//=============================================================================
// decay particle
//=============================================================================
void EvtBToDDalitzCPK::decay( EvtParticle * p )
{
if ( _flag == 1 ) {
// PHSP
p -> initializePhaseSpace( getNDaug() , getDaugs() ) ;
vertex ( 0. ) ;
}
else if ( _flag == 2 ) {
// SVS
p->initializePhaseSpace(getNDaug(),getDaugs());
EvtParticle *v;
v = p->getDaug(0);
double massv = v->mass();
EvtVector4R momv = v->getP4();
EvtVector4R moms = p->getDaug(1)->getP4();
double m_parent = p->mass();
EvtVector4R p4_parent = momv+moms;
double norm=massv/(momv.d3mag()*m_parent);
p4_parent = norm*p4_parent;
vertex(0,p4_parent*(v->epsParent(0)));
vertex(1,p4_parent*(v->epsParent(1)));
vertex(2,p4_parent*(v->epsParent(2)));
}
}
//======================================================
void EvtBcVNpi::init(){
//cout<<"BcVNpi::init()"<<endl;
checkNArg(1);
checkSpinParent(EvtSpinType::SCALAR);
checkSpinDaughter(0,EvtSpinType::VECTOR);
for (int i=1; i<=(getNDaug()-1);i++) {
checkSpinDaughter(i,EvtSpinType::SCALAR);
};
if(getNDaug()<2 || getNDaug()>6) {
report(Severity::Error,"EvtGen") << "Have not yet implemented this final state in BcVNpi model" << endl;
report(Severity::Error,"EvtGen") << "Ndaug="<<getNDaug() << endl;
for ( int id=0; id<(getNDaug()-1); id++ )
report(Severity::Error,"EvtGen") << "Daug " << id << " "<<EvtPDL::name(getDaug(id)).c_str() << endl;
return;
}
// for(int i=0; i<getNDaug(); i++)
// cout<<"BcVNpi::init \t\t daughter "<<i<<" : "<<getDaug(i).getId()<<" "<<EvtPDL::name(getDaug(i)).c_str()<<endl;
idVector = getDaug(0).getId();
whichfit = int(getArg(0)+0.1);
// cout<<"BcVNpi: whichfit ="<<whichfit<<" idVector="<<idVector<<endl;
ffmodel = new EvtBCVFF(idVector,whichfit);
wcurr = new EvtWnPi();
nCall = 0;
}
void EvtBcBsNPi::initProbMax() {
if ( getNDaug() == 2 ) {
setProbMax(250.);
} else if ( getNDaug() == 3 ) {
setProbMax(25000.);// checked at 30k events
} else if( getNDaug() == 4 ) {
setProbMax(45000.); // checked at 30k events
}
}
void EvtPropSLPole::decay( EvtParticle *p ){
if(! _isProbMaxSet){
EvtId parnum,mesnum,lnum,nunum;
parnum = getParentId();
mesnum = getDaug(0);
lnum = getDaug(1);
nunum = getDaug(2);
double mymaxprob = calcMaxProb(parnum,mesnum,
lnum,nunum,SLPoleffmodel);
setProbMax(mymaxprob);
_isProbMaxSet = true;
}
double minKstMass = EvtPDL::getMinMass(p->getDaug(0)->getId());
double maxKstMass = EvtPDL::getMaxMass(p->getDaug(0)->getId());
EvtIntervalFlatPdf flat(minKstMass, maxKstMass);
EvtPdfGen<EvtPoint1D> gen(flat);
EvtPoint1D point = gen();
double massKst = point.value();
p->getDaug(0)->setMass(massKst);
p->initializePhaseSpace(getNDaug(),getDaugs());
// EvtVector4R p4meson = p->getDaug(0)->getP4();
calcamp->CalcAmp(p,_amp2,SLPoleffmodel);
EvtParticle *mesonPart = p->getDaug(0);
double meson_BWAmp = calBreitWigner(mesonPart, point);
int list[2];
list[0]=0; list[1]=0;
_amp2.vertex(0,0,_amp2.getAmp(list)*meson_BWAmp);
list[0]=0; list[1]=1;
_amp2.vertex(0,1,_amp2.getAmp(list)*meson_BWAmp);
list[0]=1; list[1]=0;
_amp2.vertex(1,0,_amp2.getAmp(list)*meson_BWAmp);
list[0]=1; list[1]=1;
_amp2.vertex(1,1,_amp2.getAmp(list)*meson_BWAmp);
list[0]=2; list[1]=0;
