Quarks, the particles from which atomic nuclei are made, were reckoned to have such fractional charges, but since it is impossible to isolate a quark, its charge cannot be measured directly.
Values for such basic properties as the fractional charges of quarks or the masses of quarks and leptons must be inserted "by hand" into the model that is, they are determined by experiment and observation rather than by theoretical predictions.
The experiments also showed that the partons can indeed have fractional charges of +2/3e or −1/3e and thus confirmed one of the more surprising predictions of the quark model.
For example, quarks must have charges of +2/3e or −1/3e, which should be very easy to spot in certain kinds of detectors; but intensive searches, both in cosmic rays and using particle accelerators, have never revealed any convincing evidence for fractional charge of this kind.
There is a real question here as to whether or not fractional charges exist in nature.
Quasi-particles made up of an electron bound to two vortices would give rise to fractional charges of one-third; and at slightly lower magnetic fields, even smaller fractional charges could appear.
The back side of the slab was saturated with hydrogen atoms of fractional charge.
He uses Morpurgo's search for free quarks, or fractional charges of \ \tfrac{1}{3} e\) or \ \tfrac{2}{3} e\), where \ e\) is the charge of the electron.
In 1983 Robert Laughlin, now at Stanford University, proposed an explanation for the FQH effect, and although the theory was widely accepted, it included a strange concept: fractional charges.
It was only when Morpurgo's apparatus could reproduce known measurements that it could be trusted and used to search for fractional charge.
