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.
The NA62 Collaboration has dramatically reduced the uncertainty in its measurement of an extremely rare particle decay, in results just presented at the 2026 La Thuile conference.
General Physics
Mar 4, 2026
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26
Muons are unstable subatomic particles that spontaneously and rapidly transform into other particles via a process known as electroweak decay. Altering the speed with which muons decay into other particles was so far deemed ...
Scientists are a step closer to solving one of the universe's biggest mysteries as new research finds evidence that two of its least understood components may be interacting, offering a rare window into the darkest recesses ...
Astronomy
Jan 7, 2026
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236
Experimental particle physicists working at the MicroBooNE experiment at Fermilab National Accelerator Laboratory have found evidence against the existence of a "sterile" type of neutrino hypothesized to be responsible for ...
Astronomy
Jan 1, 2026
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232
Although its existence had been theorized for decades, the Higgs boson was finally observed to exist in 2012 at the Large Hadron Collider (LHC) at CERN. Since then, it has continued to be heavily studied at the LHC. Now, ...
Neutrinos, though nearly invisible, are among the most numerous matter particles in the universe. The Standard Model recognizes three types, but the discovery of neutrino oscillations revealed they have mass and can change ...
General Physics
Dec 3, 2025
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64
For experimental physicists, the latest measurement of the muon is the best of times. For theorists there's still work to do.
In a Physical Review Letters study, the HOLMES collaboration has achieved the most stringent upper bound on the effective electron neutrino mass ever obtained using a calorimetric approach, setting a limit of less than 27 ...
Neutrinos are very common fundamental particles included in the Standard Model of particle physics. Measuring their properties allows for creating more accurate models of the birth of the universe, the life of stars and the ...
General Physics
Oct 7, 2025
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69
A recent Physical Review Letters publication presents a thorough analysis of MicroBooNE detector data, investigating the anomalous surplus of neutrino-like events detected by the preceding MiniBooNE experiment.
