Lorentz invariance and the spinor-helicity formalism yield the U(1) and SU(3) fermion symmetry Eckart Marsch and Yasuhito Narita Eur. Phys. J. Plus, 137 7 (2022) 818 Published online: 15 July 2022 DOI: 10.1140/epjp/s13360-022-03001-1