_amp2.vertex(2,0,_amp2.getAmp(list)*meson_BWAmp);
list[0]=2; list[1]=1;
_amp2.vertex(2,1,_amp2.getAmp(list)*meson_BWAmp);
return;
}
void EvtTauVectornu::decay(EvtParticle *p){
static EvtId TAUM=EvtPDL::getId("tau-");
p->initializePhaseSpace(getNDaug(),getDaugs());
EvtParticle *v, *nut;
v=p->getDaug(0);
nut=p->getDaug(1);
double mvec = v->mass();
EvtVector4C tau1, tau2;
if (p->getId()==TAUM) {
tau1=EvtLeptonVACurrent(nut->spParentNeutrino(),p->sp(0));
tau2=EvtLeptonVACurrent(nut->spParentNeutrino(),p->sp(1));
}
else{
tau1=EvtLeptonVACurrent(p->sp(0),nut->spParentNeutrino());
tau2=EvtLeptonVACurrent(p->sp(1),nut->spParentNeutrino());
}
double norm=mvec*sqrt(mvec);
vertex(0,0,norm*tau1*(v->epsParent(0).conj()));
vertex(0,1,norm*tau1*(v->epsParent(1).conj()));
vertex(0,2,norm*tau1*(v->epsParent(2).conj()));
vertex(1,0,norm*tau2*(v->epsParent(0).conj()));
vertex(1,1,norm*tau2*(v->epsParent(1).conj()));
vertex(1,2,norm*tau2*(v->epsParent(2).conj()));
return;
}
void EvtISGW2::decay( EvtParticle *p ) {
p->initializePhaseSpace(getNDaug(),getDaugs());
calcamp->CalcAmp(p,_amp2,isgw2ffmodel);
}
void EvtbsToLLLL::decay( EvtParticle *p ){
double mu = getArg(0); // the scale parameter
int Nf = (int) getArg(1); // number of "effective" flavors
int res_swch = (int) getArg(2); // resonant switching parametr
int ias = (int) getArg(3); // switching parametr for \alpha_s(M_Z)
double CKM_A = getArg(4);
double CKM_lambda = getArg(5);
double CKM_barrho = getArg(6);
double CKM_bareta = getArg(7);
p->initializePhaseSpace(getNDaug(),getDaugs());
_calcamp->CalcAmp(p,_amp2, _mntffmodel, _wilscoeff, mu, Nf, res_swch, ias,
CKM_A,CKM_lambda,CKM_barrho,CKM_bareta);
// EvtGenReport(NOTICE,"EvtGen") << "\n The function EvtbTosllMSExt::decay(...) passed with arguments:"
// << "\n mu = " << mu << " Nf =" << Nf
// << " res_swch = " << res_swch
// << " ias = " << ias
// << " CKM_A = " << CKM_A
// << " CKM_lambda = " << CKM_lambda
// << " CKM_barrho = " << CKM_barrho
// << " CKM_bareta = " << CKM_bareta
// << " ReA7 = " << ReA7
// << " ImA7 = " << ImA7
// << " ReA10 = " << ReA10
// << " ImA10 = " << ImA10 << std::endl;
}
void EvtB2MuMuMuNu::decay( EvtParticle *p ){
p->initializePhaseSpace(getNDaug(),getDaugs());
_calcamp->CalcAmp(p,_amp2, _msffmodel);
}
void EvtHypNonLepton::init() {
if(getNArg()<2 || getNArg()>3) { // alpha phi gamma delta
EvtGenReport(EVTGEN_ERROR,"EvtGen") << " ERROR: EvtHypNonLepton generator expected 2 or 3 arguments but found: " << getNArg() << std::endl;
EvtGenReport(EVTGEN_INFO ,"EvtGen") << " 1. Decay asymmetry parameter - alpha" << std::endl;
EvtGenReport(EVTGEN_INFO ,"EvtGen") << " 2. Parameter phi - in degrees (not radians)" << std::endl;
EvtGenReport(EVTGEN_INFO ,"EvtGen") << " 3. Note on every x-th decay" << std::endl;
::abort();
}
if(getNDaug()!=2) { // Check that there are 2 daughters only
EvtGenReport(EVTGEN_ERROR,"EvtGen") << " ERROR: EvtHypNonLepton generator expected 2 daughters but found: " << getNDaug() << std::endl;
::abort();
}
// Check particles spins
if(EvtSpinType::getSpin2(EvtPDL::getSpinType(getParentId()))!=1) {
EvtGenReport(EVTGEN_ERROR,"EvtGen") << " ERROR: EvtHypNonLepton generator expected dirac parent particle, but found " << EvtSpinType::getSpin2(EvtPDL::getSpinType(getParentId())) << " spin degrees of freedom" << std::endl;
