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The theory is commonly viewed as describing the fundamental set of particles – the leptons, quarks, gauge bosons and the Higgs boson. The Standard Model is renormalizable and mathematically self-consistent; [ 1 ] however, despite having huge and continued successes in providing experimental predictions, it does leave some unexplained ...
In particle physics, a lepton is an elementary particle of half-integer spin (spin 1 / 2 ) that does not undergo strong interactions. [1] Two main classes of leptons exist: charged leptons (also known as the electron-like leptons or muons), including the electron, muon, and tauon, and neutral leptons, better known as neutrinos.
They are the fundamental objects of quantum field theory. Many families and sub-families of elementary particles exist. Elementary particles are classified according to their spin. Fermions have half-integer spin while bosons have integer spin. All the particles of the Standard Model have been experimentally observed, including the Higgs boson ...
When originally defined in the 1950s, the terms baryons, mesons and leptons referred to masses; however, after the quark model became accepted in the 1970s, it was recognised that baryons are composites of three quarks, mesons are composites of one quark and one antiquark, while leptons are elementary and are defined as the elementary fermions ...
Penguin diagram: a quark changes flavor via a W or Z loop Tadpole diagram: One loop diagram with one external leg Self-interaction or oyster diagram An electron emits and reabsorbs a photon Box diagram The box diagram for kaon oscillations: Photon-photon scattering: Higgs boson production: Via gluons and top quarks: Via quarks and W or Z bosons ...
The theory of the strong interaction (i.e. quantum chromodynamics, QCD), to which many contributed, acquired its modern form in 1973–74 when asymptotic freedom was proposed [23] [24] (a development that made QCD the main focus of theoretical research) [25] and experiments confirmed that the hadrons were composed of fractionally charged quarks.
From these conclusions about plants and animals, two of the three tenets of cell theory were postulated. 1. All living organisms are composed of one or more cells 2. The cell is the most basic unit of life. Schleiden's theory of free cell formation through crystallization was refuted in the 1850s by Robert Remak, Rudolf Virchow, and Albert ...
All leptons carry a lepton number L = 1. In addition, leptons carry weak isospin, T 3, which is − 1 / 2 for the three charged leptons (i.e. electron, muon and tau) and + 1 / 2 for the three associated neutrinos. Each doublet of a charged lepton and a neutrino consisting of opposite T 3 are said to constitute one generation of ...