Add generator for LambdaB --> nuclei

MC/config/PWGHF/ini/GeneratorHFTrigger_LambdaBToNuclei.ini

@@ -0,0 +1,7 @@
+### The external generator derives from GeneratorPythia8.
+[GeneratorExternal]
+fileName=${O2DPG_MC_CONFIG_ROOT}/MC/config/PWGHF/external/generator/generator_pythia8_hfhadron_to_nuclei.C
+funcName=generateHFHadToNuclei(3, {5122}, {1000020030, 1000010030}, true, 0.5)
+
+[GeneratorPythia8]
+config=${O2DPG_MC_CONFIG_ROOT}/MC/config/PWGHF/pythia8/generator/pythia8_lambdab_with_decays_Mode2.cfg

MC/config/PWGHF/ini/tests/GeneratorHFTrigger_LambdaBToNuclei.C

@@ -0,0 +1,56 @@
+int External()
+{
+    std::string path{"o2sim_Kine.root"};
+    std::vector<int> checkPdgHadron{5122};                 // Lambda_b
+    std::vector<int> nucleiDauPdg{1000020030, 1000010030}; // 3He, 3H
+
+    TFile file(path.c_str(), "READ");
+    if (file.IsZombie())
+    {
+        std::cerr << "Cannot open ROOT file " << path << "\n";
+        return 1;
+    }
+
+    auto tree = (TTree *)file.Get("o2sim");
+    std::vector<o2::MCTrack> *tracks{};
+    tree->SetBranchAddress("MCTrack", &tracks);
+
+    int nSignals{}, nSignalGoodDecay{};
+    auto nEvents = tree->GetEntries();
+
+    for (int i = 0; i < nEvents; i++)
+    {
+        tree->GetEntry(i);
+        for (auto &track : *tracks)
+        {
+            auto pdg = track.GetPdgCode();
+            if (std::find(checkPdgHadron.begin(), checkPdgHadron.end(), std::abs(pdg)) != checkPdgHadron.end()) // found signal
+            {
+                // count signal PDG
+                if(std::abs(track.GetRapidity()) > 1.5) continue; // skip if outside rapidity window
+                nSignals++;
+                for (int j{track.getFirstDaughterTrackId()}; j <= track.getLastDaughterTrackId(); ++j)
+                {
+                    auto pdgDau = tracks->at(j).GetPdgCode();
+                    if (std::find(nucleiDauPdg.begin(), nucleiDauPdg.end(), std::abs(pdgDau)) != nucleiDauPdg.end())
+                    {
+                        nSignalGoodDecay++;
+                    }
+                }
+            }
+        }
+    }
+    std::cout << "--------------------------------\n";
+    std::cout << "# Events: " << nEvents << "\n";
+    std::cout <<"# signal hadrons: " << nSignals << "\n";
+    std::cout <<"# signal hadrons decaying into nuclei: " << nSignalGoodDecay << "\n";
+
+    float fracForcedDecays = float(nSignalGoodDecay) / nSignals;
+    if (fracForcedDecays < 0.8) // we put some tolerance (lambdaB in MB events do not coalesce)
+    {
+        std::cerr << "Fraction of signals decaying into nuclei: " << fracForcedDecays << ", lower than expected\n";
+        return 1;
+    }
+
+    return 0;
+}

