The undemocratic proton
Article Abstract:
The proton is the lightest stable composite object in the Universe, but it has a complex structure. The HERMES collaboration at the HERA accelerator in Hamburg, have identified the contribution of individual quarks to the momentum of the proton, using semi-inclusive deep-inelastic scattering of a positron beam. Both the HERMES group and the NuSea collaboration at the Fermilab Tevatron have observed an excess of virtual down-antiquarks over up-antiquarks, which is contrary to predictions that the two types of antiquark should be present within the proton in equal numbers.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1999
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Beauty stays as charm wilts
Article Abstract:
Experiments on high energy physics refute the theory of supersymmetry and provide comprehensive support to the Standard Model of quarks and leptons interacting via the electroweak and quantum-chromodynamic (QCD) forces. This model explains the experiments satisfactorily but suffers from a certain degree of arbitrariness, and totally ignores gravitational effects. The incorporation of the mass of the Higgs boson updates the electroweak theory but the properties of the neutrinos are still a stumbling block to a complete characterization of QCD forces.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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Casting more light on light
Article Abstract:
Physicists at the 9th International Workshop on Photon-Photon Collisions in San Diego, CA, from Mar 22-26, 1992, reviewed the latest attempts at testing the classical theory of electromagnetic waves, or photons, against the quantum theory of electrodynamics (QED). Classical theory holds that photons cannot interact, whereas QED maintains that can interact if made up two virtual charged particles. Scientists managing Cornell University's lower-energy collider reported evidence confirming the quantum chromodynamic theory of particle physics.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1992
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