PWGHF: add abs value in selections, use registry, add inv mass cut ToXiPi tasks

PWGHF/TableProducer/candidateCreatorToXiPi.cxx

@@ -73,6 +73,11 @@ struct HfCandidateCreatorToXiPi {
   Configurable<std::string> ccdbPathGrp{"ccdbPathGrp", "GLO/GRP/GRP", "Path of the grp file (Run 2)"};
   Configurable<std::string> ccdbPathGrpMag{"ccdbPathGrpMag", "GLO/Config/GRPMagField", "CCDB path of the GRPMagField object (Run 3)"};
 
+  // cascade invariant mass cuts
+  Configurable<bool> doCascadeInvMassCut{"doCascadeInvMassCut", false, "Use invariant mass cut to select cascade candidates"};
+  Configurable<double> sigmaInvMassCascade{"sigmaInvMassCascade", 0.0025, "Invariant mass cut for cascade (sigma)"};
+  Configurable<int> nSigmaInvMassCut{"nSigmaInvMassCut", 4, "Number of sigma for invariant mass cut"};
+
   Service<o2::ccdb::BasicCCDBManager> ccdb;
   o2::base::MatLayerCylSet* lut;
   o2::base::Propagator::MatCorrType matCorr = o2::base::Propagator::MatCorrType::USEMatCorrLUT;
@@ -169,6 +174,13 @@ struct HfCandidateCreatorToXiPi {
           }
         }
 
+        // use invariant mass cut to select cascades candidates
+        if (doCascadeInvMassCut) {
+          if (std::abs(casc.mXi() - massXiFromPDG) > (nSigmaInvMassCut * sigmaInvMassCascade)) {
+            continue;
+          }
+        }
+
         //--------------------------reconstruct V0 track---------------------------
         // pseudorapidity
         double pseudorapV0PosDau = trackV0Dau0.eta();