[u/mrichter/AliRoot.git] / TUHKMgen / UHKM / HadronDecayer.cxx

/*

       July 2008 BW mass is limited by "PYTHIA method", by I. Lokhtin and L. Malinina
                                                                            
                                                                            
        Nikolai Amelin, Ludmila Malinina, Timur Pocheptsov (C) JINR/Dubna
      amelin@sunhe.jinr.ru, malinina@sunhe.jinr.ru, pocheptsov@sunhe.jinr.ru 
                           November. 2, 2005                                

*/

#include <functional>
#include <algorithm>
#include <vector>
#include <iostream>
#include <TRandom.h>
#include <TError.h>
#include <TMath.h>

#ifndef DATABASEPDG_H
#include "DatabasePDG.h"
#endif
#ifndef PARTICLE_PDG
#include "ParticlePDG.h"
#endif
#ifndef DECAY_CHANNEL
#include "DecayChannel.h"
#endif
#ifndef HADRONDECAYER_INCLUDED
#include "HadronDecayer.h"
#endif
#ifndef UKUTILITY_INCLUDED
#include "UKUtility.h"
#endif
#ifndef PARTICLE_INCLUDED
#include "Particle.h"
#endif
#include "HYJET_COMMONS.h"

//calculates decay time in fm/c
//calculates 1,2 and 3 body decays

using std::cout;
using std::endl;

Double_t GetDecayTime(const Particle &parent, Double_t weakDecayLimit) {
  ParticlePDG *pDef = parent.Def(); 
  Double_t width = pDef->GetWidth(); //GeV

  // if particle is set to be stable then return 0
  if(pDef->GetStableStatus())
    return 0.;

  if(width > weakDecayLimit && weakDecayLimit>=0.0) {
    const Double_t slope =  parent.E() * 0.1973 / (pDef->GetMass() * width);
    return -slope * TMath::Log(gRandom->Rndm());//in fm/c
  }

  return 0.;
}


extern "C" void mydelta_();
extern SERVICEEVCommon SERVICEEV;

void Decay(List_t &output, Particle &parent, ParticleAllocator &allocator, DatabasePDG* database) {

  // Get the PDG properties of the particle
  ParticlePDG *pDef = parent.Def();

  // Get the number of posible decay channels
  Int_t nDecayChannel = pDef->GetNDecayChannels();

  // check the full branching of this specie
  Double_t fullBranching = pDef->GetFullBranching(); // Only 3 or less body decays

  // return if particle has no branching
  if(fullBranching < 0.00001)
    return;

  // get the PDG mass of the specie  
  Double_t PDGmass = pDef->GetMass();
  Int_t ComprCodePyth=0;
  Float_t Delta =0;

  Bool_t success = kFALSE;
  Int_t iterations = 0;
  // Try to decay the particle
  while(!success) {
    //    std::cout << "HadronDecayer::Decay() iteration #" << iterations << std::endl;
    if(iterations>1000) {
      std::cout << "HadronDecayer::Decay() more than 1000 iterations to decay particle with code " 
		<< pDef->GetPDG() << std::endl;
      std::cout << "               Will be left undecayed ... check it out!" << std::endl;
      return;
    }
    
    // get a random mass using the Breit Wigner distribution 
    Double_t BWmass = gRandom->BreitWigner(PDGmass, pDef->GetWidth());     
    //      BWmass = PDGmass;
    // Try to cut the Breit Wigner tail of the particle using the cuts from pythia
    // The Delta variable is obtained from pythia based on the specie
    int encoding =pDef->GetPDG();
    SERVICEEV.ipdg = encoding;
    mydelta_();      
    ComprCodePyth=SERVICEEV.KC;
    Delta = SERVICEEV.delta;// PYDAT2.PMAS[KC][3];

    //if there are no such particle in PYTHIA particle table, we take Delta=0.4
    if(ComprCodePyth==0){
      BWmass=PDGmass; 
      Delta=0.0;
    } 

    //bad delta - an exception
    if(ComprCodePyth==254){
      BWmass=PDGmass; 
      Delta=0.0;
    } 
      
    // K0 decay into K0s or K0l
    if(TMath::Abs(encoding)==311) {
      BWmass=PDGmass;
      Delta=0.0;
    }

    //for particles from PYTHIA table only, if the BW mass is outside the cut range then quit this iteration and generate another BW mass
    if(ComprCodePyth!=0 && Delta>0 && (BWmass<PDGmass-Delta || BWmass>PDGmass+Delta)){
      iterations++;
      continue;
    }    
    
    // check how many decay channels are allowed with the generated mass
    Int_t nAllowedChannels = database->GetNAllowedChannels(pDef, BWmass);
    // if no decay channels are posible with this mass, then generate another BW mass
    if(nAllowedChannels==0) {    
      iterations++;
            std::cout << "HadronDecayer::Decay() no decays allowed at this BW mass" << std::endl;
      continue;
    }

    std::vector<Particle> apDaughter;
    std::vector<Double_t> dMass; //daughters'mass
    std::vector<Double_t> dMom;
    std::vector<Double_t> sm;
    std::vector<Double_t> rd;

