The ultimate constituents of matter

Design of these toroidal magnets and of the mechanical structure of Atlas is but one contribution by Dapnia to this detector, here being mounted at Cern.

Basic research in the subnuclear realm deals with tiniest entities in our Universe. Dapnia strives to answer unsolved questions about these: What is the origin of mass? Is there a single, universal force? What are the properties of neutrinos?


Maj : 07/02/2005 (528)


In the Big Bang theory, matter and antimatter appeared in equal proportions at the very beginning of the Universe. Particles and antiparticles mutually annihilated each other, but one billionth of the baryons subsisted to form the matter of the world around us. The origin of this extraordinarily slight excess matter remains one of the major enigmas of particle physics and cosmology. One of the possible explanations is based on the 'CP violation' phenomenon, which is actively investigated through experiments ... Lire la suite »
SPhN is strongly engaged in the study of the partonic structure - in terms of quarks and gluons - of nucleons, protons and neutrons. Nucleons are singular objects as 90% of their mass originates not from their constituent masses, but rather the strong interaction they experience. Nucleons are also a benchmark laboratory to study confinement mechanisms which remain an open key point, although QCD is a well established theroy in the standard model. The study of the nucleon structure in terms of quarks and gluons is thus ... Lire la suite »
Neutrinos are quite remarkable elementary particles which are produced in great abundance in the sun, in the atmosphere and at the core of nuclear power reactors. DAPNIA has been interested in them for a very long time. It has now been established that although they are very light, neutrinos do not have zero mass. It remains to be determined how these masses are distributed among the three known varieties of neutrino: ne, nμ and nτ Based on recent progress in experiments, it seems that these ... Lire la suite »
The Standard Model of elementary particles provides an incredibly precise description of matter and its interactions up to the highest energy explored so far. And yet, one of its predictions remains to be verified: the electroweak symmetry-breaking mechanism, which points to the existence of a new particle called the "Higgs boson". Furthermore, several extensions of the Standard Model, such as supersymmetric models, predict the existence of new particles. These theories will be extensively tested by the Atlas ... Lire la suite »
Experiments using accelerators at the highest accessible energy can be used to perform precise tests on the Standard Model. At CERN, the LEP has obtained many results leading to more precise knowledge in this field. The degree of precision attained in measuring the mass of the W boson has been exploited to obtain an indirect upper bound for the mass of the Higgs boson through quantum corrections. The Tevatron accelerator at Fermilab (near Chicago) has yielded results on the physics and mass of the top quark. The HERA ... Lire la suite »
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