EvtVectorIsr Class Reference

#include <EvtVectorIsr.hh>

Inheritance diagram for EvtVectorIsr:

Public Member Functions
	EvtVectorIsr ()
virtual	~EvtVectorIsr ()
void	getName (std::string &name)
EvtDecayBase *	clone ()
void	decay (EvtParticle *p)
void	init ()
void	initProbMax ()
Public Member Functions inherited from EvtDecayIncoherent
void	makeDecay (EvtParticle *p)
virtual	~EvtDecayIncoherent ()
void	setDaughterSpinDensity (int daughter)
int	isDaughterSpinDensitySet (int daughter)
Public Member Functions inherited from EvtDecayBase
virtual std::string	commandName ()
virtual void	command (std::string cmd)
double	getProbMax (double prob)
double	resetProbMax (double prob)
	EvtDecayBase ()
virtual	~EvtDecayBase ()
virtual bool	matchingDecay (const EvtDecayBase &other) const
EvtId	getParentId ()
double	getBranchingFraction ()
void	disableCheckQ ()
void	checkQ ()
int	getNDaug ()
EvtId *	getDaugs ()
EvtId	getDaug (int i)
int	getNArg ()
int	getPHOTOS ()
void	setPHOTOS ()
void	setVerbose ()
void	setSummary ()
double *	getArgs ()
std::string *	getArgsStr ()
double	getArg (int j)
std::string	getArgStr (int j)
std::string	getModelName ()
int	getDSum ()
int	summary ()
int	verbose ()
void	saveDecayInfo (EvtId ipar, int ndaug, EvtId *daug, int narg, std::vector< std::string > &args, std::string name, double brfr)
void	printSummary ()
void	setProbMax (double prbmx)
void	noProbMax ()
void	checkNArg (int a1, int a2=-1, int a3=-1, int a4=-1)
void	checkNDaug (int d1, int d2=-1)
void	checkSpinParent (EvtSpinType::spintype sp)
void	checkSpinDaughter (int d1, EvtSpinType::spintype sp)
virtual int	nRealDaughters ()

Additional Inherited Members
Static Public Member Functions inherited from EvtDecayBase
static void	findMasses (EvtParticle *p, int ndaugs, EvtId daugs[10], double masses[10])
static void	findMass (EvtParticle *p)
static double	findMaxMass (EvtParticle *p)
Protected Member Functions inherited from EvtDecayBase
bool	daugsDecayedByParentModel ()
Protected Attributes inherited from EvtDecayBase
bool	_daugsDecayedByParentModel

Detailed Description

Definition at line 30 of file EvtVectorIsr.hh.

Constructor & Destructor Documentation

EvtVectorIsr()

EvtVectorIsr::EvtVectorIsr ( )

inline

Definition at line 34 of file EvtVectorIsr.hh.

{}

Referenced by clone().

~EvtVectorIsr()

EvtVectorIsr::~EvtVectorIsr ( )

virtual

Definition at line 34 of file EvtVectorIsr.cc.

{}

Member Function Documentation

clone()

EvtDecayBase * EvtVectorIsr::clone ( )

virtual

Implements EvtDecayBase.

Definition at line 42 of file EvtVectorIsr.cc.

                                 {
 
  return new EvtVectorIsr;
 
}

decay()

void EvtVectorIsr::decay ( EvtParticle * p )

virtual

Implements EvtDecayBase.

Definition at line 72 of file EvtVectorIsr.cc.

                                        {
 
  EvtParticle *phi;
  EvtParticle *gamma;
 
  //the elctron mass
  double electMass=EvtPDL::getMeanMass(EvtPDL::getId("e-"));
 
 
  //get pointers to the daughters set
  //get masses/initial phase space - will overwrite the
  //p4s below to get the kinematic distributions correct
  p->initializePhaseSpace(getNDaug(),getDaugs());
  phi=p->getDaug(0);
  gamma=p->getDaug(1);
 
  double wcm=p->mass();
  double beta=2.*electMass/wcm; //electMass/Ebeam = betagamma
  beta=sqrt(1. - beta*beta);   //sqrt (1 - (m/ebeam)**2)
 
  //gamma momentum in the parents restframe
  double pg=(wcm*wcm-phi->mass()*phi->mass())/(2*wcm);
 
//    //generate kinematics according to Bonneau-Martin article
//    //Nucl. Phys. B27 (1971) 381-397
 
//    double y=pow((1+csmn)/(1-csmn),EvtRandom::Flat(0.0,1.0));
//    double cs=kcs*(y-1)/(y+1);
 
