[PWGLF] Add systematic mapping analysis task (AliceO2Group#13075)

- add prototask

Author: njacazio

PWGLF/Tasks/QC/CMakeLists.txt

@@ -138,4 +138,9 @@ o2physics_add_dpl_workflow(its-tpc-matching-vzeros
 o2physics_add_dpl_workflow(v0assoqa
     SOURCES v0assoqa.cxx
     PUBLIC_LINK_LIBRARIES O2Physics::AnalysisCore O2::DCAFitter KFParticle::KFParticle O2Physics::TPCDriftManager
+    COMPONENT_NAME Analysis)
+
+o2physics_add_dpl_workflow(systematics-mapping
+    SOURCES systematicsMapping.cxx
+    PUBLIC_LINK_LIBRARIES O2Physics::AnalysisCore
     COMPONENT_NAME Analysis)

PWGLF/Tasks/QC/systematicsMapping.cxx

@@ -0,0 +1,152 @@
+// 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 systematicsMapping.cxx
+/// \brief Task to perform a systematics study for K0s and charged Kaons
+/// \author Nicolò Jacazio, Universita del Piemonte Orientale (IT)
+/// \since September 22, 2025
+
+#include "PWGLF/DataModel/LFStrangenessTables.h"
+
+#include "Common/DataModel/EventSelection.h"
+#include "Common/DataModel/PIDResponseTOF.h"
+#include "Common/DataModel/PIDResponseTPC.h"
+
+#include <Framework/AnalysisDataModel.h>
+#include <Framework/AnalysisTask.h>
+#include <Framework/HistogramRegistry.h>
+#include <Framework/runDataProcessing.h>
+#include <ReconstructionDataFormats/Track.h>
+
+#include <algorithm>
+
+using namespace o2;
+using namespace o2::framework;
+
+struct SystematicsMapping {
+  // Returns a unique index for the combination of cuts
+  ConfigurableAxis ptBins{"ptBins", {100, 0.f, 10.f}, "Binning for pT (GeV/c)"};
+  ConfigurableAxis etaBins{"etaBins", {40, -1.0f, 1.0f}, "Binning for #eta"};
+  ConfigurableAxis phiBins{"phiBins", {36, 0.f, o2::constants::math::TwoPI}, "Binning for #phi (rad)"};
+  // Define the Signal axis
+  ConfigurableAxis invariantMassBins{"invariantMassBins", {100, -0.1f, 0.1f}, "Binning for the invariant mass (GeV/c^2)"};
+  ConfigurableAxis nsigmaBins{"nsigmaBins", {100, -10.f, 10.f}, "Binning for nSigma"};
+  // Selection bins
+  ConfigurableAxis tpcClusterBins{"tpcClusterBins", {5, 70, 100, 120, 135, 150}, "Min TPC clusters for tracks"};
+  ConfigurableAxis itsClustersBins{"itsClustersBins", {5, 0, 6}, "Min ITS clusters for tracks"};
+  // Selection configurables
+  Configurable<float> selectionPosZ{"selectionPosZ", 10.f, "Max |z| of the primary vertex"};
+
+  HistogramRegistry registry{"registry"};
+
+  template <typename T>
+  bool isCollisionSelected(T const& collision)
+  {
+    return collision.sel8() && std::abs(collision.posZ()) <= selectionPosZ;
+  }
+
+  void init(InitContext const&)
+  {
+    const AxisSpec ptAxis{ptBins, "#it{p}_{T} (GeV/c)"};
+    const AxisSpec etaAxis{etaBins, "#eta"};
+    const AxisSpec phiAxis{phiBins, "#phi (rad)"};
+
+    if (doprocessData) {
+
+      // First we define the histograms on which we are cutting (tpc clusters, its clusters, ..)
+      registry.add("K/hTPCClusters", "", HistType::kTH1F, {{100, 0, 200}});
+      registry.add("K/hITSClusters", "", HistType::kTH1F, {{10, 0, 10}});
+      registry.addClone("K/", "K0s/");
+
+      // Add the signal histograms
+      registry.add("K/SignalPositive", "", HistType::kTHnSparseF, {ptBins, etaBins, phiBins, nsigmaBins, tpcClusterBins, itsClustersBins});
+      registry.add("K/SignalNegative", "", HistType::kTHnSparseF, {ptBins, etaBins, phiBins, nsigmaBins, tpcClusterBins, itsClustersBins});
+      registry.add("K0s/Signal", "", HistType::kTHnSparseF, {ptBins, etaBins, phiBins, invariantMassBins, tpcClusterBins, itsClustersBins});
