Brief Introduction of Lepton

In particle physics, a lepton is an elementary particle of half-integer “1/2” spin that does not undergo strong interactions.

Two main classes of leptons exist, charged leptons, and neutral leptons.

charged	electron	muon	tau
neutral	electron neutrino	muon neutrino	tau neutrino

Charged leptons can combine with other particles to form various composite particles such as atoms and positronium, while neutrinos rarely interact with anything, and are consequently rarely observed.

The first neutrino, the electron neutrino, was proposed by Wolfgang Pauli in 1930 to explain certain characteristics of beta decay.

Leptons own various intrinsic properties, including electric charge, spin, and mass.

The first charged lepton, the electron, was theorized in the mid-19th century by a lot scientists and was discovered in 1897 by J. J. Thomson.

The best familiar of all leptons is the electron.

Electrons own the least mass of all the charged leptons.

Particle name	Symbol	Charge Q (e)	Spin J	Mass (MeV/c²)	Lifetime (seconds)
Electron	− e	−1	1⁄2	0.510998910 (±13)	Stable
Muon	− μ	−1	1⁄2	105.6583668 (±38)	2.197019×10⁻⁶ (±21)
Tau	− τ	−1	1⁄2	1776.84 (±.17)	2.906×10⁻¹³ (±.010)
Electron neutrino	ν_e	0	1⁄2	<0.0000022	Unknown
Muon neutrino	ν_μ	0	1⁄2	< 0.17	Unknown
Tau neutrino	ν_τ	0	1⁄2	< 15.5	Unknown