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#include <memory>
#include "GeneratorInterface/Core/interface/GeneratorFilter.h"
#include "GeneratorInterface/ExternalDecays/interface/ExternalDecayDriver.h"
#include "GeneratorInterface/Pythia8Interface/interface/Py8GunBase.h"
namespace gen {
class Py8PtAndDxyGun : public Py8GunBase {
public:
Py8PtAndDxyGun(edm::ParameterSet const&);
~Py8PtAndDxyGun() override {}
bool generatePartonsAndHadronize() override;
const char* classname() const override;
private:
// PtAndDxyGun particle(s) characteristics
double fMinEta;
double fMaxEta;
double fMinPt;
double fMaxPt;
bool fAddAntiParticle;
double fDxyMin;
double fDxyMax;
double fLxyMax;
double fLzMax;
double fConeRadius;
double fConeH;
double fDistanceToAPEX;
};
// implementation
//
Py8PtAndDxyGun::Py8PtAndDxyGun(edm::ParameterSet const& ps) : Py8GunBase(ps) {
// ParameterSet defpset ;
edm::ParameterSet pgun_params = ps.getParameter<edm::ParameterSet>("PGunParameters"); // , defpset ) ;
fMinEta = pgun_params.getParameter<double>("MinEta"); // ,-2.2);
fMaxEta = pgun_params.getParameter<double>("MaxEta"); // , 2.2);
fMinPt = pgun_params.getParameter<double>("MinPt"); // , 0.);
fMaxPt = pgun_params.getParameter<double>("MaxPt"); // , 0.);
fAddAntiParticle = pgun_params.getParameter<bool>("AddAntiParticle"); //, false) ;
fDxyMin = pgun_params.getParameter<double>("dxyMin");
fDxyMax = pgun_params.getParameter<double>("dxyMax");
fLxyMax = pgun_params.getParameter<double>("LxyMax");
fLzMax = pgun_params.getParameter<double>("LzMax");
fConeRadius = pgun_params.getParameter<double>("ConeRadius");
fConeH = pgun_params.getParameter<double>("ConeH");
fDistanceToAPEX = pgun_params.getParameter<double>("DistanceToAPEX");
}
bool Py8PtAndDxyGun::generatePartonsAndHadronize() {
fMasterGen->event.reset();
int NTotParticles = fPartIDs.size();
if (fAddAntiParticle)
NTotParticles *= 2;
// energy below is dummy, it is not used
(fMasterGen->event).append(990, -11, 0, 0, 2, 1 + NTotParticles, 0, 0, 0., 0., 0., 15000., 15000.);
for (size_t i = 0; i < fPartIDs.size(); i++) {
int particleID = fPartIDs[i]; // this is PDG
double phi = 0;
double dxy = 0;
double pt = 0;
double eta = 0;
double px = 0;
double py = 0;
double pz = 0;
double mass = 0;
double ee = 0;
double vx = 0;
double vy = 0;
double vz = 0;
double lxy = 0;
bool passLoop = false;
while (!passLoop) {
bool passLxy = false;
bool passLz = false;
phi = (fMaxPhi - fMinPhi) * randomEngine().flat() + fMinPhi;
dxy = (fDxyMax - fDxyMin) * randomEngine().flat() + fDxyMin;
float dxysign = randomEngine().flat() - 0.5;
if (dxysign < 0)
dxy = -dxy;
pt = (fMaxPt - fMinPt) * randomEngine().flat() + fMinPt;
px = pt * cos(phi);
py = pt * sin(phi);
for (int i = 0; i < 10000; i++) {
vx = 2 * fLxyMax * randomEngine().flat() - fLxyMax;
vy = (pt * dxy + vx * py) / px;
lxy = sqrt(vx * vx + vy * vy);
if (lxy < std::abs(fLxyMax) && (vx * px + vy * py) > 0) {
passLxy = true;
break;
}
}
eta = (fMaxEta - fMinEta) * randomEngine().flat() + fMinEta;
double theta = 2. * atan(exp(-eta));
mass = (fMasterGen->particleData).m0(particleID);
double pp = pt / sin(theta); // sqrt( ee*ee - mass*mass );
ee = sqrt(pp * pp + mass * mass);
pz = pp * cos(theta);
float coneTheta = fConeRadius / fConeH;
for (int j = 0; j < 100; j++) {
vz = fLzMax * randomEngine().flat(); // this is abs(vz)
float v0 = vz - fDistanceToAPEX;
if (v0 <= 0 || lxy * lxy / (coneTheta * coneTheta) > v0 * v0) {
passLz = true;
break;
}
}
if (pz < 0)
vz = -vz;
passLoop = (passLxy && passLz);
if (passLoop)
break;
}
float time = sqrt(vx * vx + vy * vy + vz * vz);
if (!((fMasterGen->particleData).isParticle(particleID))) {
particleID = std::abs(particleID);
}
if (1 <= std::abs(particleID) && std::abs(particleID) <= 6) // quarks
(fMasterGen->event).append(particleID, 23, 1, 0, 0, 0, 101, 0, px, py, pz, ee, mass);
else if (std::abs(particleID) == 21) // gluons
(fMasterGen->event).append(21, 23, 1, 0, 0, 0, 101, 102, px, py, pz, ee, mass);
// other
else {
(fMasterGen->event).append(particleID, 1, 1, 0, 0, 0, 0, 0, px, py, pz, ee, mass);
int eventSize = (fMasterGen->event).size() - 1;
// -log(flat) = exponential distribution
double tauTmp = -(fMasterGen->event)[eventSize].tau0() * log(randomEngine().flat());
(fMasterGen->event)[eventSize].tau(tauTmp);
}
(fMasterGen->event).back().vProd(vx, vy, vz, time);
// Here also need to add anti-particle (if any)
// otherwise just add a 2nd particle of the same type
// (for example, gamma)
//
if (fAddAntiParticle) {
if (1 <= std::abs(particleID) && std::abs(particleID) <= 6) { // quarks
(fMasterGen->event).append(-particleID, 23, 1, 0, 0, 0, 0, 101, -px, -py, -pz, ee, mass);
} else if (std::abs(particleID) == 21) { // gluons
(fMasterGen->event).append(21, 23, 1, 0, 0, 0, 102, 101, -px, -py, -pz, ee, mass);
} else {
if ((fMasterGen->particleData).isParticle(-particleID)) {
(fMasterGen->event).append(-particleID, 1, 1, 0, 0, 0, 0, 0, -px, -py, -pz, ee, mass);
} else {
(fMasterGen->event).append(particleID, 1, 1, 0, 0, 0, 0, 0, -px, -py, -pz, ee, mass);
}
int eventSize = (fMasterGen->event).size() - 1;
// -log(flat) = exponential distribution
double tauTmp = -(fMasterGen->event)[eventSize].tau0() * log(randomEngine().flat());
(fMasterGen->event)[eventSize].tau(tauTmp);
}
(fMasterGen->event).back().vProd(-vx, -vy, -vz, time);
}
}
if (!fMasterGen->next())
return false;
evtGenDecay();
event() = std::make_unique<HepMC::GenEvent>();
return toHepMC.fill_next_event(fMasterGen->event, event().get());
}
const char* Py8PtAndDxyGun::classname() const { return "Py8PtAndDxyGun"; }
typedef edm::GeneratorFilter<gen::Py8PtAndDxyGun, gen::ExternalDecayDriver> Pythia8PtAndDxyGun;
} // namespace gen
using gen::Pythia8PtAndDxyGun;
DEFINE_FWK_MODULE(Pythia8PtAndDxyGun);
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