//________________________________________________________
void KVParticle::SetRandomMomentum(Double_t T, Double_t thmin,
Double_t thmax, Double_t phmin,
Double_t phmax, Option_t* opt)
{
//Give randomly directed momentum to particle with kinetic energy T
//Direction will be between (thmin,thmax) [degrees] limits in polar angle,
//and (phmin,phmax) [degrees] limits in azimuthal angle.
//
//If opt = "" or "isotropic" (default) : direction is isotropically distributed over the solid angle
//If opt = "random" : direction is randomly distributed over solid angle
//
//Based on KVPosition::GetRandomDirection().
Double_t p = (T + M()) * (T + M()) - M2();
if (p > 0.)
p = (TMath::Sqrt(p)); // calculate momentum
else
p = 0.;
TVector3 dir;
KVPosition pos(thmin, thmax, phmin, phmax);
dir = pos.GetRandomDirection(opt); // get isotropic unit vector dir
if (p && dir.Mag())
dir.SetMag(p); // set magnitude of vector to momentum required
SetMomentum(dir); // set momentum 4-vector
}
int main( int argc, const char *argv[] )
{
double momentum = 0.2;
double theta = 0.5*M_PI;
double phi = 0.00;
double M = 10.0;
double Energy = sqrt(momentum*momentum+M*M);
double m1 = 0.0000;
double m2 = 0.0000;
double m3 = 0.0000;
// double x1 = 0.5;
// double x2 = 0.2;
// double x3 = 0.4;
// double x4 = 0.3342;
// double x5 = 0.75;
//
double x1 = 0.50;
double x2 = 0.00;
double x3 = 0.00;
double x4 = 0.00;
double x5 = 0.00;
{
std::cout << "test_PhaseSpaceTools " << std::endl;
TLorentzVector p1;
TLorentzVector p2;
TLorentzVector p3;
TVector3 v1;
double costheta1 = 2*x2-1;
double sintheta1 = sqrt(1-costheta1*costheta1);
double phi1 = 2*M_PI*x3;
double sqrt_s23 = x1*(M-m1-m2-m3) + m1+m2;
double costheta23 = 2*x4-1;
double sintheta23 = sqrt(1-costheta23*costheta23);
double phi23 = 2*M_PI*x5;
double s = M*M;
double m1_sqr = m1*m1;
double m2_sqr = m2*m2;
double m3_sqr = m3*m3;
double s23 = sqrt_s23*sqrt_s23;
double pmag = TwoBodyFunc::p (s, m1_sqr, s23);
double beta1 = TwoBodyFunc::beta (s, m1_sqr, s23);
double E1 = TwoBodyFunc::E (M, m1_sqr, s23);
double E23 = TwoBodyFunc::E (M, s23, m1_sqr);
p1.SetPxPyPzE(pmag*sintheta1*cos(phi1),pmag*sintheta1*sin(phi1),pmag*costheta1,E1);
TVector3 v;
v = -p1.Vect();
v.SetMag(v.Mag()/E23);
double p2mag = TwoBodyFunc::p (s23, m2_sqr, m3_sqr);
double E2 = TwoBodyFunc::E (sqrt_s23, m2_sqr, m3_sqr);
double E3 = TwoBodyFunc::E (sqrt_s23, m3_sqr, m2_sqr);
p2.SetPxPyPzE(p2mag*sintheta23*cos(phi23),p2mag*sintheta23*sin(phi23),p2mag*costheta23,E2);
p3.SetPxPyPzE(-p2mag*sintheta23*cos(phi23),-p2mag*sintheta23*sin(phi23),-p2mag*costheta23,E3);
std::cout << "p1:" << std::endl;
displayTLorentzVector(&p1);
std::cout << "p2 and p3 in the 23 rest frame:" << std::endl;
std::cout << "p2:" << std::endl;
displayTLorentzVector(&p2);
std::cout << "p3:" << std::endl;
displayTLorentzVector(&p3);
p2.Boost(v);
p3.Boost(v);
std::cout << "All in the lab frame:" << std::endl;
std::cout << "p1:" << std::endl;
displayTLorentzVector(&p1);
std::cout << "p2:" << std::endl;
displayTLorentzVector(&p2);
std::cout << "p3:" << std::endl;
displayTLorentzVector(&p3);
TLorentzVector sum;
sum = p1 + p2 + p3;
std::cout << "sum in the lab frame:" << std::endl;
displayTLorentzVector(&sum);
}
{
printf("######################################\n");
printf("### --- TwoBudyFunc utils TEST --- ###\n");
printf("######################################\n");
double M_test = 5.0;
double m1_sqr_test = 3.0;
double m2_sqr_test = 1.0;
double E = TwoBodyFunc::E (M_test, m1_sqr_test, m2_sqr_test);
printf("M_test: %.2f\n", M_test);
printf("m1_sqr_test: %.2f\n", m1_sqr_test);
printf("m2_sqr_test: %.2f\n", m2_sqr_test);
printf("TwoBodyFunc::E (M_test, m1_sqr_test, m2_sqr_test): %.2f\n", E);
}
{
printf("\n");
printf("########################################\n");
printf("### --- ThreeBodyDecayClass TEST --- ###\n");
printf("########################################\n");
printf("\n");
// ThreeBodyDecay class
ThreeBodyDecay tau(M, m1, m2, m3);
tau.SetMotherMPThetaPhi(M,momentum,theta,phi);
tau.SetBitBoostBack(true);
tau.SetPhaseSpace(x1, x2, x3, x4, x5);
TLorentzVector *P = tau.P;
TLorentzVector *p1 = tau.p[0];
TLorentzVector *p2 = tau.p[1];
TLorentzVector *p3 = tau.p[2];
double amp = P->Dot( (*p3) ) * p1->Dot( (*p2) );
tau.DisplayAll();
// printf("\ns23_min: %.2f", );
double weight = tau.GetPhaseSpaceWeight(x1, x2, x3, x4, x5);
std::cout << "PSWeight: " << weight << std::endl;
std::cout << "amp: " << amp << std::endl;
std::cout << "P:" << std::endl;
displayTLorentzVector(P);
std::cout << "p1:" << std::endl;
displayTLorentzVector(p1);
std::cout << "p2:" << std::endl;
displayTLorentzVector(p2);
std::cout << "p3:" << std::endl;
displayTLorentzVector(p3);
TLorentzVector sum = (*p1) + (*p2) + (*p3);
std::cout << "p1+p2+p3:" << std::endl;
displayTLorentzVector(&sum);
}
}
