EventFiltering/PWGHF: fix sign of pion bachelor in B+ -> D0bar pi+ (#8187)

Co-authored-by: ALICE Action Bot <alibuild@cern.ch>

Author: fgrosa

EventFiltering/PWGHF/HFFilter.cxx

@@ -428,7 +428,7 @@ struct HfFilter { // Main struct for HF triggers
 
           if (!keepEvent[kBeauty3P] && isBeautyTagged) {
             auto isTrackSelected = helper.isSelectedTrackForSoftPionOrBeauty(track, trackParThird, dcaThird, kBeauty3P);
-            if (isTrackSelected && ((TESTBIT(selD0, 0) && track.sign() > 0) || (TESTBIT(selD0, 1) && track.sign() < 0))) {
+            if (TESTBIT(isTrackSelected, kForBeauty) && ((TESTBIT(selD0, 0) && track.sign() < 0) || (TESTBIT(selD0, 1) && track.sign() > 0))) { // D0 pi- and D0bar pi+
               auto massCand = RecoDecay::m(std::array{pVec2Prong, pVecThird}, std::array{massD0, massPi});
               auto pVecBeauty3Prong = RecoDecay::pVec(pVec2Prong, pVecThird);
               auto ptCand = RecoDecay::pt(pVecBeauty3Prong);
@@ -441,47 +441,49 @@ struct HfFilter { // Main struct for HF triggers
                 if (activateQA) {
                   hMassVsPtB[kBplus]->Fill(ptCand, massCand);
                 }
-              } else if (TESTBIT(isTrackSelected, kSoftPionForBeauty)) {
-                std::array<float, 2> massDausD0{massPi, massKa};
-                auto massD0dau = massD0Cand;
-                if (track.sign() < 0) {
-                  massDausD0[0] = massKa;
-                  massDausD0[1] = massPi;
-                  massD0dau = massD0BarCand;
+              }
+            } else if (TESTBIT(isTrackSelected, kSoftPionForBeauty) && ((TESTBIT(selD0, 0) && track.sign() > 0) || (TESTBIT(selD0, 1) && track.sign() < 0))) { // D0 pi+ and D0bar pi-
+              auto pVecBeauty3Prong = RecoDecay::pVec(pVec2Prong, pVecThird);
+              auto ptCand = RecoDecay::pt(pVecBeauty3Prong);
+              std::array<float, 2> massDausD0{massPi, massKa};
+              auto massD0dau = massD0Cand;
+              if (track.sign() < 0) {
+                massDausD0[0] = massKa;
+                massDausD0[1] = massPi;
+                massD0dau = massD0BarCand;
+              }
+              auto massDstarCand = RecoDecay::m(std::array{pVecPos, pVecNeg, pVecThird}, std::array{massDausD0[0], massDausD0[1], massPi});
+              auto massDiffDstar = massDstarCand - massD0dau;
+              if (cutsPtDeltaMassCharmReso->get(0u, 0u) <= massDiffDstar && massDiffDstar <= cutsPtDeltaMassCharmReso->get(1u, 0u) && ptCand > cutsPtDeltaMassCharmReso->get(2u, 0u)) { // additional check for B0->D*pi polarization studies
+                if (activateQA) {
+                  hMassVsPtC[kNCharmParticles]->Fill(ptCand, massDiffDstar);
                 }
-                auto massDstarCand = RecoDecay::m(std::array{pVecPos, pVecNeg, pVecThird}, std::array{massDausD0[0], massDausD0[1], massPi});
-                auto massDiffDstar = massDstarCand - massD0dau;
-                if (cutsPtDeltaMassCharmReso->get(0u, 0u) <= massDiffDstar && massDiffDstar <= cutsPtDeltaMassCharmReso->get(1u, 0u) && ptCand > cutsPtDeltaMassCharmReso->get(2u, 0u)) { // additional check for B0->D*pi polarization studies
-                  if (activateQA) {
-                    hMassVsPtC[kNCharmParticles]->Fill(ptCand, massDiffDstar);
+                for (const auto& trackIdB : trackIdsThisCollision) { // start loop over tracks
+                  auto trackB = trackIdB.track_as<BigTracksPID>();
+                  if (track.globalIndex() == trackB.globalIndex()) {
+                    continue;
+                  }
+                  auto trackParFourth = getTrackPar(trackB);
+                  o2::gpu::gpustd::array<float, 2> dcaFourth{trackB.dcaXY(), trackB.dcaZ()};
+                  std::array<float, 3> pVecFourth = trackB.pVector();
+                  if (trackB.collisionId() != thisCollId) {
+                    o2::base::Propagator::Instance()->propagateToDCABxByBz({collision.posX(), collision.posY(), collision.posZ()}, trackParFourth, 2.f, noMatCorr, &dcaFourth);
+                    getPxPyPz(trackParFourth, pVecFourth);
                   }
-                  for (const auto& trackIdB : trackIdsThisCollision) { // start loop over tracks
-                    auto trackB = trackIdB.track_as<BigTracksPID>();
-                    if (track.globalIndex() == trackB.globalIndex()) {
-                      continue;
-                    }
-                    auto trackParFourth = getTrackPar(trackB);
-                    o2::gpu::gpustd::array<float, 2> dcaFourth{trackB.dcaXY(), trackB.dcaZ()};
-                    std::array<float, 3> pVecFourth = trackB.pVector();
-                    if (trackB.collisionId() != thisCollId) {
-                      o2::base::Propagator::Instance()->propagateToDCABxByBz({collision.posX(), collision.posY(), collision.posZ()}, trackParFourth, 2.f, noMatCorr, &dcaFourth);
-                      getPxPyPz(trackParFourth, pVecFourth);
-                    }
 
