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Topic: Particle theories

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	Olympus Microscopy Resource Center: Physics of Light and Color - Light: Particle or a Wave?
		Huygens' theory of light refraction, based on the concept of the wave-like nature of light, held that the velocity of light in any substance was inversely proportion to its refractive index.
		The ether theory lasted at least until the late 1800s, as evidenced by Charles Wheatstone's proposed model demonstrating that ether carried light waves by vibrating at an angle perpendicular to the direction of light propagation, and James Clerk Maxwell's detailed models describing the construction of the invisible substance.
		In fact, the particle theory is also not adequate to explain interference and diffraction, effects that would be later found to be manifestations of the same phenomenon.
	www.olympusmicro.com /primer/lightandcolor/particleorwave.html (3286 words)

	Supersymmetry - Wikipedia, the free encyclopedia
		In particle physics, supersymmetry is a hypothetical symmetry that relates bosons and fermions.
		For string theory to be consistent, supersymmetry appears to be required at some level (although it may be a strongly broken symmetry).
		In particle theory, supersymmetry is recognized as a way to stabilize the hierarchy between the unification scale and the electroweak scale (or the Higgs particle mass), and can also provide a natural dark matter candidate.
	en.wikipedia.org /wiki/Supersymmetry (2283 words)

	Taking the Particle out of Particle Physics
		Particle physics is the most fundamental area of science in that its goal is to reduce the wonderful diversity and complexity of our universe to a few simple mathematical laws.
		As a result, whereas in the nonrelativistic theory we find that the square of the spatial momentum is proportional to the energy, in the relativistic theory the square of the spacetime momentum is a constant, the square of the rest mass.
		Although quantization of the particle is straightforward, consistency of the quantization of the string introduces a particularly unusual feature: The dimension of spacetime is determined to be 26 for the simplest string, and 10 or 2 for those with extra degrees of freedom.
	insti.physics.sunysb.edu /~siegel/quo.html (1777 words)

	Quantum field theory - Wikipedia, the free encyclopedia
		Relativistic quantum field theories are indispensable in particle physics (see the standard model), although they are known to arise as effective field theories in condensed matter physics.
		QM deals with particles and one of the properties of a particle is its position as a function of time and in QM, this becomes the position operator as a function of time (it's constant in the Schrodinger picture and varying in the Heisenberg picture).
		As described in the article on identical particles, quantum mechanical particles of the same species are indistinguishable, in the sense that the state of the entire system must be symmetric (bosons) or antisymmetric (fermions) when the coordinates of its constituent particles are exchanged.
	en.wikipedia.org /wiki/Quantum_field_theory (3494 words)

	Particles vs. strings
		In light of the huge amount of propaganda and confusion regarding string theory, it might be useful to consider the relative merits of the descriptions of the fundamental constituents of matter as particles or strings.
		A string that is a composite of particles (as for hadrons) might be necessary to solve the D=4 problem, which may be the root of all string theory's problems.
		Thus particle theory and string theory would be unified, and this unification would be a requirement to solve the problems of both theories.
	insti.physics.sunysb.edu /~siegel/vs.html (1419 words)

	Open Questions: Supersymmetry
		This is because gravity requires a particle having the mathematical properties of a "tensor", which are different from those of a scalar boson (spin 0) or a vector boson (spin 1).
		Quantum theory and the theory of general relativity (which is all about gravity) were the two greatest accomplishments of 20th century physics.
		Since particles can be created only together with their antiparticles (which have the same mass), at least twice as much energy as that contained in a particle's mass must be available.
	www.openquestions.com /oq-ph007.htm (9203 words)

	Theory: Quantum Mechanics
		Quantum theory is the language of all particle theories.
		Because the particles in high-energy experiments travel at close to the speed of light, particle theories are relativistic quantum field theories.
		All particles have properties that are wave-like (such as interference) and other properties that are particle-like (such as localization).
	www2.slac.stanford.edu /vvc/theory/quantum.html (1038 words)