::abort();
}
if(EvtSpinType::getSpin2(EvtPDL::getSpinType(getDaug(0)))!=1) {
EvtGenReport(EVTGEN_ERROR,"EvtGen") << " ERROR: EvtHypNonLepton generator expected the first child to be dirac particle, but found " << EvtSpinType::getSpin2(EvtPDL::getSpinType(getDaug(0))) << " spin degrees of freedom" << std::endl;
::abort();
}
if(EvtSpinType::getSpin2(EvtPDL::getSpinType(getDaug(1)))!=0) {
EvtGenReport(EVTGEN_ERROR,"EvtGen") << " ERROR: EvtHypNonLepton generator expected the second child to be scalar particle, but found " << EvtSpinType::getSpin2(EvtPDL::getSpinType(getDaug(1))) << " spin degrees of freedom" << std::endl;
::abort();
}
// Read all parameters
m_alpha = getArg(0);
m_phi = getArg(1)*EvtConst::pi/180;
if(getNArg()==3) m_noTries = static_cast<long>(getArg(2));
else m_noTries = 0;
// calculate additional parameters
double p,M,m1,m2;
double p_to_s,beta,delta,gamma;
M = EvtPDL::getMass(getParentId());
m1 = EvtPDL::getMass(getDaug(0));
m2 = EvtPDL::getMass(getDaug(1));
if(m1+m2>=M) {
EvtGenReport(EVTGEN_ERROR,"EvtGen") << " ERROR: EvtHypNonLepton found impossible decay: " << M << " --> " << m1 << " + " << m2 << " GeV\n" << std::endl;
::abort();
}
p = sqrt(M*M-(m1+m2)*(m1+m2))*sqrt(M*M-(m1-m2)*(m1-m2))/2./M;
beta = sqrt(1.-m_alpha*m_alpha)*sin(m_phi);
delta = -atan2(beta,m_alpha);
gamma = sqrt(1.-m_alpha*m_alpha-beta*beta);
p_to_s = sqrt((1.-gamma)/(1.+gamma));
m_B_to_A = p_to_s*(m1+sqrt(p*p+m1*m1))/p*EvtComplex(cos(delta),sin(delta));
}
//======================================================
void EvtBcVNpi::initProbMax() {
// cout<<"BcVNpi::initProbMax()"<<endl;
if(idVector == EvtPDL::getId("J/psi").getId() && whichfit == 1 && getNDaug()==6) setProbMax(720000.);
else if(idVector == EvtPDL::getId("J/psi").getId() && whichfit == 2 && getNDaug()==6) setProbMax(471817.);
else if(idVector == EvtPDL::getId("J/psi").getId() && whichfit == 1 && getNDaug()==4) setProbMax(42000.);
else if(idVector == EvtPDL::getId("J/psi").getId() && whichfit == 2 && getNDaug()==4) setProbMax(16000.);
else if(idVector == EvtPDL::getId("psi(2S)").getId() && whichfit == 1 && getNDaug()==4) setProbMax(1200.);
else if(idVector == EvtPDL::getId("psi(2S)").getId() && whichfit == 2 && getNDaug()==4) setProbMax(2600.);
else if(idVector == EvtPDL::getId("psi(2S)").getId() && whichfit == 1 && getNDaug()==6) setProbMax(40000.);
else if(idVector == EvtPDL::getId("psi(2S)").getId() && whichfit == 2 && getNDaug()==6) setProbMax(30000.);
}
void EvtBcBsNPi::init() {
checkNArg(0);
// check spins
checkSpinParent(EvtSpinType::SCALAR);
checkSpinDaughter(0,EvtSpinType::SCALAR);
// the others are scalar
for (int i=1; i<=(getNDaug()-1);i++) {
checkSpinDaughter(i,EvtSpinType::SCALAR);
}
}
void EvtVSSMix::decay( EvtParticle *p ){
//added by Lange Jan4,2000
static EvtId B0=EvtPDL::getId("B0");
static EvtId B0B=EvtPDL::getId("anti-B0");
p->initializePhaseSpace(getNDaug(),getDaugs());
EvtParticle *s1,*s2;
s1 = p->getDaug(0);
s2 = p->getDaug(1);
EvtVector4R s1mom = s1->getP4();
double t1,t2,dm;
s1->setLifetime();
s2->setLifetime();
t1=s1->getLifetime();
t2=s2->getLifetime();
//dm should probably be a parameter to this model.