-                    auto isTrackFourthSelected = helper.isSelectedTrackForSoftPionOrBeauty(trackB, trackParFourth, dcaFourth, kBeauty3P);
-                    if (track.sign() * trackB.sign() < 0 && TESTBIT(isTrackFourthSelected, kForBeauty)) {
-                      auto massCandB0 = RecoDecay::m(std::array{pVecBeauty3Prong, pVecFourth}, std::array{massDStar, massPi});
-                      if (std::fabs(massCandB0 - massB0) <= deltaMassBeauty->get(0u, 2u)) {
-                        keepEvent[kBeauty3P] = true;
-                        // fill optimisation tree for D0
-                        if (applyOptimisation) {
-                          optimisationTreeBeauty(thisCollId, 413, pt2Prong, scores[0], scores[1], scores[2], dcaFourth[0]); // pdgCode of D*(2010)+: 413
-                        }
-                        if (activateQA) {
-                          auto pVecBeauty4Prong = RecoDecay::pVec(pVec2Prong, pVecThird, pVecFourth);
-                          auto ptCandBeauty4Prong = RecoDecay::pt(pVecBeauty4Prong);
-                          hMassVsPtB[kB0toDStar]->Fill(ptCandBeauty4Prong, massCandB0);
-                        }
+                  auto isTrackFourthSelected = helper.isSelectedTrackForSoftPionOrBeauty(trackB, trackParFourth, dcaFourth, kBeauty3P);
+                  if (track.sign() * trackB.sign() < 0 && TESTBIT(isTrackFourthSelected, kForBeauty)) {
+                    auto massCandB0 = RecoDecay::m(std::array{pVecBeauty3Prong, pVecFourth}, std::array{massDStar, massPi});
+                    if (std::fabs(massCandB0 - massB0) <= deltaMassBeauty->get(0u, 2u)) {
+                      keepEvent[kBeauty3P] = true;
+                      // fill optimisation tree for D0
+                      if (applyOptimisation) {
+                        optimisationTreeBeauty(thisCollId, 413, pt2Prong, scores[0], scores[1], scores[2], dcaFourth[0]); // pdgCode of D*(2010)+: 413
+                      }
+                      if (activateQA) {
+                        auto pVecBeauty4Prong = RecoDecay::pVec(pVec2Prong, pVecThird, pVecFourth);
+                        auto ptCandBeauty4Prong = RecoDecay::pt(pVecBeauty4Prong);
+                        hMassVsPtB[kB0toDStar]->Fill(ptCandBeauty4Prong, massCandB0);
                       }
                     }
                   }