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Louis Michel (physicist)
Louis Michel (1923–1999) was a French mathematical physicist at the Institut des Hautes Études Scientifiques (IHÉS). He was born in Roanne, in the Loire (department), Loire Departments of France, department in central France, on 4 May 1923, and died in Bures-sur-Yvette (Essonne), in the Île-de-France (region), Île-de-France region, on 30 December 1999. Biography Michel completed his studies at the École Polytechnique in Paris. After World War II, he went to Manchester, England, where he worked on weak interactions. Back in France, he was teaching in Lille and Orsay before creating the ''Centre de Physique Théorique of the École polytechnique (France), École Polytechnique'' (CPHT) in Palaiseau. In 1962, he became a permanent professor at ''Institut des Hautes Études Scientifiques'' (IHÉS) in Bures-sur-Yvette, where he remained until his retirement, and as an emeritus professor until his death. Louis Michel was President of the Société Française de Physique between 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Institut Des Hautes Études Scientifiques
The Institut des hautes études scientifiques (IHÉS; English: Institute of Advanced Scientific Studies) is a French research institute supporting advanced research in mathematics and theoretical physics. It is located in Bures-sur-Yvette, just south of Paris. It is an independent research institute in a partnership with the University of Paris-Saclay. History The IHÉS was founded in 1958 by businessman and mathematical physicist Léon Motchane with the help of Robert Oppenheimer and Jean Dieudonné as a research centre in France, modeled on the renowned Institute for Advanced Study in Princeton, United States. The strong personality of Alexander Grothendieck and the broad sweep of his revolutionizing theories were a dominating feature of the first ten years at the IHÉS. René Thom received an invitation from IHÉS in 1963 and after his appointment remained there until his death in 2002. Dennis Sullivan is remembered as one who had a special talent for encouraging fruitf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
École Polytechnique (France)
École polytechnique, also known as Polytechnique or l'X , is a ''grande école'' university located in Palaiseau, France. It specializes in science and engineering and is a founding member of the Polytechnic Institute of Paris. The school was founded in 1794 by mathematician Gaspard Monge during the French Revolution and was militarized under Napoleon I in 1804. It is still supervised by the French Ministry of Armed Forces. Originally located in the Latin Quarter in central Paris, the institution moved to Palaiseau in 1976, in the Paris-Saclay technology cluster. Polytechnique’s historic engineering graduate program has a highly selective admission process consisting of written and oral examinations, following ''classes préparatoires'' or a bachelor’s degree. French engineering students undergo initial military training and have the status of paid officer cadets. The school has also been awarding doctorates since 1985, masters since 2005 and bachelors since 2017. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spin (physics)
Spin is a conserved quantity carried by elementary particles, and thus by composite particles (hadrons) and atomic nucleus, atomic nuclei. Spin is one of two types of angular momentum in quantum mechanics, the other being ''orbital angular momentum''. The orbital angular momentum operator is the quantum-mechanical counterpart to the classical angular momentum of orbital revolution and appears when there is periodic structure to its wavefunction as the angle varies. For photons, spin is the quantum-mechanical counterpart of the Polarization (waves), polarization of light; for electrons, the spin has no classical counterpart. The existence of electron spin angular momentum is inferred from experiments, such as the Stern–Gerlach experiment, in which silver atoms were observed to possess two possible discrete angular momenta despite having no orbital angular momentum. The existence of the electron spin can also be inferred theoretically from the spin–statistics theorem and from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bargmann–Michel–Telegdi Equation
In physics, Larmor precession (named after Joseph Larmor) is the precession of the magnetic moment of an object about an external magnetic field. The phenomenon is conceptually similar to the precession of a tilted classical gyroscope in an external torque-exerting gravitational field. Objects with a magnetic moment also have angular momentum and effective internal electric current proportional to their angular momentum; these include electrons, protons, other fermions, many atomic and nuclear systems, as well as classical macroscopic systems. The external magnetic field exerts a torque on the magnetic moment, :\vec = \vec\times\vec = \gamma\vec\times\vec, where \vec is the torque, \vec is the magnetic dipole moment, \vec is the angular momentum vector, \vec is the external magnetic field, \times symbolizes the cross product, and \gamma is the gyromagnetic ratio which gives the proportionality constant between the magnetic moment and the angular momentum. The angular mome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Michel Parameters
The Michel parameters, usually denoted by \rho, \eta, \xi and \delta, are four parameters used in describing the phase space distribution of leptonic decays of charged leptons, l_^-\rightarrow l_^\nu_\bar. They are named after the physicist Louis Michel. Sometimes instead of \delta, the product \xi\delta is quoted. Within the Standard Model of electroweak interactions, these parameters are expected to be : \rho=, \quad \eta=0, \quad \xi=1, \quad \xi\delta=. Precise measurements of energy and angular distributions of the daughter leptons in decays of polarized muons and tau leptons are so far in good agreement with these predictions of the Standard Model. Muon decay Consider the decay of the positive muon: :\mu^+\to e^+ + \nu_e + \bar\nu_\mu. In the muon rest frame, energy and angular distributions of the positrons emitted in the decay of a polarised muon expressed in terms of Michel parameters are the following, neglecting electron and neutrino masses and the radiative corrections ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spontaneous Symmetry Breaking
Spontaneous symmetry breaking is a spontaneous process of symmetry breaking, by which a physical system in a symmetric state spontaneously ends up in an asymmetric state. In particular, it can describe systems where the equations of motion or the Lagrangian obey symmetries, but the lowest-energy vacuum solutions do not exhibit that same symmetry. When the system goes to one of those vacuum solutions, the symmetry is broken for perturbations around that vacuum even though the entire Lagrangian retains that symmetry. Overview By definition, spontaneous symmetry breaking requires the existence of physical laws (e.g. quantum mechanics) which are invariant under a symmetry transformation (such as translation or rotation), so that any pair of outcomes differing only by that transformation have the same probability distribution. For example if measurements of an observable at any two different positions have the same probability distribution, the observable has translational symmetry. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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