Add an optional alpha meson cut Pi0EtaToGammaGamma(MC)

Author: Isabel Kantak

PWGEM/PhotonMeson/Core/Pi0EtaToGammaGamma.h

@@ -70,6 +70,12 @@
 #include <utility>
 #include <vector>
 
+enum AlphaMesonCutOption {
+  Off = 0,
+  SpecificValue = 1,
+  PTDependent = 2
+};
+
 template <o2::aod::pwgem::photonmeson::photonpair::PairType pairtype, o2::soa::is_table... Types>
 struct Pi0EtaToGammaGamma {
   o2::framework::Configurable<std::string> ccdburl{"ccdb-url", "http://alice-ccdb.cern.ch", "url of the ccdb repository"};
@@ -92,6 +98,11 @@ struct Pi0EtaToGammaGamma {
   o2::framework::ConfigurableAxis ConfEPBins{"ConfEPBins", {o2::framework::VARIABLE_WIDTH, -o2::constants::math::PIHalf, -o2::constants::math::PIQuarter, 0.0f, +o2::constants::math::PIQuarter, +o2::constants::math::PIHalf}, "Mixing bins - event plane angle"};
   o2::framework::ConfigurableAxis ConfOccupancyBins{"ConfOccupancyBins", {o2::framework::VARIABLE_WIDTH, -1, 1e+10}, "Mixing bins - occupancy"};
 
+  o2::framework::Configurable<int> cfgAlphaMesonCut{"cfgAlphaMesonCut", 0, "flag for photon energy asymmetry distribution cut: 0: no cut, 1: cut specific value, 2: cut depending on pT"};
+  o2::framework::Configurable<float> cfgAlphaMeson{"cfgAlphaMeson", 0.65, "photon energy asymmetry distribution parameter for specific value cut"};
+  o2::framework::Configurable<float> cfgAlphaMesonA{"cfgAlphaMesonA", 0.65, "photon energy asymmetry distribution parameter A for pT dependent cut"};
+  o2::framework::Configurable<float> cfgAlphaMesonB{"cfgAlphaMesonB", 1.2, "photon energy asymmetry distribution parameter B for pT dependent cut"};
+
   EMPhotonEventCut fEMEventCut;
   struct : o2::framework::ConfigurableGroup {
     std::string prefix = "eventcut_group";
@@ -880,6 +891,25 @@ struct Pi0EtaToGammaGamma {
             continue;
           }
 
+          float alpha_meson = std::fabs(g1.e() -g2.e())/(g1.e() + g2.e());
+          float alpha_cut = 999.f;
+          switch(cfgAlphaMesonCut) {
+            case AlphaMesonCutOption::Off:
+              break;
+            case AlphaMesonCutOption::SpecificValue:
+              alpha_cut = cfgAlphaMeson;
+              break;
+            case AlphaMesonCutOption::PTDependent: {
+              alpha_cut = cfgAlphaMesonA * std::tanh(cfgAlphaMesonB * v12.pt());
+              break;
+            }
+            default:
+              LOGF(error, "Invalid option for alpha meson cut. No alpha cut will be applied.");
+          }
+          if (alpha_meson > alpha_cut) {
+            continue;
+          }
+
           fRegistry.fill(HIST("Pair/same/hs"), v12.M(), v12.Pt(), weight);
 
           if (std::find(used_photonIds_per_col.begin(), used_photonIds_per_col.end(), g1.globalIndex()) == used_photonIds_per_col.end()) {

PWGEM/PhotonMeson/Core/Pi0EtaToGammaGammaMC.h

@@ -65,6 +65,12 @@
 #include <type_traits>
 #include <vector>
 
+enum AlphaMesonCutOption {
+  Off = 0,
+  SpecificValue = 1,
+  PTDependent = 2
+};
+
 template <o2::aod::pwgem::photonmeson::photonpair::PairType pairtype, o2::soa::is_table... Types>
 struct Pi0EtaToGammaGammaMC {
   o2::framework::Configurable<std::string> ccdburl{"ccdb-url", "http://alice-ccdb.cern.ch", "url of the ccdb repository"};
@@ -81,6 +87,11 @@ struct Pi0EtaToGammaGammaMC {
   o2::framework::Configurable<std::string> fd_k0s_to_pi0{"fd_k0s_pi0", "1.0", "feed down correction to pi0"};
   o2::framework::Configurable<bool> cfgRequireTrueAssociation{"cfgRequireTrueAssociation", false, "flag to require true mc collision association"};
 
+  o2::framework::Configurable<int> cfgAlphaMesonCut{"cfgAlphaMesonCut", 0, "flag for photon energy asymmetry distribution cut: 0: no cut, 1: cut specific value, 2: cut depending on pT"};
+  o2::framework::Configurable<float> cfgAlphaMeson{"cfgAlphaMeson", 0.65, "photon energy asymmetry distribution parameter for specific value cut"};
+  o2::framework::Configurable<float> cfgAlphaMesonA{"cfgAlphaMesonA", 0.65, "photon energy asymmetry distribution parameter A for pT dependent cut"};
+  o2::framework::Configurable<float> cfgAlphaMesonB{"cfgAlphaMesonB", 1.2, "photon energy asymmetry distribution parameter B for pT dependent cut"};
+
   EMPhotonEventCut fEMEventCut;
   struct : o2::framework::ConfigurableGroup {
     std::string prefix = "eventcut_group";
@@ -672,6 +683,25 @@ struct Pi0EtaToGammaGammaMC {
             continue;
           }
 
+          float alpha_meson = std::fabs(g1.e() -g2.e())/(g1.e() + g2.e());
+          float alpha_cut = 999.f;
+          switch(cfgAlphaMesonCut) {
+            case AlphaMesonCutOption::Off:
+              break;
+            case AlphaMesonCutOption::SpecificValue:
+              alpha_cut = cfgAlphaMeson;
+              break;
+            case AlphaMesonCutOption::PTDependent: {
+              alpha_cut = cfgAlphaMesonA * std::tanh(cfgAlphaMesonB * v12.pt());
+              break;
+            }
+            default:
+              LOGF(error, "Invalid option for alpha meson cut. No alpha cut will be applied.");
+          }
+          if (alpha_meson > alpha_cut) {
+            continue;
+          }
+
           if (pairtype == o2::aod::pwgem::photonmeson::photonpair::PairType::kEMCEMC) {
             float openingAngle = std::acos(v1.Vect().Dot(v2.Vect()) / (v1.P() * v2.P()));
             if (openingAngle < emccuts.minOpenAngle) {