dm=getArg(0)/EvtConst::c;
EvtId d1,d2;
d1=s1->getId();
d2=s2->getId();
double mix_amp=0.;
if (d1==B0&&d2==B0B) mix_amp=cos(0.5*dm*(t1-t2));
if (d1==B0B&&d2==B0) mix_amp=cos(0.5*dm*(t1-t2));
if (d1==B0&&d2==B0) mix_amp=sin(0.5*dm*(t1-t2));
if (d1==B0B&&d2==B0B) mix_amp=sin(0.5*dm*(t1-t2));
double norm=1.0/s1mom.d3mag();
vertex(0,norm*mix_amp*s1mom*(p->eps(0)));
vertex(1,norm*mix_amp*s1mom*(p->eps(1)));
vertex(2,norm*mix_amp*s1mom*(p->eps(2)));
return ;
}
void EvtEtaDalitz::decay( EvtParticle *p){
p->initializePhaseSpace(getNDaug(),getDaugs());
EvtVector4R mompi0 = p->getDaug(2)->getP4();
double masspip = p->getDaug(0)->mass();
double masspim = p->getDaug(1)->mass();
double masspi0 = p->getDaug(2)->mass();
double m_eta = p->mass();
double y;
//The decay amplitude coems from Layter et al PRD 7 2565 (1973).
y=(mompi0.get(0)-masspi0)*(3.0/(m_eta-masspip-masspim-masspi0))-1.0;
EvtComplex amp(sqrt(1.0-1.07*y),0.0);
vertex(amp);
return ;
}
void EvtVVP::decay(EvtParticle *p){
p->initializePhaseSpace(getNDaug(),getDaugs());
EvtParticle *v,*ph;
v = p->getDaug(0);
ph = p->getDaug(1);
EvtVector3C epsp[3];
EvtVector3C epsv[3];
EvtVector3C epsph[2];
epsp[0]=p->eps(0).vec();
epsp[1]=p->eps(1).vec();
epsp[2]=p->eps(2).vec();
epsv[0]=v->eps(0).vec().conj();
epsv[1]=v->eps(1).vec().conj();
epsv[2]=v->eps(2).vec().conj();
epsph[0]=ph->epsParentPhoton(0).vec().conj();
epsph[1]=ph->epsParentPhoton(1).vec().conj();
int i,j,k;
for(i=0;i<3;i++){
for(j=0;j<3;j++){
for(k=0;k<2;k++){
vertex(i,j,k,epsp[i].cross(epsv[j])*epsph[k]);
}
}
}
return;
}
void EvtSSSCP::decay( EvtParticle *p ){
//added by Lange Jan4,2000
static EvtId B0=EvtPDL::getId("B0");
static EvtId B0B=EvtPDL::getId("anti-B0");
double t;
EvtId other_b;
EvtCPUtil::getInstance()->OtherB(p,t,other_b,0.5);
p->initializePhaseSpace(getNDaug(),getDaugs());
EvtComplex amp;
EvtComplex A,Abar;
A=EvtComplex(getArg(3)*cos(getArg(4)),getArg(3)*sin(getArg(4)));
Abar=EvtComplex(getArg(5)*cos(getArg(6)),getArg(5)*sin(getArg(6)));
if (other_b==B0B){
amp=A*cos(getArg(1)*t/(2*EvtConst::c))+
EvtComplex(cos(-2.0*getArg(0)),sin(-2.0*getArg(0)))*
getArg(2)*EvtComplex(0.0,1.0)*Abar*sin(getArg(1)*t/(2*EvtConst::c));
}
if (other_b==B0){
amp=A*EvtComplex(cos(2.0*getArg(0)),sin(2.0*getArg(0)))*
EvtComplex(0.0,1.0)*sin(getArg(1)*t/(2*EvtConst::c))+
getArg(2)*Abar*cos(getArg(1)*t/(2*EvtConst::c));
}
vertex(amp);
return ;
}
void EvtD0gammaDalitz::decay( EvtParticle* part )
{
// Check if the D is from a B+- -> D0 K+- decay with the appropriate model.
