All three models predicted an increase of the electron mass if their velocities are approaching the speed of light.

Its typical value in GaAs systems is on the order of the electron mass in vacuum.

For positronium, the formula uses the reduced mass also, but in this case, it is exactly the electron mass divided by 2.

A neutrino has no electric charge and a mass that is one-millionth of the electron mass, perhaps even smaller.

Why is the electron mass such a tiny fraction of the Planck mass?

It has standard electron mass and other standard properties.

The electron mass is replaced with that of the proton.

This cross section is calculated neglecting the electron mass relative to the collision energy and including only the contribution from photon exchange.

They are similar to "Schrödinger" units but set the electron mass to unity and allow the gravitational constant to float.

However, poor performance was observed due the extremely high effective electron mass of Ge.