Add optional PCM material-budget weights in PCMPCM

Add a V0 photon material-budget weight table (Omega MB weights) and join it
in the PCMPCM pi0/eta workflow. The weights are applied only when the joined
column is available, using compile-time guarded access.

Introduce a configurable switch (runWithMBWeights) in MaterialBudgetWeights:
- false: no CCDB query, write weight=1
- true: require CCDB histogram and abort if missing

Author: Youssef El Mard Bouziani

PWGEM/PhotonMeson/Core/Pi0EtaToGammaGamma.h

@@ -227,7 +227,9 @@ struct Pi0EtaToGammaGamma {
   //---------------------------------------------------------------------------
   // Preslices and partitions
   o2::framework::SliceCache cache;
-  o2::framework::PresliceOptional<o2::soa::Filtered<o2::soa::Join<o2::aod::V0PhotonsKF, o2::aod::V0KFEMEventIds, o2::aod::V0PhotonsKFPrefilterBitDerived>>> perCollision_pcm = o2::aod::v0photonkf::emeventId;
+  o2::framework::PresliceOptional<
+  o2::soa::Filtered<
+  o2::soa::Join<o2::aod::V0PhotonsKF, o2::aod::V0KFEMEventIds, o2::aod::V0PhotonsKFPrefilterBitDerived, o2::aod::V0PhotonOmegaMBWeights>>> perCollision_pcm = o2::aod::v0photonkf::emeventId;
   o2::framework::PresliceOptional<o2::soa::Join<o2::aod::EmEmcClusters, o2::aod::EMCEMEventIds>> perCollision_emc = o2::aod::emccluster::emeventId;
   o2::framework::PresliceOptional<o2::soa::Join<o2::aod::PHOSClusters, o2::aod::PHOSEMEventIds>> perCollision_phos = o2::aod::phoscluster::emeventId;
   o2::framework::PresliceOptional<o2::soa::Filtered<o2::soa::Join<o2::aod::EMPrimaryElectronsFromDalitz, o2::aod::EMPrimaryElectronEMEventIds, o2::aod::EMPrimaryElectronsPrefilterBitDerived>>> perCollision_electron = o2::aod::emprimaryelectron::emeventId;
@@ -878,7 +880,16 @@ struct Pi0EtaToGammaGamma {
             continue;
           }
 
-          fRegistry.fill(HIST("Pair/same/hs"), v12.M(), v12.Pt(), weight);
+          float wpair = weight;
+
+          if constexpr (requires { g1.omegaMBWeight(); }) {
+            wpair *= g1.omegaMBWeight();
+          }
+          if constexpr (requires { g2.omegaMBWeight(); }) {
+            wpair *= g2.omegaMBWeight();
+          }
+
+          fRegistry.fill(HIST("Pair/same/hs"), v12.M(), v12.Pt(), wpair);
 
           if (std::find(used_photonIds_per_col.begin(), used_photonIds_per_col.end(), g1.globalIndex()) == used_photonIds_per_col.end()) {
             emh1->AddTrackToEventPool(key_df_collision, o2::aod::pwgem::dilepton::utils::EMTrack(g1.pt(), g1.eta(), g1.phi(), 0));

PWGEM/PhotonMeson/DataModel/gammaTables.h

@@ -682,6 +682,17 @@ DECLARE_SOA_INDEX_COLUMN_FULL(Cell, cell, int, Calos, "");                 //! r
 DECLARE_SOA_TABLE(SkimEMCCells, "AOD", "SKIMEMCCELLS",                        //! table of link between skimmed EMCal clusters and their cells
                   o2::soa::Index<>, caloextra::ClusterId, caloextra::CellId); //!
 using SkimEMCCell = SkimEMCCells::iterator;
+
+namespace v0photonMBweights
+{
+DECLARE_SOA_COLUMN(OmegaMBWeight, omegaMBWeight, float);
+}
+
+DECLARE_SOA_TABLE(V0PhotonOmegaMBWeights, "AOD", "V0PHOTONMBW", v0photonMBweights::OmegaMBWeight); // store MB weights. To be joined with V0PhotonsKF table at analysis level.
+
+using V0PhotonOmegaMBWeight = V0PhotonOmegaMBWeights::iterator; 
 } // namespace o2::aod
 
