Generates values for the kinematic variables describing neutrino-nucleus single kaon production events. Is a concrete implementation of the EventRecordVisitorI interface. More...

#include <SKKinematicsGenerator.h>

Inheritance diagram for genie::SKKinematicsGenerator:

Public Member Functions
	SKKinematicsGenerator ()

	SKKinematicsGenerator (string config)

	~SKKinematicsGenerator ()

void	ProcessEventRecord (GHepRecord *event_rec) const

void	Configure (const Registry &config)

void	Configure (string config)

void	LoadConfig (void)

void	CalculateKin_AtharSingleKaon (GHepRecord *event_rec) const

double	ComputeMaxXSec (const Interaction *in) const

double	Energy (const Interaction *in) 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...

Private Attributes
double	fMinLog1MinusCosTheta

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)

Protected Member Functions inherited from genie::KineGeneratorWithCache
	KineGeneratorWithCache ()

	KineGeneratorWithCache (string name)

	KineGeneratorWithCache (string name, string config)

	~KineGeneratorWithCache ()

virtual double	MaxXSec (GHepRecord *evrec) const

virtual double	FindMaxXSec (const Interaction *in) const

virtual void	CacheMaxXSec (const Interaction *in, double xsec) const

virtual CacheBranchFx *	AccessCacheBranch (const Interaction *in) 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. 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

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...

Protected Attributes inherited from genie::KineGeneratorWithCache
const XSecAlgorithmI *	fXSecModel

double	fSafetyFactor
	maxxsec -> maxxsec * safety_factor More...

double	fMaxXSecDiffTolerance
	max{100(xsec-maxxsec)/.5(xsec+maxxsec)} if xsec>maxxsec More...

double	fEMin
	min E for which maxxsec is cached - forcing explicit calc. More...

bool	fGenerateUniformly
	uniform over allowed phase space + event weight? 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...

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

Detailed Description

Generates values for the kinematic variables describing neutrino-nucleus single kaon production events. Is a concrete implementation of the EventRecordVisitorI interface.

Author: Chris Marshall <marshall pas.rochester.edu> University of Rochester

October 03, 2014

Definition at line 28 of file SKKinematicsGenerator.h.

Constructor & Destructor Documentation

SKKinematicsGenerator::SKKinematicsGenerator ( )

Definition at line 42 of file SKKinematicsGenerator.cxx.

                                              :
 KineGeneratorWithCache("genie::SKKinematicsGenerator")
 {
   //fEnvelope = 0;
 }

SKKinematicsGenerator::SKKinematicsGenerator ( string config )

Definition at line 48 of file SKKinematicsGenerator.cxx.

                                                           :
 KineGeneratorWithCache("genie::SKKinematicsGenerator", config)
 {
   //fEnvelope = 0;
 }

SKKinematicsGenerator::~SKKinematicsGenerator ( )

Definition at line 54 of file SKKinematicsGenerator.cxx.

 {
   //if(fEnvelope) delete fEnvelope;
 }

Member Function Documentation

void SKKinematicsGenerator::CalculateKin_AtharSingleKaon ( GHepRecord * event_rec ) const

Definition at line 73 of file SKKinematicsGenerator.cxx.

 {
   // Get the Primary Interacton object
   Interaction * interaction = evrec->Summary();
   interaction->SetBit(kISkipProcessChk);
   interaction->SetBit(kISkipKinematicChk);
 
   // Initialise a random number generator
   RandomGen * rnd = RandomGen::Instance();
 
   //-- 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);
 
   // Determine lepton and kaon masses
   int leppdg = interaction->FSPrimLeptonPdg();
   const TLorentzVector pnuc4 = interaction->InitState().Tgt().HitNucP4(); // 4-momentum of struck nucleon in lab frame
   TVector3 beta = pnuc4.BoostVector();
   TLorentzVector P4_nu = *(interaction->InitStatePtr()->GetProbeP4(kRfHitNucRest)); // struck nucleon rest frame
 
   double enu = P4_nu.E(); // in nucleon rest frame
   int kaon_pdgc = interaction->ExclTag().StrangeHadronPdg();
   double mk = PDGLibrary::Instance()->Find(kaon_pdgc)->Mass();
   double ml = PDGLibrary::Instance()->Find(leppdg)->Mass();
 
   // Maximum possible kinetic energy
   const double Tkmax = enu - mk - ml;
   const double Tlmax = enu - mk - ml;
 
