Hello! Dear users, could you tell me what the problem is? I need to switch from the laboratory reference frame to the center of mass system of the virtual photon-proton system. I read the particle data from the file, then calculate their four-vector and with Boost everything should work. But for some reason the angle between the final proton and the photon does not turn out to be 180 degrees.
else if (lineCount % 4 == 3)
{
iss.clear();
iss.seekg(0);
for (int i = 0; i < 3; i++)
{
iss >> dummy;
}
double ID;
iss >> ID;
//std::cout << ID << std::endl;
iss.clear();
iss.seekg(0);
for (int i =0; i < 6; i++)
{
iss >> dummy;
}
iss >> px >> py >> pz;
//std::cout << "px " <<px << "py " << py << "pz " << pz <<std::endl;
iss.clear();
iss.seekg(0);
for (int i =0; i < 9; i++)
{
iss>> dummy;
}
double energy;
iss >> energy;
Ppi.SetPxPyPzE(px, py, pz, energy);
Ppi.Boost(-Pcm.BoostVector());
double theta = TMath::RadToDeg() * Ppi.Theta();
double phi = TMath::RadToDeg() * Ppi.Phi();
energy = Ppi.E();
/*hist1->Fill(energy, phi);
hist2->Fill(energy, theta);
hist3->Fill(theta,phi);*/
}
else if (lineCount % 4 == 0)
{
iss.clear();
iss.seekg(0);
for (int i = 0; i < 3; i++)
{
iss >> dummy;
}
double ID;
iss >> ID;
//std::cout << ID << std::endl;
iss.clear();
iss.seekg(0);
for (int i =0; i < 6; i++)
{
iss >> dummy;
}
iss >> px >> py >> pz;
//std::cout << "px " <<px << "py " << py << "pz " << pz <<std::endl;
iss.clear();
iss.seekg(0);
for (int i =0; i < 9; i++)
{
iss>> dummy;
}
double energy;
iss >> energy;
Pterm.SetPxPyPzE(px, py, pz, energy);
Pterm.Boost(-Pcm.BoostVector());
}
}
file.close();
/*hist1->GetXaxis()->SetTitle("E, GeV");
hist1->GetYaxis()->SetTitle("Phi, °");
hist2->GetXaxis()->SetTitle("E, GeV");
hist2->GetYaxis()->SetTitle("Theta, °");
hist3->GetYaxis()->SetTitle("Phi");
hist3->GetXaxis()->SetTitle("Theta, °");
pad1->cd();
hist1->Draw();
pad2->cd();
hist2->Draw();
pad3->cd();
hist3->Draw();
canvas->SaveAs("pionCM.png");*/
}