+
+
 #endif // PWGEM_PHOTONMESON_DATAMODEL_GAMMATABLES_H_

PWGEM/PhotonMeson/TableProducer/CMakeLists.txt

@@ -63,3 +63,8 @@ o2physics_add_dpl_workflow(skimmer-dalitz-ee
                     SOURCES skimmerDalitzEE.cxx
                     PUBLIC_LINK_LIBRARIES O2::Framework O2Physics::AnalysisCore
                     COMPONENT_NAME Analysis)
+
+o2physics_add_dpl_workflow(material-budget-weights
+                    SOURCES materialBudgetWeights.cxx
+                    PUBLIC_LINK_LIBRARIES O2::Framework O2Physics::AnalysisCore O2::CCDB ROOT::Hist ROOT::Core
+                    COMPONENT_NAME Analysis)

PWGEM/PhotonMeson/TableProducer/materialBudgetWeights.cxx

@@ -0,0 +1,27 @@
+// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
+// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+// All rights not expressly granted are reserved.
+//
+// This software is distributed under the terms of the GNU General Public
+// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+//
+// In applying this license CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+///
+/// \file MaterialBudgetWeights.h
+///
+/// \brief This code produces a table to retrieve material budget weights. The table is to be join with V0PhotonKF
+///
+/// \author Youssef El Mard (youssef.el.mard.bouziani@cern.ch)
+
+
+#include "PWGEM/PhotonMeson/Utils/MaterialBudgetWeights.h"
+#include "Framework/runDataProcessing.h"
+
+using namespace o2::framework;
+
+WorkflowSpec defineDataProcessing(ConfigContext const& cfgc)
+{
+  return WorkflowSpec{adaptAnalysisTask<MaterialBudgetWeights>(cfgc)};
+}

PWGEM/PhotonMeson/Tasks/Pi0EtaToGammaGammaPCMPCM.cxx

@@ -16,6 +16,7 @@
 #include "PWGEM/PhotonMeson/Core/Pi0EtaToGammaGamma.h"
 #include "PWGEM/PhotonMeson/DataModel/gammaTables.h"
 #include "PWGEM/PhotonMeson/Utils/PairUtilities.h"
+#include "PWGEM/PhotonMeson/Utils/MaterialBudgetWeights.h"
 
 #include <Framework/AnalysisDataModel.h>
 #include <Framework/AnalysisTask.h>
@@ -26,11 +27,12 @@ using namespace o2::aod;
 using namespace o2::framework;
 using namespace o2::aod::pwgem::photonmeson::photonpair;
 
-using MyV0Photons = o2::soa::Filtered<o2::soa::Join<o2::aod::V0PhotonsKF, o2::aod::V0KFEMEventIds, o2::aod::V0PhotonsKFPrefilterBitDerived>>;
+using MyV0Photons = o2::soa::Filtered<o2::soa::Join<o2::aod::V0PhotonsKF, o2::aod::V0KFEMEventIds, o2::aod::V0PhotonsKFPrefilterBitDerived, o2::aod::V0PhotonOmegaMBWeights>>;
 
 WorkflowSpec defineDataProcessing(ConfigContext const& cfgc)
 {
   return WorkflowSpec{
+    adaptAnalysisTask<MaterialBudgetWeights>(cfgc),
     adaptAnalysisTask<Pi0EtaToGammaGamma<PairType::kPCMPCM, MyV0Photons, aod::V0Legs>>(cfgc, TaskName{"pi0eta-to-gammagamma-pcmpcm"}),
   };
 }