  // For backward compatibility with .dec files before SP5, the backward cos limit for
  //the ISR photon is actually given as *minus* the actual limit. Sorry, this wouldn't be
  //my choice.  -Joe
 
  double ymax=log((1.+beta*csfrmn)/(1.-beta*csfrmn));
  double ymin=log((1.-beta*csbkmn)/(1.+beta*csbkmn));
 
  // photon theta distributed as  2*beta/(1-beta**2*cos(theta)**2)
  double y=(ymax-ymin)*EvtRandom::Flat(0.0,1.0) + ymin;
  double cs=exp(y);
  cs=(cs - 1.)/(cs + 1.)/beta;
  double sn=sqrt(1-cs*cs);
 
  double fi=EvtRandom::Flat(EvtConst::twoPi);
 
  //four-vector for the phi
  EvtVector4R p4phi(sqrt(phi->mass()*phi->mass()+pg*pg),pg*sn*cos(fi),
         pg*sn*sin(fi),pg*cs);
 
  EvtVector4R p4gamma(pg,-p4phi.get(1),-p4phi.get(2),-p4phi.get(3));
 
  //save momenta for particles
  phi->init( getDaug(0),p4phi);
  gamma->init( getDaug(1),p4gamma);
 
  //try setting the spin density matrix of the phi
 
 
  //first get the polarization vectors of the gamma and phi
 
  EvtVector4C phi0=phi->epsParent(0);
  EvtVector4C phi1=phi->epsParent(1);
  EvtVector4C phi2=phi->epsParent(2);
 
  EvtVector4C gamma0=gamma->epsParentPhoton(0);
  EvtVector4C gamma1=gamma->epsParentPhoton(1);
 
  EvtComplex r1p=phi0*gamma0;
  EvtComplex r2p=phi1*gamma0;
  EvtComplex r3p=phi2*gamma0;
 
 
  EvtComplex r1m=phi0*gamma1;
  EvtComplex r2m=phi1*gamma1;
  EvtComplex r3m=phi2*gamma1;
 
  EvtComplex rho33=r3p*conj(r3p)+r3m*conj(r3m);
  EvtComplex rho22=r2p*conj(r2p)+r2m*conj(r2m);
  EvtComplex rho11=r1p*conj(r1p)+r1m*conj(r1m);
 
  EvtComplex rho13=r3p*conj(r1p)+r3m*conj(r1m);
  EvtComplex rho12=r2p*conj(r1p)+r2m*conj(r1m);
  EvtComplex rho23=r3p*conj(r2p)+r3m*conj(r2m);
 
  EvtComplex rho31=conj(rho13);
  EvtComplex rho32=conj(rho23);
  EvtComplex rho21=conj(rho12);
 
 
  EvtSpinDensity rho;
  rho.SetDim(3);
 
  rho.Set(0,0,rho11);
  rho.Set(0,1,rho12);
  rho.Set(0,2,rho13);
  rho.Set(1,0,rho21);
  rho.Set(1,1,rho22);
  rho.Set(1,2,rho23);
  rho.Set(2,0,rho31);
  rho.Set(2,1,rho32);
  rho.Set(2,2,rho33);
 
 
  setDaughterSpinDensity(0);
  phi->setSpinDensityForward(rho);
 
 
  return ;
}

getName()

void EvtVectorIsr::getName ( std::string & name )

virtual

Implements EvtDecayBase.

Definition at line 36 of file EvtVectorIsr.cc.

                                               {
 
  model_name="VECTORISR";     
 
}

init()

void EvtVectorIsr::init ( )

virtual

Reimplemented from EvtDecayBase.

Definition at line 48 of file EvtVectorIsr.cc.

                       {
 
  // check that there are 2 arguments
  checkNArg(2);
  checkNDaug(2);
 
  checkSpinParent(EvtSpinType::VECTOR);
  checkSpinDaughter(0,EvtSpinType::VECTOR);
  checkSpinDaughter(1,EvtSpinType::PHOTON);
 
  //copy the arguments into eaiser to remember names
 
  csfrmn=getArg(0);
  csbkmn=getArg(1);
 
 
}

initProbMax()

void EvtVectorIsr::initProbMax ( )

virtual

Reimplemented from EvtDecayBase.

Definition at line 66 of file EvtVectorIsr.cc.

                              {
 
  noProbMax();
 
}

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

• EvtVectorIsr.hh
• EvtVectorIsr.cc