  The masses of the elementary particles as well as their charges and spins
belong to the fundamental physical constants. Presently, no fundamental theory
describing them is available, so their values remain mysterious. In this work
we offer an approach based on the Brown-York quasi-local energy which includes
the self-energy of an object. In order to compute this energy we model the
spacetime of the renormalized electron (and other leptons) by the Kerr-Newman
metric. Placing conditions on the associated energies at different radii we
arrive at various constraints on the mass, charge and spin which are derived
from the Planck scale. The large gap between the TeV-scale and the Planck
energy is due to the highly non-trivial behavior of the used quasi-local
potential.