    // we need to choose an allowed decay channel
    Double_t randValue = gRandom->Rndm() * fullBranching;
    Int_t chosenChannel = 1000;
    Bool_t found = kFALSE;
    Int_t channelIterations = 0;
    while(!found) {
      for(Int_t nChannel = 0; nChannel < nDecayChannel; nChannel++) {
	randValue -= pDef->GetDecayChannel(nChannel)->GetBranching();
	if(randValue <= 0. && database->IsChannelAllowed(pDef->GetDecayChannel(nChannel), BWmass)) {
	  chosenChannel = nChannel;
	  found = kTRUE;
	  break;
	}
      }
      channelIterations++;
    }

    // get the PDG information for the chosen decay channel
    DecayChannel *dc = pDef->GetDecayChannel(chosenChannel);
    Int_t nSec = dc->GetNDaughters();

    // Adjust the parent momentum four-vector for the MC generated Breit-Wigner mass
    Particle parentBW(database->GetPDGParticle(parent.Encoding()));
    parentBW.Pos(parent.Pos());
    Double_t BWenergy = TMath::Sqrt(parent.Mom().X()*parent.Mom().X() + 
				    parent.Mom().Y()*parent.Mom().Y() +
				    parent.Mom().Z()*parent.Mom().Z() +
				    BWmass*BWmass);

    Int_t NB = (Int_t)parent.GetType(); //particle from jets

    TLorentzVector MomparentBW(parent.Mom().X(), parent.Mom().Y(), parent.Mom().Z(), BWenergy); 
    parentBW.Mom(MomparentBW);
    // take into account BW when calculating boost velocity (for wide resonances it matters)
    TVector3 velocityBW(parentBW.Mom().BoostVector());

    // now we have an allowed decay
    // first case: one daughter particle
    if(nSec == 1) {
      // initialize the daughter particle
      Particle p1(database->GetPDGParticle(dc->GetDaughterPDG(0)));
      p1.Pos(parentBW.Pos());
      p1.Mom(parent.Mom());
      p1.SetLastMotherPdg(parentBW.Encoding());
      p1.SetLastMotherDecayCoor(parentBW.Pos());
      p1.SetLastMotherDecayMom(parentBW.Mom());
      p1.SetType(NB);

      // add the daughter to the list of secondaries
      Int_t parentIndex = parent.GetIndex();
      Int_t p1Index = p1.SetIndex();                           // set the daughter index
      p1.SetMother(parentIndex);                               // set the mother index for this daughter 
      parent.SetFirstDaughterIndex(p1Index);
      parent.SetLastDaughterIndex(p1Index);
      allocator.AddParticle(p1, output);
      success = kTRUE;  
    }
    // second case: two daughter particles
    else if(nSec == 2) {
      // initialize the daughter particles
      Particle p1(database->GetPDGParticle(dc->GetDaughterPDG(0)));
      p1.Pos(parentBW.Pos());
      Particle p2(database->GetPDGParticle(dc->GetDaughterPDG(1)));
      p2.Pos(parentBW.Pos());
      
      // calculate the momenta in rest frame of mother for the two particles (theta and phi are isotropic)
      MomAntiMom(p1.Mom(), p1.TableMass(), p2.Mom(), p2.TableMass(), BWmass);
    
      // boost to the laboratory system (to the mother velocity)
      p1.Mom().Boost(velocityBW);
      p2.Mom().Boost(velocityBW);

      //store information about mother
      p1.SetLastMotherPdg(parentBW.Encoding());
      p1.SetLastMotherDecayCoor(parentBW.Pos());
      p1.SetLastMotherDecayMom(parentBW.Mom());
      p2.SetLastMotherPdg(parentBW.Encoding());
      p2.SetLastMotherDecayCoor(parentBW.Pos());
      p2.SetLastMotherDecayMom(parentBW.Mom());
      //set to daughters the same type as has mother
      p1.SetType(NB);
      p2.SetType(NB);


      // check the kinematics in the lab system
      Double_t deltaS = TMath::Sqrt((parentBW.Mom().X()-p1.Mom().X()-p2.Mom().X())*(parentBW.Mom().X()-p1.Mom().X()-p2.Mom().X())+
				    (parentBW.Mom().Y()-p1.Mom().Y()-p2.Mom().Y())*(parentBW.Mom().Y()-p1.Mom().Y()-p2.Mom().Y())+
				    (parentBW.Mom().Z()-p1.Mom().Z()-p2.Mom().Z())*(parentBW.Mom().Z()-p1.Mom().Z()-p2.Mom().Z())+
				    (parentBW.Mom().E()-p1.Mom().E()-p2.Mom().E())*(parentBW.Mom().E()-p1.Mom().E()-p2.Mom().E()));
      // if deltaS is too big then repeat the kinematic procedure
 
      if(deltaS>0.001) {
	iterations++;
	continue;
      }
      // push particles to the list of secondaries
      Int_t parentIndex = parent.GetIndex();
      p1.SetIndex(); 
      p2.SetIndex();
      p1.SetMother(parentIndex); 
      p2.SetMother(parentIndex);
      parent.SetFirstDaughterIndex(p1.GetIndex());
      parent.SetLastDaughterIndex(p2.GetIndex());
      allocator.AddParticle(p1, output);
      allocator.AddParticle(p2, output);
      success = kTRUE;
    
    }

    // third case: three daughter particle
    else if(nSec == 3) {
      // initialize the daughter particle
      Particle p1(database->GetPDGParticle(dc->GetDaughterPDG(0)));
      p1.Pos(parentBW.Pos());
      Particle p2(database->GetPDGParticle(dc->GetDaughterPDG(1)));
      p2.Pos(parentBW.Pos());
      Particle p3(database->GetPDGParticle(dc->GetDaughterPDG(2)));
      p3.Pos(parentBW.Pos());
      // calculate the momenta in the rest frame of the mother particle
      Double_t pAbs1 = 0., pAbs2 = 0., pAbs3 = 0., sumPabs = 0., maxPabs = 0.;
      Double_t mass1 = p1.TableMass(), mass2 = p2.TableMass(), mass3 = p3.TableMass();
      TLorentzVector &mom1 = p1.Mom(), &mom2 = p2.Mom(), &mom3 = p3.Mom(); 
      Double_t deltaMass = BWmass - mass1 - mass2 - mass3;

      do {
	Double_t rd1 = gRandom->Rndm();
	Double_t rd2 = gRandom->Rndm();
	if (rd2 > rd1)
	  std::swap(rd1, rd2);
	// 1
	Double_t e = rd2*deltaMass;
	pAbs1 = TMath::Sqrt(e*e + 2*e*mass1);
	sumPabs = pAbs1;
	maxPabs = sumPabs;
	// 2
	e = (1-rd1)*deltaMass;
	pAbs2 = TMath::Sqrt(e*e + 2*e*mass2);
	
	if(pAbs2 > maxPabs)
	  maxPabs = pAbs2;
	
	sumPabs += pAbs2;
	// 3
	e = (rd1-rd2)*deltaMass;
	pAbs3 = TMath::Sqrt(e*e + 2*e*mass3);
	
	if (pAbs3 > maxPabs)
	  maxPabs =  pAbs3;
	sumPabs  +=  pAbs3;
      } while(maxPabs > sumPabs - maxPabs);
      
      // isotropic sample first particle 3-momentum
      Double_t cosTheta = 2*(gRandom->Rndm()) - 1;
      Double_t sinTheta = TMath::Sqrt(1 - cosTheta*cosTheta);
      Double_t phi      = TMath::TwoPi()*(gRandom->Rndm());
      Double_t sinPhi   = TMath::Sin(phi);
      Double_t cosPhi   = TMath::Cos(phi);
      
      mom1.SetPxPyPzE(sinTheta*cosPhi, sinTheta*sinPhi, cosTheta, 0);
      mom1 *= pAbs1;
      // sample rest particle 3-momentum
      Double_t cosThetaN = (pAbs2*pAbs2 - pAbs3*pAbs3 - pAbs1*pAbs1)/(2*pAbs1*pAbs3);
      Double_t sinThetaN = TMath::Sqrt(1 - cosThetaN*cosThetaN);
      Double_t phiN      = TMath::TwoPi()*(gRandom->Rndm());
      Double_t sinPhiN   = TMath::Sin(phiN);
      Double_t cosPhiN   = TMath::Cos(phiN);
      
      mom3.SetPxPyPzE(sinThetaN*cosPhiN*cosTheta*cosPhi - sinThetaN*sinPhiN*sinPhi + cosThetaN*sinTheta*cosPhi,
		      sinThetaN*cosPhiN*cosTheta*sinPhi + sinThetaN*sinPhiN*cosPhi + cosThetaN*sinTheta*sinPhi,
		      -sinThetaN*cosPhiN*sinTheta + cosThetaN*cosTheta,
		      0.);
      
      mom3 *= pAbs3*mom3.P();
      mom2 = mom1;
      mom2 += mom3;
      mom2 *= -1.;
      // calculate energy
      mom1.SetE(TMath::Sqrt(mom1.P()*mom1.P() + mass1*mass1));
      mom2.SetE(TMath::Sqrt(mom2.P()*mom2.P() + mass2*mass2));
      mom3.SetE(TMath::Sqrt(mom3.P()*mom3.P() + mass3*mass3));
      
      // boost to Lab system
      mom1.Boost(velocityBW);
      mom2.Boost(velocityBW);
      mom3.Boost(velocityBW);
      
      p1.SetLastMotherPdg(parentBW.Encoding());
      p1.SetLastMotherDecayCoor(parentBW.Pos());
      p1.SetLastMotherDecayMom(parentBW.Mom());
      p2.SetLastMotherPdg(parentBW.Encoding());
      p2.SetLastMotherDecayCoor(parentBW.Pos());
      p2.SetLastMotherDecayMom(parentBW.Mom());
      p3.SetLastMotherPdg(parentBW.Encoding());
      p3.SetLastMotherDecayCoor(parentBW.Pos());
      p3.SetLastMotherDecayMom(parentBW.Mom());

      //set to daughters the same type as has mother  
      p1.SetType(NB);
      p2.SetType(NB);
      p3.SetType(NB);

      // energy conservation check in the lab system
      Double_t deltaS = TMath::Sqrt((parentBW.Mom().X()-p1.Mom().X()-p2.Mom().X()-p3.Mom().X())*(parentBW.Mom().X()-p1.Mom().X()-p2.Mom().X()-p3.Mom().X()) +
				    (parentBW.Mom().Y()-p1.Mom().Y()-p2.Mom().Y()-p3.Mom().Y())*(parentBW.Mom().Y()-p1.Mom().Y()-p2.Mom().Y()-p3.Mom().Y()) +
				    (parentBW.Mom().Z()-p1.Mom().Z()-p2.Mom().Z()-p3.Mom().Z())*(parentBW.Mom().Z()-p1.Mom().Z()-p2.Mom().Z()-p3.Mom().Z())	+
				    (parentBW.Mom().E()-p1.Mom().E()-p2.Mom().E()-p3.Mom().E())*(parentBW.Mom().E()-p1.Mom().E()-p2.Mom().E()-p3.Mom().E()));
      // if deltaS is too big then repeat the kinematic procedure
      if(deltaS>0.001) {
	//	cout << "3-body decay kinematic check in lab system: " << pDef->GetPDG() << " --> " << p1.Encoding() << " + " << p2.Encoding() << " + " << p3.Encoding() << endl;
	//	cout << "Mother    (e,px,py,pz): " << parentBW.Mom().E() << "\t" << parentBW.Mom().X() << "\t" << parentBW.Mom().Y() << "\t" << parentBW.Mom().Z() << endl;
	//	cout << "Daughter1 (e,px,py,pz): " << p1.Mom().E() << "\t" << p1.Mom().X() << "\t" << p1.Mom().Y() << "\t" << p1.Mom().Z() << endl;
	//	cout << "Daughter2 (e,px,py,pz): " << p2.Mom().E() << "\t" << p2.Mom().X() << "\t" << p2.Mom().Y() << "\t" << p2.Mom().Z() << endl;
	//	cout << "Daughter3 (e,px,py,pz): " << p3.Mom().E() << "\t" << p3.Mom().X() << "\t" << p3.Mom().Y() << "\t" << p3.Mom().Z() << endl;
	//	cout << "3-body decay delta(sqrtS) = " << deltaS << endl;
	//	cout << "Repeating the decay algorithm..." << endl;

	iterations++;
	continue;
      }

      Int_t parentIndex = parent.GetIndex();
      p1.SetIndex();
      p2.SetIndex();
      p3.SetIndex();
      p1.SetMother(parentIndex); 
      p2.SetMother(parentIndex);
      p3.SetMother(parentIndex);
      parent.SetFirstDaughterIndex(p1.GetIndex());
      parent.SetLastDaughterIndex(p3.GetIndex());
      allocator.AddParticle(p1, output);
      allocator.AddParticle(p2, output);
      allocator.AddParticle(p3, output);
      success = kTRUE;
    }
  }
  return;
}
Commit	Line	Data
b1c2e580	1	/*
	2
	3	July 2008 BW mass is limited by "PYTHIA method", by I. Lokhtin and L. Malinina
	4
	5
	6	Nikolai Amelin, Ludmila Malinina, Timur Pocheptsov (C) JINR/Dubna
	7	amelin@sunhe.jinr.ru, malinina@sunhe.jinr.ru, pocheptsov@sunhe.jinr.ru
	8	November. 2, 2005
	9
	10	*/
	11
	12	#include <functional>
	13	#include <algorithm>
	14	#include <vector>
	15	#include <iostream>
	16	#include <TRandom.h>
	17	#include <TError.h>
	18	#include <TMath.h>
	19
3fa37a65	20	#ifndef DATABASEPDG_H
b1c2e580	21	#include "DatabasePDG.h"
	22	#endif
	23	#ifndef PARTICLE_PDG
	24	#include "ParticlePDG.h"
	25	#endif
	26	#ifndef DECAY_CHANNEL
	27	#include "DecayChannel.h"
	28	#endif
	29	#ifndef HADRONDECAYER_INCLUDED
	30	#include "HadronDecayer.h"
	31	#endif
	32	#ifndef UKUTILITY_INCLUDED
	33	#include "UKUtility.h"
	34	#endif
	35	#ifndef PARTICLE_INCLUDED
	36	#include "Particle.h"
	37	#endif
	38	#include "HYJET_COMMONS.h"
	39
	40	//calculates decay time in fm/c
	41	//calculates 1,2 and 3 body decays
	42
	43	using std::cout;
	44	using std::endl;
	45
	46	Double_t GetDecayTime(const Particle &parent, Double_t weakDecayLimit) {
	47	ParticlePDG *pDef = parent.Def();
	48	Double_t width = pDef->GetWidth(); //GeV
7b7936e9	49
	50	// if particle is set to be stable then return 0
	51	if(pDef->GetStableStatus())
	52	return 0.;
	53
	54	if(width > weakDecayLimit && weakDecayLimit>=0.0) {
b1c2e580	55	const Double_t slope = parent.E() * 0.1973 / (pDef->GetMass() * width);
b1c2e580	56	return -slope * TMath::Log(gRandom->Rndm());//in fm/c
	57	}
	58
	59	return 0.;
	60	}
	61
	62
	63	extern "C" void mydelta_();
	64	extern SERVICEEVCommon SERVICEEV;
	65
	66	void Decay(List_t &output, Particle &parent, ParticleAllocator &allocator, DatabasePDG* database) {
b1c2e580	67
	68	// Get the PDG properties of the particle
	69	ParticlePDG *pDef = parent.Def();
	70
	71	// Get the number of posible decay channels
	72	Int_t nDecayChannel = pDef->GetNDecayChannels();
	73
	74	// check the full branching of this specie
	75	Double_t fullBranching = pDef->GetFullBranching(); // Only 3 or less body decays
	76
	77	// return if particle has no branching
	78	if(fullBranching < 0.00001)
	79	return;
	80
	81	// get the PDG mass of the specie
	82	Double_t PDGmass = pDef->GetMass();
3fa37a65	83	Int_t ComprCodePyth=0;
b1c2e580	84	Float_t Delta =0;
	85
	86	Bool_t success = kFALSE;
	87	Int_t iterations = 0;
	88	// Try to decay the particle
	89	while(!success) {
7b7936e9	90	// std::cout << "HadronDecayer::Decay() iteration #" << iterations << std::endl;
	91	if(iterations>1000) {
	92	std::cout << "HadronDecayer::Decay() more than 1000 iterations to decay particle with code "
	93	<< pDef->GetPDG() << std::endl;
	94	std::cout << " Will be left undecayed ... check it out!" << std::endl;
	95	return;
	96	}
3fa37a65	97
b1c2e580	98	// get a random mass using the Breit Wigner distribution
3fa37a65	99	Double_t BWmass = gRandom->BreitWigner(PDGmass, pDef->GetWidth());
b1c2e580	100	// BWmass = PDGmass;
	101	// Try to cut the Breit Wigner tail of the particle using the cuts from pythia
	102	// The Delta variable is obtained from pythia based on the specie
	103	int encoding =pDef->GetPDG();
	104	SERVICEEV.ipdg = encoding;
	105	mydelta_();
	106	ComprCodePyth=SERVICEEV.KC;
	107	Delta = SERVICEEV.delta;// PYDAT2.PMAS[KC][3];
	108
	109	//if there are no such particle in PYTHIA particle table, we take Delta=0.4
	110	if(ComprCodePyth==0){
	111	BWmass=PDGmass;
	112	Delta=0.0;
	113	}
	114
	115	//bad delta - an exception
	116	if(ComprCodePyth==254){
	117	BWmass=PDGmass;
	118	Delta=0.0;
	119	}
	120
7b7936e9	121	// K0 decay into K0s or K0l
	122	if(TMath::Abs(encoding)==311) {
	123	BWmass=PDGmass;
	124	Delta=0.0;
	125	}
	126
b1c2e580	127	//for particles from PYTHIA table only, if the BW mass is outside the cut range then quit this iteration and generate another BW mass
b1c2e580	128	if(ComprCodePyth!=0 && Delta>0 && (BWmass<PDGmass-Delta \|\| BWmass>PDGmass+Delta)){
7b7936e9	129	iterations++;
b1c2e580	130	continue;
b1c2e580	131	}
b1c2e580	132
	133	// check how many decay channels are allowed with the generated mass
	134	Int_t nAllowedChannels = database->GetNAllowedChannels(pDef, BWmass);
	135	// if no decay channels are posible with this mass, then generate another BW mass
	136	if(nAllowedChannels==0) {
	137	iterations++;
3fa37a65	138	std::cout << "HadronDecayer::Decay() no decays allowed at this BW mass" << std::endl;
b1c2e580	139	continue;
	140	}
	141
	142	std::vector<Particle> apDaughter;
	143	std::vector<Double_t> dMass; //daughters'mass
	144	std::vector<Double_t> dMom;
	145	std::vector<Double_t> sm;
	146	std::vector<Double_t> rd;
	147
	148	// we need to choose an allowed decay channel
	149	Double_t randValue = gRandom->Rndm() * fullBranching;
	150	Int_t chosenChannel = 1000;
	151	Bool_t found = kFALSE;
	152	Int_t channelIterations = 0;
	153	while(!found) {
3fa37a65	154	for(Int_t nChannel = 0; nChannel < nDecayChannel; nChannel++) {
b1c2e580	155	randValue -= pDef->GetDecayChannel(nChannel)->GetBranching();
	156	if(randValue <= 0. && database->IsChannelAllowed(pDef->GetDecayChannel(nChannel), BWmass)) {
	157	chosenChannel = nChannel;
	158	found = kTRUE;
	159	break;
	160	}
	161	}
	162	channelIterations++;
	163	}
	164
	165	// get the PDG information for the chosen decay channel
	166	DecayChannel *dc = pDef->GetDecayChannel(chosenChannel);
	167	Int_t nSec = dc->GetNDaughters();
	168
	169	// Adjust the parent momentum four-vector for the MC generated Breit-Wigner mass
	170	Particle parentBW(database->GetPDGParticle(parent.Encoding()));
	171	parentBW.Pos(parent.Pos());
	172	Double_t BWenergy = TMath::Sqrt(parent.Mom().X()*parent.Mom().X() +
	173	parent.Mom().Y()*parent.Mom().Y() +
	174	parent.Mom().Z()*parent.Mom().Z() +
	175	BWmass*BWmass);
	176
	177	Int_t NB = (Int_t)parent.GetType(); //particle from jets
	178
	179	TLorentzVector MomparentBW(parent.Mom().X(), parent.Mom().Y(), parent.Mom().Z(), BWenergy);
	180	parentBW.Mom(MomparentBW);
	181	// take into account BW when calculating boost velocity (for wide resonances it matters)
	182	TVector3 velocityBW(parentBW.Mom().BoostVector());
	183
	184	// now we have an allowed decay
	185	// first case: one daughter particle
	186	if(nSec == 1) {
	187	// initialize the daughter particle
	188	Particle p1(database->GetPDGParticle(dc->GetDaughterPDG(0)));
7b7936e9	189	p1.Pos(parentBW.Pos());
7b7936e9	190	p1.Mom(parent.Mom());
b1c2e580	191	p1.SetLastMotherPdg(parentBW.Encoding());
	192	p1.SetLastMotherDecayCoor(parentBW.Pos());
	193	p1.SetLastMotherDecayMom(parentBW.Mom());
7b7936e9	194	p1.SetType(NB);
b1c2e580	195
3fa37a65	196	// add the daughter to the list of secondaries
3fa37a65	197	Int_t parentIndex = parent.GetIndex();
b1c2e580	198	Int_t p1Index = p1.SetIndex(); // set the daughter index
b1c2e580	199	p1.SetMother(parentIndex); // set the mother index for this daughter
3fa37a65	200	parent.SetFirstDaughterIndex(p1Index);
3fa37a65	201	parent.SetLastDaughterIndex(p1Index);
b1c2e580	202	allocator.AddParticle(p1, output);
	203	success = kTRUE;
	204	}
	205	// second case: two daughter particles
	206	else if(nSec == 2) {
	207	// initialize the daughter particles
	208	Particle p1(database->GetPDGParticle(dc->GetDaughterPDG(0)));
	209	p1.Pos(parentBW.Pos());
	210	Particle p2(database->GetPDGParticle(dc->GetDaughterPDG(1)));
	211	p2.Pos(parentBW.Pos());
	212
	213	// calculate the momenta in rest frame of mother for the two particles (theta and phi are isotropic)
	214	MomAntiMom(p1.Mom(), p1.TableMass(), p2.Mom(), p2.TableMass(), BWmass);
	215
	216	// boost to the laboratory system (to the mother velocity)
	217	p1.Mom().Boost(velocityBW);
	218	p2.Mom().Boost(velocityBW);
	219
	220	//store information about mother
	221	p1.SetLastMotherPdg(parentBW.Encoding());
	222	p1.SetLastMotherDecayCoor(parentBW.Pos());
	223	p1.SetLastMotherDecayMom(parentBW.Mom());
	224	p2.SetLastMotherPdg(parentBW.Encoding());
	225	p2.SetLastMotherDecayCoor(parentBW.Pos());
	226	p2.SetLastMotherDecayMom(parentBW.Mom());
b1c2e580	227	//set to daughters the same type as has mother
	228	p1.SetType(NB);
	229	p2.SetType(NB);
	230
	231
	232	// check the kinematics in the lab system
	233	Double_t deltaS = TMath::Sqrt((parentBW.Mom().X()-p1.Mom().X()-p2.Mom().X())*(parentBW.Mom().X()-p1.Mom().X()-p2.Mom().X())+
	234	(parentBW.Mom().Y()-p1.Mom().Y()-p2.Mom().Y())*(parentBW.Mom().Y()-p1.Mom().Y()-p2.Mom().Y())+
	235	(parentBW.Mom().Z()-p1.Mom().Z()-p2.Mom().Z())*(parentBW.Mom().Z()-p1.Mom().Z()-p2.Mom().Z())+
	236	(parentBW.Mom().E()-p1.Mom().E()-p2.Mom().E())*(parentBW.Mom().E()-p1.Mom().E()-p2.Mom().E()));
	237	// if deltaS is too big then repeat the kinematic procedure
	238
b1c2e580	239	if(deltaS>0.001) {
b1c2e580	240	iterations++;
	241	continue;
	242	}
	243	// push particles to the list of secondaries
3fa37a65	244	Int_t parentIndex = parent.GetIndex();
b1c2e580	245	p1.SetIndex();
	246	p2.SetIndex();
	247	p1.SetMother(parentIndex);
	248	p2.SetMother(parentIndex);
3fa37a65	249	parent.SetFirstDaughterIndex(p1.GetIndex());
3fa37a65	250	parent.SetLastDaughterIndex(p2.GetIndex());
b1c2e580	251	allocator.AddParticle(p1, output);
	252	allocator.AddParticle(p2, output);
	253	success = kTRUE;
3fa37a65	254
b1c2e580	255	}
	256
	257	// third case: three daughter particle
	258	else if(nSec == 3) {
	259	// initialize the daughter particle
	260	Particle p1(database->GetPDGParticle(dc->GetDaughterPDG(0)));
	261	p1.Pos(parentBW.Pos());
	262	Particle p2(database->GetPDGParticle(dc->GetDaughterPDG(1)));
	263	p2.Pos(parentBW.Pos());
	264	Particle p3(database->GetPDGParticle(dc->GetDaughterPDG(2)));
	265	p3.Pos(parentBW.Pos());
	266	// calculate the momenta in the rest frame of the mother particle
	267	Double_t pAbs1 = 0., pAbs2 = 0., pAbs3 = 0., sumPabs = 0., maxPabs = 0.;
	268	Double_t mass1 = p1.TableMass(), mass2 = p2.TableMass(), mass3 = p3.TableMass();
	269	TLorentzVector &mom1 = p1.Mom(), &mom2 = p2.Mom(), &mom3 = p3.Mom();
	270	Double_t deltaMass = BWmass - mass1 - mass2 - mass3;
	271
	272	do {
	273	Double_t rd1 = gRandom->Rndm();
	274	Double_t rd2 = gRandom->Rndm();
	275	if (rd2 > rd1)
	276	std::swap(rd1, rd2);
	277	// 1
	278	Double_t e = rd2*deltaMass;
	279	pAbs1 = TMath::Sqrt(ee + 2e*mass1);
	280	sumPabs = pAbs1;
	281	maxPabs = sumPabs;
	282	// 2
	283	e = (1-rd1)*deltaMass;
	284	pAbs2 = TMath::Sqrt(ee + 2e*mass2);
	285
	286	if(pAbs2 > maxPabs)
	287	maxPabs = pAbs2;
	288
	289	sumPabs += pAbs2;
	290	// 3
	291	e = (rd1-rd2)*deltaMass;
	292	pAbs3 = TMath::Sqrt(ee + 2e*mass3);
	293
	294	if (pAbs3 > maxPabs)
	295	maxPabs = pAbs3;
	296	sumPabs += pAbs3;
	297	} while(maxPabs > sumPabs - maxPabs);
	298
	299	// isotropic sample first particle 3-momentum
	300	Double_t cosTheta = 2*(gRandom->Rndm()) - 1;
	301	Double_t sinTheta = TMath::Sqrt(1 - cosTheta*cosTheta);
	302	Double_t phi = TMath::TwoPi()*(gRandom->Rndm());
	303	Double_t sinPhi = TMath::Sin(phi);
	304	Double_t cosPhi = TMath::Cos(phi);
	305
	306	mom1.SetPxPyPzE(sinThetacosPhi, sinThetasinPhi, cosTheta, 0);
	307	mom1 *= pAbs1;
	308	// sample rest particle 3-momentum
	309	Double_t cosThetaN = (pAbs2pAbs2 - pAbs3pAbs3 - pAbs1pAbs1)/(2pAbs1*pAbs3);
	310	Double_t sinThetaN = TMath::Sqrt(1 - cosThetaN*cosThetaN);
	311	Double_t phiN = TMath::TwoPi()*(gRandom->Rndm());
	312	Double_t sinPhiN = TMath::Sin(phiN);
	313	Double_t cosPhiN = TMath::Cos(phiN);
	314
	315	mom3.SetPxPyPzE(sinThetaNcosPhiNcosThetacosPhi - sinThetaNsinPhiNsinPhi + cosThetaNsinTheta*cosPhi,
	316	sinThetaNcosPhiNcosThetasinPhi + sinThetaNsinPhiNcosPhi + cosThetaNsinTheta*sinPhi,
	317	-sinThetaNcosPhiNsinTheta + cosThetaN*cosTheta,
	318	0.);
319
320	mom3 = pAbs3mom3.P();
321	mom2 = mom1;
322	mom2 += mom3;
323	mom2 *= -1.;
324	// calculate energy
325	mom1.SetE(TMath::Sqrt(mom1.P()mom1.P() + mass1mass1));
326	mom2.SetE(TMath::Sqrt(mom2.P()mom2.P() + mass2mass2));
327	mom3.SetE(TMath::Sqrt(mom3.P()mom3.P() + mass3mass3));
328
329	// boost to Lab system
330	mom1.Boost(velocityBW);
331	mom2.Boost(velocityBW);
332	mom3.Boost(velocityBW);
333
334	p1.SetLastMotherPdg(parentBW.Encoding());
335	p1.SetLastMotherDecayCoor(parentBW.Pos());
336	p1.SetLastMotherDecayMom(parentBW.Mom());
337	p2.SetLastMotherPdg(parentBW.Encoding());
338	p2.SetLastMotherDecayCoor(parentBW.Pos());
339	p2.SetLastMotherDecayMom(parentBW.Mom());
340	p3.SetLastMotherPdg(parentBW.Encoding());
341	p3.SetLastMotherDecayCoor(parentBW.Pos());
342	p3.SetLastMotherDecayMom(parentBW.Mom());
343
344	//set to daughters the same type as has mother
345	p1.SetType(NB);
346	p2.SetType(NB);
347	p3.SetType(NB);
b1c2e580	348
b1c2e580	349	// energy conservation check in the lab system
	350	Double_t deltaS = TMath::Sqrt((parentBW.Mom().X()-p1.Mom().X()-p2.Mom().X()-p3.Mom().X())*(parentBW.Mom().X()-p1.Mom().X()-p2.Mom().X()-p3.Mom().X()) +
	351	(parentBW.Mom().Y()-p1.Mom().Y()-p2.Mom().Y()-p3.Mom().Y())*(parentBW.Mom().Y()-p1.Mom().Y()-p2.Mom().Y()-p3.Mom().Y()) +
	352	(parentBW.Mom().Z()-p1.Mom().Z()-p2.Mom().Z()-p3.Mom().Z())*(parentBW.Mom().Z()-p1.Mom().Z()-p2.Mom().Z()-p3.Mom().Z()) +
	353	(parentBW.Mom().E()-p1.Mom().E()-p2.Mom().E()-p3.Mom().E())*(parentBW.Mom().E()-p1.Mom().E()-p2.Mom().E()-p3.Mom().E()));
	354	// if deltaS is too big then repeat the kinematic procedure
	355	if(deltaS>0.001) {
7b7936e9	356	// cout << "3-body decay kinematic check in lab system: " << pDef->GetPDG() << " --> " << p1.Encoding() << " + " << p2.Encoding() << " + " << p3.Encoding() << endl;
	357	// cout << "Mother (e,px,py,pz): " << parentBW.Mom().E() << "\t" << parentBW.Mom().X() << "\t" << parentBW.Mom().Y() << "\t" << parentBW.Mom().Z() << endl;
	358	// cout << "Daughter1 (e,px,py,pz): " << p1.Mom().E() << "\t" << p1.Mom().X() << "\t" << p1.Mom().Y() << "\t" << p1.Mom().Z() << endl;
	359	// cout << "Daughter2 (e,px,py,pz): " << p2.Mom().E() << "\t" << p2.Mom().X() << "\t" << p2.Mom().Y() << "\t" << p2.Mom().Z() << endl;
	360	// cout << "Daughter3 (e,px,py,pz): " << p3.Mom().E() << "\t" << p3.Mom().X() << "\t" << p3.Mom().Y() << "\t" << p3.Mom().Z() << endl;
	361	// cout << "3-body decay delta(sqrtS) = " << deltaS << endl;
	362	// cout << "Repeating the decay algorithm..." << endl;
b1c2e580	363
	364	iterations++;
	365	continue;
	366	}
	367
3fa37a65	368	Int_t parentIndex = parent.GetIndex();
b1c2e580	369	p1.SetIndex();
	370	p2.SetIndex();
	371	p3.SetIndex();
	372	p1.SetMother(parentIndex);
	373	p2.SetMother(parentIndex);
	374	p3.SetMother(parentIndex);
3fa37a65	375	parent.SetFirstDaughterIndex(p1.GetIndex());
3fa37a65	376	parent.SetLastDaughterIndex(p3.GetIndex());
b1c2e580	377	allocator.AddParticle(p1, output);
	378	allocator.AddParticle(p2, output);
	379	allocator.AddParticle(p3, output);
	380	success = kTRUE;
	381	}
	382	}
	383	return;
	384	}