1. Nmgtr ------ Number of GTracks with pT>1.5 GeV for each event
2. mgtrpt ------ Transverse momentum Pt of GTR tracks
3. mgtrpx ------ Px of GTR tracks
4. mgtrpy ------ Py of GTR tracks
5. mgtrpz ------ Pz of GTR tracks
6. mgtrE ------ Energy of GTR tracks
7. mgtrphi ------ Phi for GTR tracks
8. mgtreta ------ Eta for GTR tracks
9. mgtrmass ------ Invariant mass of two
highest Pt tracks (if Nmgtr>1)