EvtParticle* parent = part->getParent(); // If there are no mistakes, should be B+ or B-.
if (parent != 0 && EvtDecayTable::getInstance()->getDecayFunc( parent )->getName() == "BTODDALITZCPK" )
{
EvtId parId = parent->getId();
if ( ( parId == _BP ) || ( parId == _BM ) ||
( parId == _B0 ) || ( parId == _B0B) )
{
_bFlavor = parId;
}
else
{
reportInvalidAndExit();
}
}
else
{
reportInvalidAndExit();
}
// Read the D decay parameters from the B decay model.
// Gamma angle in rad.
double gamma = EvtDecayTable::getInstance()->getDecayFunc( parent )->getArg( 0 );
// Strong phase in rad.
double delta = EvtDecayTable::getInstance()->getDecayFunc( parent )->getArg( 1 );
// Ratio between B->D0K and B->D0barK
double rB = EvtDecayTable::getInstance()->getDecayFunc( parent )->getArg( 2 );
// Same structure for all of these decays.
part->initializePhaseSpace( getNDaug(), getDaugs() );
EvtVector4R pA = part->getDaug( _d1 )->getP4();
EvtVector4R pB = part->getDaug( _d2 )->getP4();
EvtVector4R pC = part->getDaug( _d3 )->getP4();
// Squared invariant masses.
double mSqAB = ( pA + pB ).mass2();
double mSqAC = ( pA + pC ).mass2();
double mSqBC = ( pB + pC ).mass2();
EvtComplex amp( 1.0, 0.0 );
// Direct and conjugated amplitudes.
EvtComplex ampDir;
EvtComplex ampCnj;
if ( _isKsPiPi )
{
// Direct and conjugated Dalitz points.
EvtDalitzPoint pointDir( _mKs, _mPi, _mPi, mSqAB, mSqBC, mSqAC );
EvtDalitzPoint pointCnj( _mKs, _mPi, _mPi, mSqAC, mSqBC, mSqAB );
// Direct and conjugated amplitudes.
ampDir = dalitzKsPiPi( pointDir );
ampCnj = dalitzKsPiPi( pointCnj );
}
else
{
// Direct and conjugated Dalitz points.
EvtDalitzPoint pointDir( _mKs, _mK, _mK, mSqAB, mSqBC, mSqAC );
EvtDalitzPoint pointCnj( _mKs, _mK, _mK, mSqAC, mSqBC, mSqAB );
// Direct and conjugated amplitudes.
ampDir = dalitzKsKK( pointDir );
ampCnj = dalitzKsKK( pointCnj );
}
if ( _bFlavor == _BP || _bFlavor == _B0 )
{
amp = ampCnj + rB * exp( EvtComplex( 0., delta + gamma ) ) * ampDir;
}
else
{
amp = ampDir + rB * exp( EvtComplex( 0., delta - gamma ) ) * ampCnj;
}
vertex( amp );
return;
}
void EvtKstarnunu::decay(EvtParticle *p){
static EvtId NUE=EvtPDL::getId("nu_e");
static EvtId NUM=EvtPDL::getId("nu_mu");
static EvtId NUT=EvtPDL::getId("nu_tau");
static EvtId NUEB=EvtPDL::getId("anti-nu_e");
static EvtId NUMB=EvtPDL::getId("anti-nu_mu");
static EvtId NUTB=EvtPDL::getId("anti-nu_tau");
p->initializePhaseSpace(getNDaug(),getDaugs());
double m_b = p->mass();
EvtParticle *meson, *neutrino1, *neutrino2;
meson = p->getDaug(0);
neutrino1 = p->getDaug(1);
neutrino2 = p->getDaug(2);
EvtVector4R momnu1 = neutrino1->getP4();
EvtVector4R momnu2 = neutrino2->getP4();
EvtVector4R momkstar = meson->getP4();
double v0_0, a1_0, a2_0;
double m2v0, a1_b, a2_b;
v0_0 = 0.47;
a1_0 = 0.37;
a2_0 = 0.40;
m2v0 = 5.*5.;
a1_b = -0.023;
a2_b = 0.034;
EvtVector4R q = momnu1+momnu2;
double q2 = q.mass2();
double v0, a1, a2;
v0 = v0_0/(1-q2/m2v0);
a1 = a1_0*(1+a1_b*q2);
a2 = a2_0*(1+a2_b*q2);
EvtVector4R p4b; p4b.set(m_b,0.,0.,0.); // Do calcs in mother rest frame
double m_k = meson->mass();
EvtTensor4C tds=(-2*v0/(m_b+m_k))*dual(EvtGenFunctions::directProd(p4b,momkstar))
- EvtComplex(0.0,1.0)*
( (m_b+m_k)*a1*EvtTensor4C::g()
- (a2/(m_b+m_k))*EvtGenFunctions::directProd(p4b-momkstar,p4b+momkstar));
EvtVector4C l;