MC/config/PWGHF/pythia8/generator/pythia8_lambdab_with_decays_Mode2.cfg

@@ -0,0 +1,73 @@
+### authors: Fabrizio Grosa (fabrizio.grosa@cern.ch)
+###          Cristina Terrevoli (cristina.terrevoli@cern.ch)
+###          Fabio Catalano (fabio.catalano@cern.ch)
+### last update:  November 2023
+
+### beams
+Beams:idA 2212			# proton
+Beams:idB 2212 			# proton
+Beams:eCM 13600. 		# GeV
+
+### processes
+SoftQCD:inelastic on		# all inelastic processes
+
+### decays
+ParticleDecays:limitTau0 on	
+ParticleDecays:tau0Max 10.
+
+### switching on Pythia Mode2
+ColourReconnection:mode 1
+ColourReconnection:allowDoubleJunRem off
+ColourReconnection:m0 0.3
+ColourReconnection:allowJunctions on
+ColourReconnection:junctionCorrection 1.20
+ColourReconnection:timeDilationMode 2
+ColourReconnection:timeDilationPar 0.18
+StringPT:sigma 0.335
+StringZ:aLund 0.36
+StringZ:bLund 0.56
+StringFlav:probQQtoQ 0.078
+StringFlav:ProbStoUD 0.2
+StringFlav:probQQ1toQQ0join 0.0275,0.0275,0.0275,0.0275
+MultiPartonInteractions:pT0Ref 2.15
+BeamRemnants:remnantMode 1
+BeamRemnants:saturation 5
+
+# Correct decay lengths (wrong in PYTHIA8 decay table)
+# Lb
+5122:tau0 = 0.4390
+# Xic0
+4132:tau0 = 0.0455
+# OmegaC
+4332:tau0 = 0.0803
+
+## Lb decay modes
+5122:onMode = off
+5122:oneChannel = 1 9.03e-05  0 2212 2212 -2212 -2212 2112  
+5122:addChannel = 1 0.00181  0 2212 2212 -2212 -2212 2112 111  
+5122:addChannel = 1 0.0181  0 2212 2212 -2212 -2212 2112 111 111  
+5122:addChannel = 1 0.0271  0 2212 2212 -2212 -2212 2112 211 -211  
+5122:addChannel = 1 0.0181  0 2212 2212 -2212 -2212 2112 211 211 -211 -211  
+5122:addChannel = 1 0.181  0 2212 2212 -2212 -2212 2112 211 -211 111  
+5122:addChannel = 1 0.199  0 2212 2212 -2212 -2212 2112 211 -211 111 111  
+5122:addChannel = 1 0.0271  0 2212 2212 -2212 -2212 2112 211 211 -211 -211 111  
+5122:addChannel = 1 0.00452  0 2212 2212 -2212 -2212 2112 211 111  
+5122:addChannel = 1 0.0361  0 2212 2212 2112 -2212 -2112 -211 111  
+5122:addChannel = 1 0.0452  0 2212 2212 2112 -2212 -2112 -211 111 111  
+5122:addChannel = 1 0.0542  0 2212 2212 2112 -2212 -2112 -211 -211 211  
+5122:addChannel = 1 0.361  0 2212 2212 2112 -2212 -2112 -211 -211 211 111  
+5122:addChannel = 1 0.0271  0 2212 2212 2112 -2212 -2112 -211 -211 211 111 111  
+5122:onIfMatch = 2212 2212 2212 2212 2112 
+5122:onIfMatch = 2212 2212 2212 2212 2112 111 
+5122:onIfMatch = 2212 2212 2212 2212 2112 111 111 
+5122:onIfMatch = 2212 2212 2212 2212 2112 211 211 
+5122:onIfMatch = 2212 2212 2212 2212 2112 211 211 211 211 
+5122:onIfMatch = 2212 2212 2212 2212 2112 211 211 111 
+5122:onIfMatch = 2212 2212 2212 2212 2112 211 211 111 111 
+5122:onIfMatch = 2212 2212 2212 2212 2112 211 211 211 211 111 
+5122:onIfMatch = 2212 2212 2212 2212 2112 211 111 
+5122:onIfMatch = 2212 2212 2112 2212 2112 211 111 
+5122:onIfMatch = 2212 2212 2112 2212 2112 211 111 111 
+5122:onIfMatch = 2212 2212 2112 2212 2112 211 211 211 
+5122:onIfMatch = 2212 2212 2112 2212 2112 211 211 211 111 
+5122:onIfMatch = 2212 2212 2112 2212 2112 211 211 211 111 111