Fix reassignment of mother indices after pruning HF events in embedding

Author: fgrosa

MC/config/PWGHF/external/generator/generator_pythia8_embed_hf.C

@@ -280,7 +280,7 @@ Bool_t importParticles() override
 
         /// Establish if this particle comes from charm or beauty
         /// If not, ignore this particle and increase the number of discarded particles from the pp event
-        if(!isFromCharmOrBeauty(iPart, particlesHfEvent)) {
+        if(!(nEvsHF == 0 && iPart < 1) && !isFromCharmOrBeauty(iPart, particlesHfEvent)) {
             continue;
         }
         /// if we arrive here, then the current particle is from charm or beauty, keep it!
@@ -314,11 +314,13 @@ Bool_t importParticles() override
             idFirstMother = findKey(mapHfParticles, idFirstMother);
             /// If idFirstMother>=0, the 1st mother is from charm or beauty, i.e. is not a light-flavoured parton
             /// Instead, if idFirstMother==-1 from findKey this means that the first mother was a light-flavoured parton --> not stored in the map
-            if(idFirstMother >=0) {
+            if(idFirstMother >= 0) {
                 /// the 1st mother is from charm or beauty, i.e. is not a light-flavoured parton
                 if(idLastMother != idFirstMotherOrig) {
-                    if(idLastMother != -1) {
-                        /// idLastMother is >= 0
+                    idLastMother = findKey(mapHfParticles, idLastMother);
+                    if(idLastMother < 0) {
+                        // second mother not found, we set it to 0
+                        idLastMother = 0;
                     }
                 } else {
                     /// idLastMother is equal to idFirstMother
@@ -343,15 +345,17 @@ Bool_t importParticles() override
                 const int idMother = findKey(mapHfParticles, idMotherOrig);
                 if(idMother >= 0) {
                     /// this should mean that the mother is from HF, i.e. that we found the correct one
-                    idFirstMother = idMother;
-                    idLastMother = idFirstMother;
+                    if (idFirstMother < 0) {
+                        idFirstMother = idMother;
+                    }
+                    idLastMother = idMother;
                     foundAnyMother = true;
-                    break;
                 }
             }
-            // set last mother to -1 if no mother has been found so far
+            // set last mother to 0 if no mother has been found so far
             if (!foundAnyMother) {
-                idLastMother = -1;
+                idLastMother = 0;
+                idFirstMother = 0;
             }
         }
 
@@ -360,21 +364,21 @@ Bool_t importParticles() override
         idLastDaughter = findKey(mapHfParticles, idLastDaughter);
 
         /// adjust the particle mother and daughter indices
-        particle.SetFirstMother((idFirstMother >= 0) ? idFirstMother + offset : idFirstMother);
-        particle.SetLastMother((idLastMother >= 0) ? idLastMother + offset : idLastMother);
-	    particle.SetFirstDaughter((idFirstDaughter >= 0) ? idFirstDaughter + offset : idFirstDaughter);
-	    particle.SetLastDaughter((idLastDaughter >= 0) ? idLastDaughter + offset : idLastDaughter);
+        particle.SetFirstMother((idFirstMother > 0) ? idFirstMother + offset : idFirstMother);
+        particle.SetLastMother((idLastMother > 0) ? idLastMother + offset : idLastMother);
+	    particle.SetFirstDaughter((idFirstDaughter > 0) ? idFirstDaughter + offset : idFirstDaughter);
+	    particle.SetLastDaughter((idLastDaughter > 0) ? idLastDaughter + offset : idLastDaughter);
 
         /// copy inside this.mParticles from mGeneratorEvHF.mParticles, i.e. the particles generated in mGeneratorEvHF
         mParticles.push_back(particle);
 
       }
 
       // for debug
-      // LOG(info) << "-----------------------------------------------";
-      // LOG(info) << "============ After HF event " << nEvsHF;
-      // LOG(info) << "Full stack:";
-      // printParticleVector(mParticles);
+    //   LOG(info) << "-----------------------------------------------";
+    //   LOG(info) << "============ After HF event " << nEvsHF;
+    //   LOG(info) << "Full stack:";
+    //   printParticleVector(mParticles);
 
       /// one more event generated, let's update the counter and clear it, to allow the next generation
       nEvsHF++;