	Introduction
		Adopting a wave theory, Huygens was able to derive the laws of reflection and refraction and to explain double refraction in calcite as well.
		All these examples of the photon, or particle, model of light indicated that light could be treated as a particular kind of matter, possessing both energy and momentum.
		On the other hand, electrons usually behaved like particles, as observed in the point-like scintillations of a phosphor exposed to a beam of electrons; in other situations they were found to behave like waves, as in the diffraction produced by an electron microscope.
	physics.tamuk.edu /~suson/html/4323/intro.html (1192 words)

	Theory: SLAC Virtual Visitor Center
		The name given to the theory that best incorporates all observations to date in the particle realm is "the Standard Model".
		Gravitational interactions have yet to be successfully incorporated into the quantum field theory and are a tiny effect in high energy particle collisions, so are ignored in the Standard Model.
		Particle physics theories are written in mathematical language called relativistic quantum field theory.
	www2.slac.stanford.edu /vvc/theory.html (210 words)

	Open Questions: Superstring Theory
		Although string theories automatically avoided the sorts of problems which typically introduce infinities into point particle theories, it is still necessary to prove that string theories don't have new kinds of inifinities of their own.
		In this theory, however, the strings are oriented, and the fermionic vibrations move in one direction around the loop, while the bosonic vibrations move in the opposite direction.
		Particles with a left-handed spin behave differently from particles with a right-handed spin when the weak force is involved.
	www.openquestions.com /oq-ph001.htm (16723 words)

	Unification and distance scales
		The best candidate for such a theory is unitary group SU(5), which would give 24 gauge bosons mediating the single unified force, but there are also other GUT models based on other groups, such as the orthogonal group SO(10), which would give 45 gauge bosons and contain the SU(5) theory as a subgroup.
		However, these are supersymmetric theories in ten spacetime dimensions, so the symmetry breaking scheme also has to be involved with breaking the supersymmetry (because fermions and bosons don't come in pairs in the real world) and dealing with the extra six space dimensions in some manner.
		But -- in string theory, at the level of perturbation theory where the physics is most understood -- the scalar potentials seem to be flat in all directions and hence the scalar fields all remain massless.
	superstringtheory.com /experm/exper3a2.html (1002 words)

	Prevailing Theories (Site not responding. Last check: 2007-11-02)
		His theories encouraged particle physicists to examine major ideas in diverse ways and to seek out new theories that crossed distinct genres of physics research.
		Because new theories are meaningless until they are published and debated, the three colleagues submitted an article for publication in Nuclear Physics, a leading international journal.
		Every particle in nature is one of two subatomic varieties, either a boson or a fermion.
	www.it.umn.edu /news/inventing/1999_Fall/ptheories.html (1972 words)

	High Energy Physics (Site not responding. Last check: 2007-11-02)
		In addition, we are employing particle physics to explain interesting astrophysical and cosmological phenomena as well as applying astrophysical and cosmological observations to test and constrain particle theories.
		This includes studying particles that are produced in these collisions, such as the recently discovered top-quark, refining previous measurements to set limits on how well the standard model of particle physics agrees with data.
		These gauge theories are Abelian in the case of electrodynamics (photons do not interact directly with each other), and are non-Abelian in the case of chromodynamics, the theory of the strong subnuclear force (gluons couple directly with each other).
	www.nhn.ou.edu /grbroch/node11.html (2665 words)

	Particle Theories
		Is probability theory the "ultimate" explanation for the "states" of elementary particles, or will future scientists find descriptions or models in terms of something more fundamental than current models that does not use probability theory?
		I mean, a physical theory can't possibly encompass a description of its own limitations, any more than you can see what you can't see because it's behind you.
		You would hardly doubt that a horse could never comprehend calculus -- the most correct theory of mechanics may analogously be beyond the grasp of homo sapiens.
	www.newton.dep.anl.gov /askasci/phy99/phy99x17.htm (617 words)

	HORIBA Particle Characterization Products -- Global home page
		Horiba's expertise in the area of particle characterization is both broad and deep.
		Using unique incoherent light scattering theory, the CRYSTALSIZER is able to measure dry powders from 0.7 to 2500 microns.
		Particles in Nanometer to Millimeter Scales Measured in One Minute The Broadest Measurement Range (10 nm to 3 mm) in the Industry
	www.horiba-particle.com (386 words)

