Leptons are elementary fermionic particles constituting a fundamental physical system in the Standard Model, characterized by half-integer spin (spin-½), lack of color charge, and participation in electroweak but not strong interactions. They occur in three generations, each comprising a charged lepton (electron, muon, tau) and its associated neutrino, distinguished by lepton flavor quantum numbers. Leptons obey Fermi–Dirac statistics and are subject to conservation laws such as total lepton number and, to high precision, individual flavor numbers in most processes. Their dynamics are described by the electroweak sector’s SU(2)\(_L\)×U(1)\(_Y\) gauge symmetry, with mass eigenstates arising from Yukawa couplings and, for neutrinos, flavor mixing via the PMNS matrix.
In a talk at the ongoing Rencontres de Moriond conference, the ATLAS collaboration presented the result of its latest test of a key principle of the Standard Model of particle physics known as lepton flavor universality. ...
General Physics
Mar 26, 2024
0
163
In March 2024, the CMS collaboration announced the observation of two photons creating two tau leptons in proton–proton collisions. It is the first time that this process has been seen in proton–proton collisions, which was ...
General Physics
Mar 26, 2024
0
427
The discovery that neutrinos have mass was groundbreaking. However, their absolute mass remains unknown. Neutrinoless double beta decay experiments aim to determine whether neutrinos are their own antiparticles and, if so, ...
General Physics
Jan 22, 2024
0
1610
A group of physicists, three with Harvard University's Department of Physics and Laboratory for Particle Physics and Cosmology, and the fourth with the University of Liverpool, has found evidence suggesting that additional ...