+    }
+
+    if (doprocessMc) {
+      registry.add("K/GeneratedPositive", "", HistType::kTHnSparseF, {ptBins, etaBins, phiBins});
+      registry.add("K/GeneratedNegative", "", HistType::kTHnSparseF, {ptBins, etaBins, phiBins});
+      registry.add("K0s/Generated", "", HistType::kTHnSparseF, {ptBins, etaBins, phiBins});
+    }
+  }
+
+  using TrackType = soa::Join<aod::Tracks, aod::TracksExtra, aod::pidTPCFullKa, aod::pidTOFFullPi>;
+  using CollisionType = soa::Join<aod::Collisions, aod::EvSels>;
+
+  void processData(CollisionType const& collisions,
+                   TrackType const& tracks,
+                   aod::V0Datas const& v0s)
+  {
+    for (const auto& collision : collisions) {
+      if (isCollisionSelected(collision))
+        continue; // MB selection
+
+      // Kaon loop
+      for (const auto& track : tracks) {
+        if (track.collisionId() != collision.globalIndex())
+          continue;
+        registry.fill(HIST("hTPCClusters"), track.tpcNClsFound());
+        registry.fill(HIST("hITSClusters"), track.itsNCls());
+        if (track.sign() > 0)
+          registry.fill(HIST("K/SignalPositive"), track.pt(), track.eta(), track.phi(), track.tpcNSigmaKa(), track.tpcNClsFound(), track.itsNCls());
+        else
+          registry.fill(HIST("K/SignalNegative"), track.pt(), track.eta(), track.phi(), track.tpcNSigmaKa(), track.tpcNClsFound(), track.itsNCls());
+      }
+
+      // K0s loop
+      for (const auto& v0 : v0s) {
+        if (v0.collisionId() != collision.globalIndex())
+          continue;
+        const auto& posTrack = v0.posTrack_as<TrackType>();
+        const auto& negTrack = v0.negTrack_as<TrackType>();
+        registry.fill(HIST("K0s/Signal"), v0.pt(), v0.eta(), v0.phi(), v0.mK0Short() - constants::physics::MassK0Short, std::min(posTrack.tpcNClsFound(), negTrack.tpcNClsFound()), std::min(posTrack.itsNCls(), negTrack.itsNCls()));
+      }
+    }
+  }
+  PROCESS_SWITCH(SystematicsMapping, processData, "Systematics study for K0s and charged Kaons", true);
+
+  void processMc(soa::Join<CollisionType, aod::McCollisionLabels> const& collisions,
+                 aod::McParticles const& particles,
+                 aod::McCollisions const&)
+  {
+    for (const auto& collision : collisions) {
+      if (!isCollisionSelected(collision))
+        continue; // MB selection
+      if (!collision.has_mcCollision())
+        continue;
+      const auto& mcCollision = collision.mcCollision();
+
+      for (const auto& particle : particles) {
+        if (particle.mcCollisionId() != mcCollision.globalIndex())
+          continue;
+        if (!particle.isPhysicalPrimary())
+          continue;
+        switch (particle.pdgCode()) {
+          case 321: // K+
+            registry.fill(HIST("K/GeneratedPositive"), particle.pt(), particle.eta(), particle.phi());
+            break;
+          case -321: // K-
+            registry.fill(HIST("K/GeneratedNegative"), particle.pt(), particle.eta(), particle.phi());
+            break;
+          case 310: // K0s
+            registry.fill(HIST("K0s/Generated"), particle.pt(), particle.eta(), particle.phi());
+            break;
+          default:
+            break;
+        }
+      }
+    }
+  }
+  PROCESS_SWITCH(SystematicsMapping, processMc, "Systematics study for K0s and charged Kaons on MC", false);
+};
+
+WorkflowSpec defineDataProcessing(ConfigContext const& cfgc) { return WorkflowSpec{adaptAnalysisTask<SystematicsMapping>(cfgc)}; }