   // Tkmax <= 0 means we are below threshold for sure
   if( Tkmax <= 0.0 ) {
     LOG("SKKinematics", pWARN) << "No available phase space";
     evrec->EventFlags()->SetBitNumber(kKineGenErr, true);
     genie::exceptions::EVGThreadException exception;
     exception.SetReason("No available phase space");
     exception.SwitchOnFastForward();
     throw exception;
   }
 
   const double Tkmin = 0.0;
   const double Tlmin = 0.0;
   // for performance, use log( 1 - cos(theta_lepton) ) instead of cos(theta_lepton) because it is sharply peaked near 1.0
   const double xmin = fMinLog1MinusCosTheta; // set in LoadConfig
   const double xmax =  0.69314718056; // log(2) is physical boundary
   const double phikqmin = 0.0;
   const double phikqmax = 2.0 * kPi;
   const double dtk = Tkmax - Tkmin;
   const double dtl = Tlmax - Tlmin;
   const double dx = xmax - xmin;
   const double dphikq = phikqmax - phikqmin;
 
   //------ Try to select a valid tk, tl, costhetal, phikq quadruplet
 
   unsigned int iter = 0;
   bool accept = false;
   double xsec      = -1; // diff XS
   double tk        = -1; // kaon kinetic energy
   double tl        = -1; // lepton kinetic energy
   double costhetal = -1; // cosine of lepton angle
   double phikq     = -1; // azimuthal angle between kaon and q vector
 
   while(1) {
      iter++;
      if(iter > kRjMaxIterations) {
         LOG("SKKinematics", pWARN)
              << "*** Could not select a valid (tk, tl, costhetal) triplet after "
                                                << iter << " iterations";
         evrec->EventFlags()->SetBitNumber(kKineGenErr, true);
         genie::exceptions::EVGThreadException exception;
         exception.SetReason("Couldn't select kinematics");
         exception.SwitchOnFastForward();
         throw exception;
      }
 
      if(fGenerateUniformly) {
        tk = Tkmin + dtk * rnd->RndKine().Rndm();
        tl = Tlmin + dtl * rnd->RndKine().Rndm();
        double x = xmin + dx * rnd->RndKine().Rndm(); // log(1-costheta)
        costhetal = 1.0 - TMath::Exp(x);
        phikq = phikqmin + dphikq * rnd->RndKine().Rndm();
      } else {
        tk = Tkmin + dtk * rnd->RndKine().Rndm();
        tl = Tlmin + dtl * rnd->RndKine().Rndm();
        double x = xmin + dx * rnd->RndKine().Rndm(); // log(1-costheta)
        costhetal = 1.0 - TMath::Exp(x);
        phikq = phikqmin + dphikq * rnd->RndKine().Rndm();
      }
 
      LOG("SKKinematics", pDEBUG) << "Trying: Tk = " << tk << ", Tl = " << tl << ", cosThetal = " << costhetal << ", phikq = " << phikq;
 
      // nucleon rest frame! these need to be boosted to the lab frame before they become actual particles
      interaction->KinePtr()->SetKV(kKVTk, tk);
      interaction->KinePtr()->SetKV(kKVTl, tl);
      interaction->KinePtr()->SetKV(kKVctl, costhetal);
      interaction->KinePtr()->SetKV(kKVphikq, phikq);
 
      // lorentz invariant stuff, but do all the calculations in the nucleon rest frame
      double el = tl + ml;
      double pl = TMath::Sqrt(el*el - ml*ml);
      double M = interaction->InitState().Tgt().Mass();
      TVector3 lepton_3vector = TVector3(0,0,0);
      lepton_3vector.SetMagThetaPhi(pl,TMath::ACos(costhetal),0.0);
      TLorentzVector P4_lep( lepton_3vector, tl+ml );
      TLorentzVector q = P4_nu - P4_lep;
      double Q2 = -q.Mag2();
      double xbj = Q2/(2*M*q.E());
      double y = q.E()/P4_nu.E();
      double W2 = (pnuc4+q).Mag2();
 
 
      // computing cross section for the current kinematics
      xsec = fXSecModel->XSec(interaction, kPSTkTlctl);
 
      //-- decide whether to accept the current kinematics
      if(!fGenerateUniformly) {
         // Jacobian is 1-costheta for x = log(1-costheta)
         double max = xsec_max;
         double t   = max * rnd->RndKine().Rndm();
         double J   = TMath::Abs(1. - costhetal);
 
         this->AssertXSecLimits(interaction, xsec*J, max);
 
         if( xsec*J > xsec_max ) { // freak out if this happens
           LOG("SKKinematics", pWARN)
              << "!!!!!!XSEC ABOVE MAX!!!!! xsec= " << xsec << ", J= " << J << ", xsec*J = " << xsec*J << " max= " << xsec_max;
         }
 
         accept = (t< J*xsec);
      }
      else {
         accept = (xsec>0);
      }
 
      //-- If the generated kinematics are accepted, finish-up module's job
      if(accept) {
 
