From 5f74fca2ce169762de1746184c0c18c98b4643a0 Mon Sep 17 00:00:00 2001
From: Fabrizio Grosa <fabrizio.grosa@cern.ch>
Date: Tue, 5 Aug 2025 17:39:28 +0200
Subject: [PATCH] Fix DeltaPhi definition

---
 PWGDQ/Tasks/taskJpsiHf.cxx | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/PWGDQ/Tasks/taskJpsiHf.cxx b/PWGDQ/Tasks/taskJpsiHf.cxx
index 79d9348940a..ef415259a02 100644
--- a/PWGDQ/Tasks/taskJpsiHf.cxx
+++ b/PWGDQ/Tasks/taskJpsiHf.cxx
@@ -97,15 +97,16 @@ struct taskJPsiHf {
     float deltaRap = -999;
     float deltaPhi = -999;
 
-    for (auto& dilepton : dileptons) {
+    for (auto const& dilepton : dileptons) {
       ptDilepton = RecoDecay::pt(dilepton.px(), dilepton.py());
       rapDilepton = RecoDecay::y(std::array{dilepton.px(), dilepton.py(), dilepton.pz()}, constants::physics::MassJPsi);
       phiDilepton = RecoDecay::phi(dilepton.px(), dilepton.py());
 
-      for (auto& dmeson : dmesons) {
+      for (auto const& dmeson : dmesons) {
         ptDmeson = RecoDecay::pt(dmeson.px(), dmeson.py());
         phiDmeson = RecoDecay::phi(dmeson.px(), dmeson.py());
-        deltaPhi = RecoDecay::constrainAngle(phiDilepton - phiDmeson, -o2::constants::math::PIHalf);
+        float absDeltaPhiRaw = std::abs(phiDilepton - phiDmeson);
+        deltaPhi = (absDeltaPhiRaw < o2::constants::math::PI) ? absDeltaPhiRaw : o2::constants::math::TwoPI - absDeltaPhiRaw;
 
         auto ptBinDmesForBdt = findBin(binsPtDmesForBdt, ptDmeson);
         if (ptBinDmesForBdt == -1) {