if (getDaug(1)==NUE||getDaug(1)==NUM||getDaug(1)==NUT) {
l=EvtLeptonVACurrent(neutrino1->spParentNeutrino(),
neutrino2->spParentNeutrino());
}
if (getDaug(1)==NUEB||getDaug(1)==NUMB||getDaug(1)==NUTB) {
l=EvtLeptonVACurrent(neutrino2->spParentNeutrino(),
neutrino1->spParentNeutrino());
}
EvtVector4C et0,et1,et2;
et0 = tds.cont1( meson->epsParent(0).conj() );
et1 = tds.cont1( meson->epsParent(1).conj() );
et2 = tds.cont1( meson->epsParent(2).conj() );
vertex(0,l*et0);
vertex(1,l*et1);
vertex(2,l*et2);
return;
}
void EvtHypNonLepton::decay(EvtParticle* parent) {
parent->initializePhaseSpace(getNDaug(),getDaugs());
calcAmp(&_amp2,parent);
}
void EvtVectorIsr::decay( EvtParticle *p ){
//the elctron mass
double electMass=EvtPDL::getMeanMass(EvtPDL::getId("e-"));
static EvtId gammaId=EvtPDL::getId("gamma");
EvtParticle *phi;
EvtParticle *gamma;
//4-mom of the two colinear photons to the decay of the vphoton
EvtVector4R p4softg1(0.,0.,0.,0.);
EvtVector4R p4softg2(0.,0.,0.,0.);
//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);
//Generate soft colinear photons and the electron and positron energies after emission.
//based on method of AfkQed and notes of Vladimir Druzhinin.
//
//function ckhrad(eb,q2m,r1,r2,e01,e02,f_col)
//eb: energy of incoming electrons in CM frame
//q2m: minimum invariant mass of the virtual photon after soft colinear photon emission
//returned arguments
//e01,e02: energies of e+ and e- after soft colinear photon emission
//fcol: weighting factor for Born cross section for use in an accept/reject test.
double wcm=p->mass();
double eb=0.5*wcm;
//TO guarantee the collinear photons are softer than the ISR photon, require q2m > m*wcm
double q2m=phi->mass()*wcm;
double f_col(0.);
double e01(0.);
double e02(0.);
double ebeam=eb;
double wcm_new = wcm;
double s_new = wcm*wcm;
double fran = 1.;
double f = 0;
int m = 0;
double largest_f=0;//only used when determining max weight for this vector particle mass
if (!firstorder){
while (fran > f){
m++;
int n=0;
while (f_col == 0.){
n++;
ckhrad(eb,q2m,e01,e02,f_col);
if (n > 10000){
report(Severity::Info,"EvtGen") << "EvtVectorIsr is having problems. Called ckhrad 10000 times.\n";
assert(0);
}
}
//Effective beam energy after soft photon emission (neglecting electron mass)
ebeam = sqrt(e01*e02);
wcm_new = 2*ebeam;
s_new = wcm_new*wcm_new;
//The Vector mass should never be greater than wcm_new
if (phi->mass() > wcm_new){
report(Severity::Info,"EvtGen") << "EvtVectorIsr finds Vector mass="<<phi->mass()<<" > Weff=" << wcm_new<<". Should not happen\n";
assert(0);
}
//Determine Born cross section @ wcm_new for e+e- -> gamma V. We aren't interested in the absolute normalization
//Just the functional dependence. Assuming a narrow resonance when determining cs_Born
double cs_Born = 1.;
if (EvtPDL::getMaxRange(phi->getId()) > 0.) {
double x0 = 1 - EvtPDL::getMeanMass(phi->getId())*EvtPDL::getMeanMass(phi->getId())/s_new;
//L = log(s/(electMass*electMass)
double L = 2.*log(wcm_new/electMass);
// W(x0) is actually 2*alpha/pi times the following
double W = (L-1.)*(1. - x0 +0.5*x0*x0);
//Born cross section is actually 12*pi*pi*Gammaee/EvtPDL::getMeanMass(phi->getId()) times the following
//(we'd need the full W(x0) as well)
cs_Born = W/s_new;
}
f = cs_Born*f_col;
//if fmax was set properly, f should NEVER be larger than fmax
