Nothing is more emblematic of an electron than its negative charge. It's the trait that determines how the particle behaves in electromagnetic environments, such as a wire's electric field and Earth's magnetic field.
Yet physicists have long known that electrons also respond to a nuclear force, called the weak force, that's responsible for radioactive decay. Now, researchers have directly measured that weak force between pairs of electrons. In so doing, they've determined another kind of charge on the electron, its weak charge.
The fact that electrons, which aren't nuclear particles, respond to a nuclear force at all stems from a deep connection between the electromagnetic and weak forces (SN: 10/16/99, p. 247).
The new results come from experiments at the Stanford (Calif.) Linear Accelerator Center (SLAC). They show that the weak force between electrons is less than a millionth the strength of the electromagnetic force, says Krishna S. Kumar of the University of