         // calculate the stuff
 
         // for uniform kinematics, compute an event weight as
         // wght = (phase space volume)*(differential xsec)/(event total xsec)
         if(fGenerateUniformly) {
           double wght = 1.0; // change this
           wght *= evrec->Weight();
           LOG("SKKinematics", pNOTICE) << "Current event wght = " << wght;
           evrec->SetWeight(wght);
         }
         LOG("SKKinematics", pWARN) << "\nLepton energy (rest frame) = " << el << " kaon = " << tl + mk;
 
         // reset bits
         interaction->ResetBit(kISkipProcessChk);
         interaction->ResetBit(kISkipKinematicChk);
 
         interaction->KinePtr()->SetKV(kKVSelTk, tk); // nucleon rest frame
         interaction->KinePtr()->SetKV(kKVSelTl, tl); // nucleon rest frame
         interaction->KinePtr()->SetKV(kKVSelctl, costhetal); // nucleon rest frame
         interaction->KinePtr()->SetKV(kKVSelphikq, phikq); // nucleon rest frame
         interaction->KinePtr()->SetQ2(Q2, true);
         interaction->KinePtr()->SetW(TMath::Sqrt(W2), true);
         interaction->KinePtr()->Setx( xbj, true );
         interaction->KinePtr()->Sety( y, true );
         interaction->KinePtr()->ClearRunningValues();
 
         // set the cross section for the selected kinematics
         evrec->SetDiffXSec(xsec*(1.0-costhetal),kPSTkTlctl); // phase space is really log(1-costheta)
 
         return;
      }
   }// iterations
 }

double SKKinematicsGenerator::ComputeMaxXSec ( const Interaction * in ) const

virtual

Implements genie::KineGeneratorWithCache.

Definition at line 247 of file SKKinematicsGenerator.cxx.

 {
 // Computes the maximum differential cross section in the requested phase
 // space. This method overloads KineGeneratorWithCache::ComputeMaxXSec
 // method and the value is cached at a circular cache branch for retrieval
 // during subsequent event generation.
 
 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
   SLOG("SKKinematics", pDEBUG)
           << "Scanning the allowed phase space {K} for the max(dxsec/d{K})";
 #endif
 
   double max_xsec = 0;
   double max_tk = -1;
   double max_tl = -1;
   double max_ctl = -1;
 
   const int Ntk = 100;
   const int Ntl = 100;
   const int Nctl = 100;
   // don't do phi_kq -- the maximum will always occur at phi_kq = pi
 
   int leppdg = in->FSPrimLeptonPdg();
   double enu = in->InitState().ProbeE(kRfHitNucRest); // Enu in nucleon rest frame
   int kaon_pdgc = in->ExclTag().StrangeHadronPdg();
   double mk = PDGLibrary::Instance()->Find(kaon_pdgc)->Mass();
   double ml = PDGLibrary::Instance()->Find(leppdg)->Mass();
 
   const double Tkmax = enu - mk - ml;
   const double Tlmax = enu - mk - ml;
   const double Tkmin = 0.0;
   const double Tlmin = 0.0;
   // cross section is sharply peaked at forward lepton
   // faster to scan over log(1 - cos(theta)) = x
   const double xmin = fMinLog1MinusCosTheta; // set in LoadConfig
   const double xmax =  0.69314718056; // physical limit -- this is log(2)
   const double dtk = (Tkmax - Tkmin)/Ntk;
   const double dtl = (Tlmax - Tlmin)/Ntl;
   const double dx = (xmax - xmin)/Nctl;
 
   // XS is 0 when the kinetic energies are == 0, so start at 1
   for(int i = 1; i < Ntk; i++) {
     double tk = Tkmin + dtk*i;
     for(int j = 1; j < Ntl; j++) {
       double tl = Tlmin + dtl*j;
       for(int k = 0; k < Nctl; k++) {
         double log_1_minus_cosine_theta_lepton = xmin + dx*k;
         // XS takes cos(theta_lepton), we are scanning over log(1-that) to save time, convert to cos(theta_lepton) here
         double ctl = 1.0 - TMath::Exp(log_1_minus_cosine_theta_lepton);
 