	Conduction At The Atomic Level (Site not responding. Last check: 2007-11-02)
		According to classical theory, an orbiting electron would continuously lose energy by radiation and spiral into the nucleus.
		The Strong Nuclear Forces are accounted for between the large particle atomic interaction screw-bolt connections (proton to neutron).
		They are basically the same with regard to the number and type of particles, but the Helix Spiral Field Energy Strength is lesser for the Neutron as compared to the Hydrogen Atom.
	members.aol.com /SEntrprize/elect2.htm (2208 words)

	Citebase - Cosmic Vortons and Particle Physics Constraints
		We estimate the abundances of the ensuing vortons, and thereby derive constraints on the relevant particle physics models from cosmological observations.
		We investigate the cosmological consequences of particle physics theories that admit stable loops of current-carrying string - vortons.
		In particular, we consider chiral theories where a single fermion zero mode is excited in the string core, such as those arising in supersymmetric theories with a...
	www.citebase.org /cgi-bin/citations?id=oai:arXiv.org:hep-ph/9605382 (1191 words)

	Gauge Field Theory (Site not responding. Last check: 2007-11-02)
		The course is an introduction to the gauge field theories of modern Particle Physics.
		Relativistic quantum fields (4 lectures): Classical field theory; electromagnetic waves; Klein-Gordon field; Fourier analysis; second quantization; single-particle and two-particle states; number operator; quantizing the electromagnetic field; vacuum energy and normal ordering; the Casimir effect; complex fields; symmetries and conservation laws; Noether's theorem; phase (gauge) invariance; Dirac field; spin-statistics theorem.
		Gauge theory of electroweak interactions (3 lectures): Gauge symmetry in QED; non-Abelian gauge symmetry; weak interactions; electroweak interactions; Higgs mechanism; parameters of the Standard Model; spontaneous symmetry breaking; properties of the Higgs boson.
	www.hep.phy.cam.ac.uk /theory/webber/GFT (347 words)

	Theories of particle physics: Literature
		Peskin and Schröder: An Introduction to Quantum Field Theory (95) A very good book to study the fundamentals of quantum field theory, including the quantization by operator formalism.
		Quigg: Gauge theory of the Strong, Weak and Eletromagnetic Interactions (83).
		Particle Data Group: Review of Particle Properties C. Caso et al, The European Physical Journal C3 (1998) 1.
	www.cis.hut.fi /kaip/hitu/literature.html (512 words)

	ECS EPrints Service - Gauge Theories in Particle Physics: A Practical Introduction: Volume 2 Non-Abelian Gauge ... (Site not responding. Last check: 2007-11-02)
		Gauge Theories in Particle Physics: A Practical Introduction: Volume 2 Non-Abelian Gauge Theories: Qcd and the Electoweak Theory
		Aitchison, I. and Hey, A. Gauge Theories in Particle Physics: A Practical Introduction: Volume 2 Non-Abelian Gauge Theories: Qcd and the Electoweak Theory.
		Gauge Theories in Particle Physics: A Practical Introduction: Volume 2 Non-Abelian Gauge Theories: Qcd and the Electoweak Theory (deposited 12 March 2004)
	eprints.ecs.soton.ac.uk /10606 (151 words)

	Particle Physics Theories (Site not responding. Last check: 2007-11-02)
		The ìStandard Modelî to understand these and a suite of other
		fundamental particles of nature has been developed and is found
		Although there are variations, this whole class of theories are
	www.ucolick.org /~koo/2001_lectures/lecture13/tsld013.htm (44 words)

	Gauge Theories in Particle Physics: Ian J. R. Aitchison: ISBN 0750308648
		Gauge Theories in Particle Physics: Ian J. Aitchison: ISBN 0750308648
		Gauge Theories in Particle Physics: A Practical Introduction From Relativistic Quantum Mechanics to Qed, Vol.
		This book is part of the Graduate Student Series in Physics.
	www.bestwebbuys.com /0750308648 (143 words)

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