Add a utility function to return a leading track of the Reconstructed…

…Particle

src/cpp/include/UTIL/ReconstructedParticleTools.h

@@ -0,0 +1,22 @@
+#ifndef UTIL_ReconstructedParticleTools_H
+#define UTIL_ReconstructedParticleTools_H 1
+
+#include "EVENT/ReconstructedParticle.h"
+#include "EVENT/Track.h"
+#include "TrackTools.h"
+
+namespace UTIL{
+    /** Extract the leading track in case of multiple tracks attached to a single ReconstructedParticle.
+    * @author Bohdan Dudar
+    * @version August 2022
+    */
+    EVENT::Track* getLeadingTrack(const EVENT::ReconstructedParticle* particle, double bz){
+        const TrackVec& tracks = particle->getTracks();
+        if ( tracks.empty() ) return nullptr;
+        auto sortByMomentum = [&bz, &getTrackMomentum](const EVENT::Track* a, const EVENT::Track* b) { return getTrackMomentum(a, bz) < getTrackMomentum(b, bz) };
+        EVENT::Track* leadingTrack = *std::max_element(tracks.begin(), tracks.end(), sortByMomentum);
+
+        return leadingTrack;
+    }
+
+#endif