         // The cross section is 4D, but the maximum differential cross section always occurs at phi_kq = pi (or -pi)
         // this is because there is more phase space for the kaon when it is opposite the lepton
         // to save time in this loop, just set phi_kq to pi
         double phikq = kPi;
 
         in->KinePtr()->SetKV(kKVTk, tk);
         in->KinePtr()->SetKV(kKVTl, tl);
         in->KinePtr()->SetKV(kKVctl, ctl);
         in->KinePtr()->SetKV(kKVphikq, phikq);
 
         double xsec = fXSecModel->XSec(in, kPSTkTlctl);
 
         // xsec returned by model is d4sigma/(dtk dtl dcosthetal dphikq)
         // convert lepton theta to log(1-costheta) by multiplying by jacobian 1 - costheta
         xsec *= (1.0 - ctl);
 
         if( xsec > max_xsec ) {
           max_xsec = xsec;
           max_tk = tk;
           max_tl = tl;
           max_ctl = ctl;
         }
       }//ctl
     }//tl
   }//tk
 
   LOG("SKKinematics", pINFO) << "Max XSec is " << max_xsec << " for enu = " << enu << " tk = " << max_tk << " tl = " << max_tl << " cosine theta = " << max_ctl;
 
   // Apply safety factor, since value retrieved from the cache might
   // correspond to a slightly different energy.
   max_xsec *= fSafetyFactor;
 
 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
   SLOG("SKKinematics", pDEBUG) << in->AsString();
   SLOG("SKKinematics", pDEBUG) << "Max xsec in phase space = " << max_xsec;
   SLOG("SKKinematics", pDEBUG) << "Computed using alg = " << fXSecModel->Id();
 #endif
 
 
 
   return max_xsec;
 }

void SKKinematicsGenerator::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 351 of file SKKinematicsGenerator.cxx.

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

void SKKinematicsGenerator::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 357 of file SKKinematicsGenerator.cxx.

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

double SKKinematicsGenerator::Energy ( const Interaction * in ) const

virtual

Reimplemented from genie::KineGeneratorWithCache.

Definition at line 341 of file SKKinematicsGenerator.cxx.

 {
 // Override the base class Energy() method to cache the max xsec for the
 // neutrino energy in the LAB rather than in the hit nucleon rest frame.
 
   const InitialState & init_state = interaction->InitState();
   double E = init_state.ProbeE(kRfLab);
   return E;
 }

void SKKinematicsGenerator::LoadConfig ( void )

Definition at line 363 of file SKKinematicsGenerator.cxx.

 {
   // max xsec safety factor (for rejection method) and min cached energy
   this->GetParamDef("MaxXSec-SafetyFactor", fSafetyFactor, 1.5);
   this->GetParamDef("Cache-MinEnergy",      fEMin,         0.6);
 
   // Generate kinematics uniformly over allowed phase space and compute
   // an event weight?
   this->GetParamDef("UniformOverPhaseSpace", fGenerateUniformly, false);
 
   // Maximum allowed fractional cross section deviation from maxim cross
   // section used in rejection method
   this->GetParamDef("MaxXSec-DiffTolerance", fMaxXSecDiffTolerance, 999999.);
   assert(fMaxXSecDiffTolerance>=0);
 
   //
   this->GetParamDef("MaxXSec-MinLog1MinusCosTheta", fMinLog1MinusCosTheta, -20.0);
 }

void SKKinematicsGenerator::ProcessEventRecord ( GHepRecord * event_rec ) const

virtual

Implements genie::EventRecordVisitorI.

Definition at line 59 of file SKKinematicsGenerator.cxx.

 {
   if(fGenerateUniformly) {
     LOG("SKKinematics", pNOTICE)
           << "Generating kinematics uniformly over the allowed phase space";
   }
 
   //-- Access cross section algorithm for running thread
   RunningThreadInfo * rtinfo = RunningThreadInfo::Instance();
   const EventGeneratorI * evg = rtinfo->RunningThread();
   fXSecModel = evg->CrossSectionAlg();
   CalculateKin_AtharSingleKaon(evrec);
 }

Member Data Documentation

double genie::SKKinematicsGenerator::fMinLog1MinusCosTheta

private

Definition at line 58 of file SKKinematicsGenerator.h.

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

Generator/src/Physics/Strange/EventGen/SKKinematicsGenerator.h
Generator/src/Physics/Strange/EventGen/SKKinematicsGenerator.cxx

Public Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation