--- /dev/null
+//--------------------------------------------------------------------------
+//
+// Environment:
+// This software is part of the EvtGen package. If you use all or part
+// of it, please give an appropriate acknowledgement.
+//
+// Copyright Information: See EvtGen/COPYRIGHT
+//
+// Module: EvtGenModels/EvtBcToNPi.hh
+//
+// Description: General decay model for Bc -> V + npi and Bc -> P + npi
+//
+// Modification history:
+//
+// A.Berezhnoy, A.Likhoded, A.Luchinsky April 2011 Module created
+//
+//------------------------------------------------------------------------
+
+#include "EvtGenBase/EvtPatches.hh"
+
+#include "EvtGenBase/EvtPDL.hh"
+#include "EvtGenBase/EvtReport.hh"
+#include "EvtGenBase/EvtVector4C.hh"
+#include "EvtGenBase/EvtTensor4C.hh"
+#include "EvtGenBase/EvtIdSet.hh"
+#include "EvtGenBase/EvtSpinType.hh"
+#include "EvtGenBase/EvtScalarParticle.hh"
+
+#include "EvtGenModels/EvtBcToNPi.hh"
+
+#include <iostream>
+using std::endl;
+
+EvtBcToNPi::EvtBcToNPi(bool printAuthorInfo) {
+ nCall=0; maxAmp2=0;
+ if (printAuthorInfo == true) {this->printAuthorInfo();}
+}
+
+EvtBcToNPi::~EvtBcToNPi() {
+}
+
+std::string EvtBcToNPi::getName(){
+
+ return "EvtBcToNPi";
+
+}
+
+EvtDecayBase* EvtBcToNPi::clone(){
+
+ return new EvtBcToNPi;
+
+}
+
+
+void EvtBcToNPi::init(){
+
+ // check spins
+ checkSpinParent(EvtSpinType::SCALAR);
+
+
+ // the others are scalar
+ for (int i=1; i<=(getNDaug()-1);i++) {
+ checkSpinDaughter(i,EvtSpinType::SCALAR);
+ };
+
+ _beta=-0.108; _mRho=0.775; _gammaRho=0.149;
+ _mRhopr=1.364; _gammaRhopr=0.400; _mA1=1.23; _gammaA1=0.4;
+
+ // read arguments
+ if( EvtPDL::getSpinType(getDaug(0)) == EvtSpinType::VECTOR) {
+ checkNArg(10);
+ int n=0;
+ _maxProb=getArg(n++);
+ FA0_N=getArg(n++);
+ FA0_c1=getArg(n++);
+ FA0_c2=getArg(n++);
+ FAp_N=getArg(n++);
+ FAp_c1=getArg(n++);
+ FAp_c2=getArg(n++);
+ FV_N=getArg(n++);
+ FV_c1=getArg(n++);
+ FV_c2=getArg(n++);
+ FAm_N=0;
+ FAm_c1=0;
+ FAm_c2=0;
+ }
+ else if( EvtPDL::getSpinType(getDaug(0)) == EvtSpinType::SCALAR) {
+ checkNArg(4);
+ int n=0;
+ _maxProb=getArg(n++);
+ Fp_N=getArg(n++);
+ Fp_c1=getArg(n++);
+ Fp_c2=getArg(n++);
+ Fm_N=0;
+ Fm_c1=0;
+ Fm_c2=0;
+ }
+ else {
+ report(ERROR,"EvtGen") << "Have not yet implemented this final state in BCPSINPI model" << endl;
+ report(ERROR,"EvtGen") << "Ndaug="<<getNDaug() << endl;
+ for ( int id=0; id<(getNDaug()-1); id++ )
+ report(ERROR,"EvtGen") << "Daug " << id << " "<<EvtPDL::name(getDaug(id)).c_str() << endl;
+ return;
+
+ };
+
+ if(getNDaug()<2 || getNDaug()>4) {
+ report(ERROR,"EvtGen") << "Have not yet implemented this final state in BCPSINPI model" << endl;
+ report(ERROR,"EvtGen") << "Ndaug="<<getNDaug() << endl;
+ for ( int id=0; id<(getNDaug()-1); id++ )
+ report(ERROR,"EvtGen") << "Daug " << id << " "<<EvtPDL::name(getDaug(id)).c_str() << endl;
+ return;
+ }
+
+}
+
+double EvtBcToNPi::_ee(double M, double m1, double m2) {
+ return (M*M+m1*m1-m2*m2)/(2*M);
+};
+
+double EvtBcToNPi::_pp(double M, double m1, double m2) {
+ double __ee=_ee(M,m1,m2);
+ return sqrt(__ee*__ee-m1*m1);
+};
+
+
+void EvtBcToNPi::initProbMax(){
+ if(_maxProb>0.) setProbMax(_maxProb);
+ else {
+ EvtId id=getParentId();
+ EvtScalarParticle *p=new EvtScalarParticle();
+ p->init(id, EvtPDL::getMass(id),0., 0., 0.);
+ p->setDiagonalSpinDensity();
+ // add daughters
+ p->makeDaughters(getNDaug(), getDaugs() );
+
+ // fill the momenta
+ if(getNDaug()==2) {
+ double M=EvtPDL::getMass(id), m1=EvtPDL::getMass(getDaug(0)), m2=EvtPDL::getMass(getDaug(1));
+ double __pp=_pp(M,m1,m2);
+ p->getDaug(0)->setP4( EvtVector4R( _ee(M,m1,m2), 0., 0., __pp) );
+ p->getDaug(1)->setP4( EvtVector4R( _ee(M,m2,m1), 0., 0., -__pp) );
+ }
+ else if( getNDaug()==3) {
+ double M=EvtPDL::getMass(id),
+ m1=EvtPDL::getMass(getDaug(0)),
+ m2=EvtPDL::getMass(getDaug(1)),
+ m3=EvtPDL::getMass(getDaug(2));
+ double __ppRho=_pp(M,m1,_mRho), __ppPi=_pp(_mRho,m2,m3);
+ p->getDaug(0)->setP4( EvtVector4R( _ee(M,m1,_mRho), 0., 0., __ppRho) );
+ EvtVector4R _pRho( _ee(M,_mRho,m1), 0., 0., -__ppRho);
+ EvtVector4R _p2( _ee(_mRho, m2, m3), 0., 0., __ppPi); _p2.applyBoostTo(_pRho);
+ EvtVector4R _p3( _ee(_mRho, m2, m3), 0., 0., -__ppPi); _p3.applyBoostTo(_pRho);
+ p->getDaug(1)->setP4(_p2);
+ p->getDaug(2)->setP4(_p3);
+
+ }
+ else if( getNDaug()==4) {
+ double M=EvtPDL::getMass(id),
+ m1=EvtPDL::getMass(getDaug(0)),
+ m2=EvtPDL::getMass(getDaug(1)),
+ m3=EvtPDL::getMass(getDaug(2)),
+ m4=EvtPDL::getMass(getDaug(3));
+ if(M<m1+_mA1) return;
+ double __ppA1=_pp(M,m1,_mA1),
+ __ppRho=_pp(_mA1,_mRho,m4),
+ __ppPi=_pp(_mRho, m2, m3);
+ p->getDaug(0)->setP4( EvtVector4R( _ee(M,m1,_mRho), 0., 0., __ppA1) );
+ EvtVector4R _pA1( _ee(M,_mA1,m1), 0., 0., -__ppA1);
+ EvtVector4R _pRho(_ee(_mA1, _mRho, m4), 0, 0, __ppRho);
+ _pRho.applyBoostTo(_pA1);
+ EvtVector4R _p4( _ee(_mA1, m4, _mRho), 0, 0, -__ppRho); _p4.applyBoostTo(_pA1);
+ p->getDaug(3)->setP4(_p4);
+ EvtVector4R _p2( _ee(_mRho, m2, m3), 0, 0, __ppPi); _p2.applyBoostTo(_pRho);
+ p->getDaug(1)->setP4(_p2);
+ EvtVector4R _p3( _ee(_mRho, m2, m3), 0, 0, -__ppPi); _p2.applyBoostTo(_pRho);
+ p->getDaug(2)->setP4(_p3);
+ };
+
+
+ _amp2.init(p->getId(),getNDaug(),getDaugs());
+
+ decay(p);
+
+ EvtSpinDensity rho=_amp2.getSpinDensity();
+
+ double prob=p->getSpinDensityForward().normalizedProb(rho);
+
+ if(prob>0) setProbMax(0.9*prob);
+
+
+ };
+}
+
+void EvtBcToNPi::decay( EvtParticle *root_particle ){
+ ++nCall;
+
+ EvtIdSet thePis("pi+","pi-","pi0");
+ EvtComplex I=EvtComplex(0.0, 1.0);
+
+
+ root_particle->initializePhaseSpace(getNDaug(),getDaugs());
+
+ EvtVector4R
+ p(root_particle->mass(), 0., 0., 0.), // Bc momentum
+ k=root_particle->getDaug(0)->getP4(), // J/psi momenta
+ Q=p-k;
+
+ double Q2=Q.mass2();
+
+
+// check pi-mesons and calculate hadronic current
+ EvtVector4C hardCur;
+ bool foundHadCurr=false;
+
+ if ( getNDaug() == 2 ) // Bc -> psi pi+
+ {
+ hardCur=Q;
+ foundHadCurr=true;
+ }
+ else if ( getNDaug() == 3 ) // Bc -> psi pi+ pi0
+ {
+ EvtVector4R p1,p2;
+ p1=root_particle->getDaug(1)->getP4(), // pi+ momenta
+ p2=root_particle->getDaug(2)->getP4(), // pi0 momentum
+ hardCur=Fpi(p1,p2)*(p1-p2);
+ foundHadCurr=true;
+ }
+ else if( getNDaug()==4 ) // Bc -> psi pi+ pi pi
+ {
+ int diffPi(0),samePi1(0),samePi2(0);
+ if ( getDaug( 1) == getDaug( 2) ) {diffPi= 3; samePi1= 1; samePi2= 2;}
+ if ( getDaug( 1) == getDaug( 3) ) {diffPi= 2; samePi1= 1; samePi2= 3;}
+ if ( getDaug( 2) == getDaug( 3) ) {diffPi= 1; samePi1= 2; samePi2= 3;}
+
+ EvtVector4R p1=root_particle->getDaug(samePi1)->getP4();
+ EvtVector4R p2=root_particle->getDaug(samePi2)->getP4();
+ EvtVector4R p3=root_particle->getDaug(diffPi)->getP4();
+
+ EvtComplex BA1;
+ double GA1=_gammaA1*pi3G(Q2,samePi1)/pi3G(_mA1*_mA1,samePi1);
+ EvtComplex denBA1(_mA1*_mA1 - Q.mass2(),-1.*_mA1*GA1);
+ BA1 = _mA1*_mA1 / denBA1;
+
+ hardCur = BA1*( (p1-p3) - (Q*(Q*(p1-p3))/Q2)*Fpi(p2,p3) +
+ (p2-p3) - (Q*(Q*(p2-p3))/Q2)*Fpi(p1,p3) );
+ foundHadCurr=true;
+ }
+
+ if ( !foundHadCurr ) {
+ report(ERROR,"EvtGen") << "Have not yet implemented this final state in BCNPI model" << endl;
+ report(ERROR,"EvtGen") << "Ndaug="<<getNDaug() << endl;
+ int id;
+ for ( id=0; id<(getNDaug()-1); id++ )
+ report(ERROR,"EvtGen") << "Daug " << id << " "<<EvtPDL::name(getDaug(id)).c_str() << endl;
+ ::abort();
+ };
+
+ EvtTensor4C H;
+ double amp2=0.;
+ if( root_particle->getDaug(0)->getSpinType() == EvtSpinType::VECTOR) {
+ double FA0=FA0_N*exp(FA0_c1*Q2 + FA0_c2*Q2*Q2);
+ double FAp=FAp_N*exp(FAp_c1*Q2 + FAp_c2*Q2*Q2);
+ double FAm=FAm_N*exp(FAm_c1*Q2 + FAm_c2*Q2*Q2);
+ double FV= FV_N* exp( FV_c1*Q2 + FV_c2*Q2*Q2 );
+ H=-FA0*EvtTensor4C::g()
+ -FAp*EvtGenFunctions::directProd(p,p+k)
+ +FAm*EvtGenFunctions::directProd(p,p-k)
+ +2*I*FV*dual(EvtGenFunctions::directProd(p,k));
+ EvtVector4C Heps=H.cont2(hardCur);
+
+ for(int i=0; i<4; i++) {
+ EvtVector4C eps=root_particle->getDaug(0)->epsParent(i).conj(); // psi-meson polarization vector
+ EvtComplex amp=eps*Heps;
+ vertex(i,amp);
+ amp2+=pow( abs(amp),2);
+ }
+ }
+ else if( root_particle->getDaug(0)->getSpinType() == EvtSpinType::SCALAR) {
+ double Fp=Fp_N*exp(Fp_c1*Q2 + Fp_c2*Q2*Q2);
+ double Fm=Fm_N*exp(Fm_c1*Q2 + Fm_c2*Q2*Q2);
+ EvtVector4C H=Fp*(p+k)+Fm*(p-k);
+ EvtComplex amp=H*hardCur;
+ vertex(amp);
+ amp2+=pow( abs(amp),2);
+ };
+ if(amp2>maxAmp2) maxAmp2=amp2;
+
+ return ;
+}
+
+EvtComplex EvtBcToNPi::Fpi( EvtVector4R q1, EvtVector4R q2) {
+ double m1=q1.mass();
+ double m2=q2.mass();
+
+ EvtVector4R Q = q1 + q2;
+ double mQ2= Q*Q;
+
+ // momenta in the rho->pipi decay
+ double dRho= _mRho*_mRho - m1*m1 - m2*m2;
+ double pPiRho = (1.0/_mRho)*sqrt((dRho*dRho)/4.0 - m1*m1*m2*m2);
+
+ double dRhopr= _mRhopr*_mRhopr - m1*m1 - m2*m2;
+ double pPiRhopr = (1.0/_mRhopr)*sqrt((dRhopr*dRhopr)/4.0 - m1*m1*m2*m2);
+
+ double dQ= mQ2 - m1*m1 - m2*m2;
+ double pPiQ = (1.0/sqrt(mQ2))*sqrt((dQ*dQ)/4.0 - m1*m1*m2*m2);
+
+
+ double gammaRho = _gammaRho*_mRho/sqrt(mQ2)*pow((pPiQ/pPiRho),3);
+ EvtComplex BRhoDem(_mRho*_mRho - mQ2,-1.0*_mRho*gammaRho);
+ EvtComplex BRho= _mRho*_mRho / BRhoDem;
+
+ double gammaRhopr = _gammaRhopr*_mRhopr/sqrt(mQ2)*pow((pPiQ/pPiRhopr),3);
+ EvtComplex BRhoprDem(_mRhopr*_mRhopr - mQ2,-1.0*_mRho*gammaRhopr);
+ EvtComplex BRhopr= _mRhopr*_mRhopr / BRhoprDem;
+
+ return (BRho + _beta*BRhopr)/(1+_beta);
+}
+
+double EvtBcToNPi::pi3G(double m2,int dupD) {
+ double mPi= EvtPDL::getMeanMass(getDaug(dupD));
+ if ( m2 > (_mRho+mPi) ) {
+ return m2*(1.623 + 10.38/m2 - 9.32/(m2*m2) + 0.65/(m2*m2*m2));
+ }
+ else {
+ double t1=m2-9.0*mPi*mPi;
+ return 4.1*pow(t1,3.0)*(1.0 - 3.3*t1+5.8*t1*t1);
+ }
+}
+
+void EvtBcToNPi::printAuthorInfo() {
+
+ report(INFO,"EvtGen")<<"Defining EvtBcToNPi model: Bc -> V + npi and Bc -> P + npi decays\n"
+ <<"from A.V. Berezhnoy, A.K. Likhoded, A.V. Luchinsky: "
+ <<"Phys.Rev.D 82, 014012 (2010) and arXiV:1104.0808."<<endl;
+
+}
+
git://git.uio.no / u / mrichter / AliRoot.git / blobdiff