg(), fWcut, genie::KineGeneratorWithCache::fXSecModel, GetFinalPionPdgCode(), genie::InitialState::GetProbeP4(), GetRecoilNucleonPdgCode(), genie::GHepRecord::HitNucleon(), genie::GHepRecord::HitNucleonPosition(), genie::PDGLibrary::Instance(), genie::RandomGen::Instance(), genie::RunningThreadInfo::Instance(), genie::Target::IsNucleus(), genie::Interaction::KinePtr(), genie::kISkipKinematicChk, genie::kISkipProcessChk, genie::kIStHadronInTheNucleus, genie::kIStStableFinalState, genie::kKineGenErr, genie::kPdgNeutron, genie::kPdgPi0, genie::kPdgPiM, genie::kPdgPiP, genie::kPdgProton, genie::constants::kPi, genie::kPSWQ2ctpphipfE, genie::kRfLab, genie::controls::kRjMaxIterations, LOG, genie::Range1D_t::max, genie::KineGeneratorWithCache::MaxXSec(), genie::Range1D_t::min, genie::Interaction::PhaseSpace(), pINFO, pNOTICE, genie::GHepRecord::Probe(), genie::GHepRecord::ProbePosition(), pWARN, genie::KPhaseSpace::Q2Lim_W_SPP_iso(), genie::RandomGen::RndKine(), genie::RunningThreadInfo::RunningThread(), genie::GHepRecord::SetDiffXSec(), genie::Target::SetHitNucP4(), genie::Kinematics::SetQ2(), genie::exceptions::EVGThreadException::SetReason(), genie::Kinematics::SetW(), genie::GHepRecord::SetWeight(), genie::Kinematics::Setx(), genie::Kinematics::Sety(), genie::GHepRecord::Summary(), genie::exceptions::EVGThreadException::SwitchOnFastForward(), genie::GHepRecord::Weight(), genie::KPhaseSpace::WLim_SPP_iso(), genie::utils::kinematics::WQ2toXY(), and genie::GHepRecord::XSec().

Member Data Documentation

fMaxDepth

int genie::SPPEventGenerator::fMaxDepth

private

Maximum depth of dividing parent cell.

Definition at line 109 of file SPPEventGenerator.h.

Referenced by ComputeMaxXSec(), and LoadConfig().

fWcut

double genie::SPPEventGenerator::fWcut

private

Definition at line 70 of file SPPEventGenerator.h.

Referenced by ComputeMaxXSec(), LoadConfig(), and ProcessEventRecord().

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

• SPPEventGenerator.h
• SPPEventGenerator.cxx