PWGEM/PhotonMeson/Utils/MaterialBudgetWeights.h

@@ -0,0 +1,95 @@
+// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
+// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+// All rights not expressly granted are reserved.
+//
+// This software is distributed under the terms of the GNU General Public
+// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+//
+// In applying this license CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+///
+/// \file materialBudgetWeights.cxx
+///
+/// \brief This code produces a table to retrieve material budget weights. The table is to be join with V0PhotonKF
+///
+/// \author Youssef El Mard (youssef.el.mard.bouziani@cern.ch)
+///
+
+#ifndef PWGEM_PHOTONMESON_UTILS_MATERIALBUDGETWEIGHTS_H_
+#define PWGEM_PHOTONMESON_UTILS_MATERIALBUDGETWEIGHTS_H_
+
+#include "PWGEM/PhotonMeson/DataModel/gammaTables.h"
+#include <CCDB/BasicCCDBManager.h>
+
+#include "Framework/ASoAHelpers.h"
+#include "Framework/AnalysisDataModel.h"
+#include "Framework/AnalysisTask.h"
+#include "Framework/Logger.h"
+#include <Framework/Configurable.h>
+#include <Framework/InitContext.h>
+
+
+using namespace o2;
+using namespace o2::soa;
+using namespace o2::framework;
+
+using MyV0PhotonsMB = o2::soa::Join<o2::aod::V0PhotonsKF, o2::aod::V0KFEMEventIds>;
+using MyV0PhotonMB  = MyV0PhotonsMB::iterator;
+
+struct MaterialBudgetWeights {
+  Produces<aod::V0PhotonOmegaMBWeights> omegaMBWeight;
+
+  Configurable<std::string> ccdbUrl{"ccdbUrl", "http://ccdb-test.cern.ch:8080", "CCDB url"};
+  Configurable<std::string> mbWeightsPath{"mbWeightsPath", "Users/y/yelmard/MaterialBudget/OmegaMBWeights", "Path of the mb weights"};
+  Configurable<bool> runWithMBWeights{"runWithMBWeights", false, "Run task using material-budget weights for PCM photons"};
+
+  o2::ccdb::CcdbApi ccdbApi;
+  TH1F* hOmegaMBFromCCDB = nullptr;
+
+  void init(InitContext&)
+  {
+    if (!runWithMBWeights) {
+      LOG(info) << "MaterialBudgetWeights: runWithMBWeights=false -> no CCDB query, will write weight=1";
+      return;
+    }
+
+    ccdbApi.init(ccdbUrl.value);
+    std::map<std::string, std::string> metadata;
+    LOG(info) << "MaterialBudgetWeights: loading Omega MB histogram from CCDB at path: " << mbWeightsPath.value;
+
+    hOmegaMBFromCCDB = ccdbApi.retrieveFromTFileAny<TH1F>(mbWeightsPath, metadata, -1);
+
+    if (!hOmegaMBFromCCDB) {
+      LOG(fatal) << "MaterialBudgetWeights: runWithMBWeights=true but CCDB object is missing. Path=" << mbWeightsPath.value;
+    }
+  }
+
+  float computeMBWeight(float v0Rxy)
+  {
+    if (!hOmegaMBFromCCDB) {
+      LOG(fatal) << "MaterialBudgetWeights: internal error: histogram nullptr while runWithMBWeights=true";
+    }
+
+    int binMBWeight = hOmegaMBFromCCDB->FindBin(v0Rxy);
+    if (binMBWeight < 1 || binMBWeight > hOmegaMBFromCCDB->GetNbinsX()) {
+      LOG(debug) << "MaterialBudgetWeights: v0Rxy out of histogram range, returning 1";
+      return 1.f;
+    }
+
+    return hOmegaMBFromCCDB->GetBinContent(binMBWeight);
+  }
+
+  void process(MyV0PhotonMB const& v0)
+  {
+    if (!runWithMBWeights) {
+      omegaMBWeight(1.f);
+      return;
+    }
+
+    omegaMBWeight(computeMBWeight(v0.v0radius()));
+  }
+};
+
+
+#endif // PWGEM_PHOTONMESON_UTILS_MATERIALBUDGETWEIGHTS_H_