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.
Particle physicists have been looking for so-called "sterile neutrinos" for a few decades now. They are a hypothesized particle that would have a tiny mass like the three known neutrinos but would not interact by the weak ...
Scientists working on the Short-Baseline Near Detector (SBND) at Fermi National Accelerator Laboratory have identified the detector's first neutrino interactions.
General Physics
Sep 10, 2024
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A central aim of the ATLAS Higgs physics program is to measure, with increasing precision, the strength of interactions of the Higgs boson with elementary fermions and bosons.
General Physics
Sep 9, 2024
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A team including researchers from the Laboratory for High Energy Physics at the University of Bern has successfully measured the interaction rates of neutrinos at unprecedented energies using the Large Hadron Collider (LHC) ...
General Physics
Jul 16, 2024
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Neutrinos have a quantum mechanical property called "flavor." This flavor can transform as neutrinos move through space. A major challenge is to keep track of both the physical movement of the neutrinos and their change of ...
General Physics
Jul 12, 2024
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The Belle II experiment is a large research effort aimed at precisely measuring weak-interaction parameters, studying exotic hadrons (i.e., a class of subatomic particles) and searching for new physical phenomena. This effort ...
Depictions of the Roman goddess of wisdom Minerva show her in flowing robes, wearing a noble war helmet and holding an owl. In contrast, the MINERvA experiment features a huge particle detector with the names of collaborating ...
General Physics
May 21, 2024
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The hydrogen atom was once considered the simplest atom in nature, composed of a structureless electron and a structured proton. However, as research progressed, scientists discovered a simpler type of atom, consisting of ...
Quantum Physics
May 10, 2024
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What is the mass of a neutrino at rest? This is one of the big unanswered questions in physics. Neutrinos play a central role in nature. A team led by Klaus Blaum, Director at the Max Planck Institute for Nuclear Physics ...
General Physics
Apr 19, 2024
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Last week, at the annual Rencontres de Moriond conference, the CMS collaboration presented a measurement of the effective leptonic electroweak mixing angle. The result is the most precise measurement performed at a hadron ...
General Physics
Apr 8, 2024
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