if (f > fmax && fmax > 0.){
report(Severity::Info,"EvtGen") << "EvtVectorIsr finds a problem with fmax, the maximum weight setting\n"
<< "fmax is the third decay argument in the .dec file. VectorIsr attempts to set it reasonably if it wasn't provided\n"
<< "To determine a more appropriate value, build GeneratorQAApp, and set the third argument for this decay <0.\n"
<< "If you haven't been providing the first 2 arguments, set them to be 1. 1.). The program will report\n"
<< "the largest weight it finds. You should set fmax to be slightly larger.\n"
<< "Alternatively try the following values for various vector particles: "
<< "phi->1.15 J/psi-psi(4415)->0.105\n"
<< "The current value of f and fmax for " << EvtPDL::name(phi->getId()) << " are " << f << " " << fmax << "\n"
<< "Will now assert\n";
assert(0);
}
if (fmax > 0.) {
fran = fmax*EvtRandom::Flat(0.0,1.0);
}
else {
//determine max weight for this vector particle mass
if (f>largest_f) {
largest_f = f;
report(Severity::Info,"EvtGen") << m << " " << EvtPDL::name(phi->getId()) << " "
<< "vector_mass "
<< " " << EvtPDL::getMeanMass(phi->getId()) << " fmax should be at least " << largest_f
<< ". f_col cs_B = " << f_col << " " << cs_Born
<< std::endl;
}
if (m%10000 == 0) {
report(Severity::Info,"EvtGen") << m << " " << EvtPDL::name(phi->getId()) << " "
<< "vector_mass "
<< " " << EvtPDL::getMeanMass(phi->getId()) << " fmax should be at least " << largest_f
<< ". f_col cs_B = " << f_col << " " << cs_Born
<< std::endl;
}
f_col = 0.;
f = 0.;
//determine max weight for this vector particle mass
}
if (m > 100000){
if (fmax > 0.) report(Severity::Info,"EvtGen") << "EvtVectorIsr is having problems. Check the fmax value - the 3rd argument in the .dec file\n"
<< "Recommended values for various vector particles: "
<< "phi->1.15 J/psi-psi(4415)->0.105 "
<< "Upsilon(1S,2S,3S)->0.14\n";
assert(0);
}
}//while (fran > f)
}//if (firstorder)
//Compute parameters for boost to/from the system after colinear radiation
double bet_l;
double gam_l;
double betgam_l;
double csfrmn_new;
double csbkmn_new;
if (firstorder){
bet_l = 0.;
gam_l = 1.;
betgam_l = 0.;
csfrmn_new = csfrmn;
csbkmn_new = csbkmn;
} else {
double xx = e02/e01;
double sq_xx = sqrt(xx);
bet_l = (1.-xx)/(1.+xx);
gam_l = (1.+xx)/(2.*sq_xx);
betgam_l = (1.-xx)/(2.*sq_xx);
//Boost photon cos_theta limits in lab to limits in the system after colinear rad
csfrmn_new=(csfrmn - bet_l)/(1. - bet_l*csfrmn);
csbkmn_new=(csbkmn - bet_l)/(1. - bet_l*csbkmn);
}
// //generate kinematics according to Bonneau-Martin article
// //Nucl. Phys. B27 (1971) 381-397
// 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
//gamma momentum in the vpho restframe *after* soft colinear radiation
double pg = (s_new - phi->mass()*phi->mass())/(2.*wcm_new);
//calculate the beta of incoming electrons after colinear rad in the frame where e= and e- have equal momentum
double beta=electMass/ebeam; //electMass/Ebeam = 1/gamma
beta=sqrt(1. - beta*beta); //sqrt (1 - (1/gamma)**2)
double ymax=log((1.+beta*csfrmn_new)/(1.-beta*csfrmn_new));
double ymin=log((1.-beta*csbkmn_new)/(1.+beta*csbkmn_new));
// 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
double phi_p0 = sqrt(phi->mass()*phi->mass()+pg*pg);
double phi_p3 = -pg*cs;
//boost back to frame before colinear radiation.
