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Keep track of resonance intermediate state in coalescence #2379

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Merged
fgrosa merged 1 commit into from
Jun 11, 2026
+9 −4
Merged

Keep track of resonance intermediate state in coalescence #2379

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13 changes: 9 additions & 4 deletions MC/config/PWGHF/external/generator/generator_pythia8_embed_charmnuclei.C
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Original file line number Diff line number Diff line change
Expand Up @@ -170,7 +170,8 @@ class GeneratorPythia8HFEmbedCharmNuclei : public o2::eventgen::GeneratorPythia8
mPythiaGun.moreDecays();
std::array<int, 2> dausToCoal = {-1, -1};
std::vector<int> pdgShortLivedResos = {313, 2224, 102134};
bool isResoFound{false};
std::map<int, int> statusResoDecay = {{313, 95}, {2224, 96}, {102134, 97}}; // do not use 94, it is used by default for no resonances
int whichReso{0};
int idxCharmNucleus{-1};
for (int iPart{0}; iPart<mPythiaGun.event.size(); ++iPart) {
auto part = mPythiaGun.event[iPart];
Expand All @@ -180,17 +181,18 @@ class GeneratorPythia8HFEmbedCharmNuclei : public o2::eventgen::GeneratorPythia8
}
auto mother = part.mother1();
// if we find a resonance, we remove it, otherwise we prevent the coalescence of daughters from resonances and daughters from charmed nucleus directly
if (std::find(pdgShortLivedResos.begin(), pdgShortLivedResos.end(), absPdg) != pdgShortLivedResos.end() && mother >= idxCharmNucleus) {
auto resoIt = std::find(pdgShortLivedResos.begin(), pdgShortLivedResos.end(), absPdg);
if (resoIt != pdgShortLivedResos.end() && mother >= idxCharmNucleus) {
// we need to change the indices of the daughter particles to point to the charmed nucleus
auto dauList = part.daughterList();
for (auto const& dau : dauList) {
mPythiaGun.event[dau].mother1(idxCharmNucleus);
}
mPythiaGun.event.remove(iPart, iPart, true);
isResoFound=true;
whichReso=*resoIt;
}
}
if (isResoFound) { // we have to reset all the particles as daughters of the charm nucleus
if (whichReso > 0) { // we have to reset all the particles as daughters of the charm nucleus
std::vector<int> idxDausCharmNucleus{};
for (int iPart{0}; iPart<mPythiaGun.event.size(); ++iPart) {
auto mother = mPythiaGun.event[iPart].mother1();
Expand Down Expand Up @@ -242,6 +244,9 @@ class GeneratorPythia8HFEmbedCharmNuclei : public o2::eventgen::GeneratorPythia8

// we try the coalescence here, if successful we copy particles in the pythia event and we move to the next charm nucleus
isCoalSuccess = CoalescencePythia8(mPythiaGun.event, std::vector<unsigned int>{1000010020}, mTrivialCoal, mCoalMomentum, dausToCoal[0], dausToCoal[1], 10.);
if (whichReso > 0) {
mPythiaGun.event[idxCharmNucleus].status(statusResoDecay[whichReso]);
}
if (isCoalSuccess) {
restoreEnergyConservation(mPythiaGun.event, idxCharmNucleus);
int offset = mPythia.event.size(); // we need to rescale the indices of mothers and daughters, accounting for the particles that are already appended to the event
Expand Down
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