[PWGDQ] Add kDeltaEtaPair2 (#8328)

Author: Shunsuke-Kurita

PWGDQ/Core/HistogramsLibrary.cxx

@@ -1161,6 +1161,8 @@ void o2::aod::dqhistograms::DefineHistograms(HistogramManager* hm, const char* h
     }
     if (subGroupStr.Contains("correlation-emu")) {
       hm->AddHistogram(histClass, "DeltaPhiPair2", "", false, 600, -0.5 * TMath::Pi(), 1.5 * TMath::Pi(), VarManager::kDeltaPhiPair2);
+      hm->AddHistogram(histClass, "DeltaEtaPair2", "", false, 600, -1.0, 5.0, VarManager::kDeltaEtaPair2);
+      hm->AddHistogram(histClass, "DeltaPhiPair2_DeltaEtaPair2", "", false, 600, -0.5 * TMath::Pi(), 1.5 * TMath::Pi(), VarManager::kDeltaPhiPair2, 600, -1.0, 5.0, VarManager::kDeltaEtaPair2);
     }
     if (subGroupStr.Contains("dielectrons")) {
       if (subGroupStr.Contains("prefilter")) {

PWGDQ/Core/VarManager.cxx

@@ -879,6 +879,8 @@ void VarManager::SetDefaultVarNames()
   fgVariableUnits[kPhiCS] = "rad.";
   fgVariableNames[kDeltaPhiPair2] = "#Delta#phi";
   fgVariableUnits[kDeltaPhiPair2] = "rad.";
+  fgVariableNames[kDeltaEtaPair2] = "#Delta#eta";
+  fgVariableUnits[kDeltaEtaPair2] = "";
   fgVariableNames[kPsiPair] = "#Psi_{pair}";
   fgVariableUnits[kPsiPair] = "rad.";
   fgVariableNames[kDeltaPhiPair] = "#Delta#phi";

PWGDQ/Core/VarManager.h

@@ -593,6 +593,7 @@ class VarManager : public TObject
     kPhiHE,
     kPhiCS,
     kDeltaPhiPair2,
+    kDeltaEtaPair2,
     kPsiPair,
     kDeltaPhiPair,
     kOpeningAngle,
@@ -2558,6 +2559,10 @@ void VarManager::FillPair(T1 const& t1, T2 const& t2, float* values)
     }
   }
 
+  if (fgUsedVars[kDeltaEtaPair2]) {
+    values[kDeltaEtaPair2] = v1.Eta() - v2.Eta();
+  }
+
   if (fgUsedVars[kPsiPair]) {
     values[kDeltaPhiPair] = (t1.sign() * fgMagField > 0.) ? (v1.Phi() - v2.Phi()) : (v2.Phi() - v1.Phi());
     double xipair = TMath::ACos((v1.Px() * v2.Px() + v1.Py() * v2.Py() + v1.Pz() * v2.Pz()) / v1.P() / v2.P());
@@ -2907,6 +2912,10 @@ void VarManager::FillPairME(T1 const& t1, T2 const& t2, float* values)
     }
   }
 
+  if (fgUsedVars[kDeltaEtaPair2]) {
+    values[kDeltaEtaPair2] = v1.Eta() - v2.Eta();
+  }
+
   // TODO: provide different computations for vn
   // Compute the scalar product UQ for two muon from different event using Q-vector from A, for second and third harmonic
   values[kU2Q2Ev1] = values[kQ2X0A1] * std::cos(2 * v1.Phi()) + values[kQ2Y0A1] * std::sin(2 * v1.Phi());