EvtVector4R p4phi(gam_l*phi_p0 + betgam_l*phi_p3,
-pg*sn*cos(fi),
-pg*sn*sin(fi),
betgam_l*phi_p0 + gam_l*phi_p3);
double isr_p0 = pg;
double isr_p3 = -phi_p3;
EvtVector4R p4gamma(gam_l*isr_p0 + betgam_l*isr_p3,
-p4phi.get(1),
-p4phi.get(2),
betgam_l*isr_p0 + gam_l*isr_p3);
//four-vectors of the collinear photons
if (!firstorder) {
p4softg1.set(0, eb-e02); p4softg1.set(3, e02-eb);
p4softg2.set(0, eb-e01); p4softg2.set(3, eb-e01);
}
//save momenta for particles
phi->init( getDaug(0),p4phi);
gamma->init( getDaug(1),p4gamma);
//add the two colinear photons as vphoton daughters
EvtPhotonParticle *softg1=new EvtPhotonParticle;;
EvtPhotonParticle *softg2=new EvtPhotonParticle;;
softg1->init(gammaId,p4softg1);
softg2->init(gammaId,p4softg2);
softg1->addDaug(p);
softg2->addDaug(p);
//try setting the spin density matrix of the phi
//get polarization vector for phi in its parents restframe.
EvtVector4C phi0=phi->epsParent(0);
EvtVector4C phi1=phi->epsParent(1);
EvtVector4C phi2=phi->epsParent(2);
//get polarization vector for a photon in its parents restframe.
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 ;
}
//======================================================
void EvtBcVNpi::decay( EvtParticle *root_particle ) {
++nCall;
// cout<<"BcVNpi::decay()"<<endl;
root_particle->initializePhaseSpace(getNDaug(),getDaugs());
EvtVector4R
p4b(root_particle->mass(), 0., 0., 0.), // Bc momentum
p4meson=root_particle->getDaug(0)->getP4(), // J/psi momenta
Q=p4b-p4meson;
double Q2=Q.mass2();
// check pi-mesons and calculate hadronic current
EvtVector4C hardCur;
// bool foundHadCurr=false;
if( getNDaug() == 2) {
hardCur = wcurr->WCurrent( root_particle->getDaug(1)->getP4() );
// foundHadCurr=true;
}
else if( getNDaug() == 3) {
hardCur = wcurr->WCurrent( root_particle->getDaug(1)->getP4() ,
root_particle->getDaug(2)->getP4()
);
// foundHadCurr=true;
}
else if( getNDaug() == 4) {
hardCur = wcurr->WCurrent( root_particle->getDaug(1)->getP4() ,
root_particle->getDaug(2)->getP4(),
root_particle->getDaug(3)->getP4()
);
// foundHadCurr=true;
}
else if( getNDaug() == 6) // Bc -> psi pi+ pi+ pi- pi- pi+ from [Kuhn, Was, hep-ph/0602162
{
hardCur = wcurr->WCurrent(root_particle->getDaug(1)->getP4(),
root_particle->getDaug(2)->getP4(),
root_particle->getDaug(3)->getP4(),
root_particle->getDaug(4)->getP4(),
root_particle->getDaug(5)->getP4()
);
// foundHadCurr=true;
}
else {
report(Severity::Error,"EvtGen") << "Have not yet implemented this final state in BCNPI model" << endl;
report(Severity::Error,"EvtGen") << "Ndaug="<<getNDaug() << endl;
int id;
for ( id=0; id<(getNDaug()-1); id++ )
report(Severity::Error,"EvtGen") << "Daug " << id << " "<<EvtPDL::name(getDaug(id)).c_str() << endl;
::abort();
};
// calculate Bc -> V W form-factors
double a1f, a2f, vf, a0f;
double m_meson = root_particle->getDaug(0)->mass();
double m_b = root_particle->mass();
ffmodel->getvectorff(root_particle->getId(),
root_particle->getDaug(0)->getId(),
Q2,
m_meson,
&a1f,
&a2f,
&vf,
&a0f);
double a3f = ((m_b+m_meson)/(2.0*m_meson))*a1f -
((m_b-m_meson)/(2.0*m_meson))*a2f;
// calculate Bc -> V W current
EvtTensor4C H;
H = a1f*(m_b+m_meson)*EvtTensor4C::g();
H.addDirProd((-a2f/(m_b+m_meson))*p4b,p4b+p4meson);
H+=EvtComplex(0.0,vf/(m_b+m_meson))*dual(EvtGenFunctions::directProd(p4meson+p4b,p4b-p4meson));
H.addDirProd((a0f-a3f)*2.0*(m_meson/Q2)*p4b,p4b-p4meson);
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);
};
}