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Related to leptons: Baryons, Bosons, Hadrons


(lep -tonz) A class of pointlike elementary particles that do not participate in strong interactions (see fundamental forces); it includes the electron, muon, the massive tau lepton, the neutrinos, and their associated antiparticles. Leptons show no evidence of any internal structure. See also Big Bang theory.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a class of elementary particles that do not have strong interaction—that is, they participate only in electromagnetic, weak, and gravitational interactions. The electron, muon, and electron and muon neutrinos and their corresponding antiparticles are classified as leptons. All leptons have a spin of ½ (that is, they are fermions). The name “lepton” (from Greek leptos, “small,” “light”) is associated with the fact that their mass is less than that of any other particle except the photon.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The above predictions are obtained on the basis of the special combinations of texture zeros and other special properties of leptons mass matrices.
In this paper, we propose a special combination of texture zeros of leptons mass matrices with an economical and stable structure.
Figure 1 is a schematic diagram that shows formations of four generations of leptons from annihilations of up and down quarks and antiquarks with one excited quantum state for each of them.
The first generation of leptons is formed by annihilations between the ground state up, ground state antiup, ground state down, and ground state antidown quarks (see the red arrow lines of Figure 1).
However, being the most massive and shortest-lived lepton, the tau lepton travels only about a millimeter before breaking apart.
In each of four cases, or events, one track caroms off at a new angle after about a millimeter--the giveaway that a tau lepton from the tau neutrino-nucleus impact decayed into another charged particle plus neutral companions.
For example, so-called supersymmetric theories, which permit the unification of the strong and electroweak forces, posit the existence of partners for each of the matter-making fermions (leptons and quarks) and force-carrying bosons of the standard model.
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