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Topic: Weak isospin

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	Quarks
		Quarks undergo transformations by the exchange of W bosons, and those transformations determine the rate and nature of the decay of hadrons by the weak interaction.
		Conservation of strangeness is not in fact an independent conservation law, but can be viewed as a combination of the conservation of charge, isospin, and baryon number.
		Isospin and either hypercharge or strangeness are the quantum numbers often used to draw particle diagrams for the hadrons.
	hyperphysics.phy-astr.gsu.edu /hbase/particles/quark.html (1357 words)

	Theory: Isospin Invariance (SLAC VVC)
		Isospin invariance follows from the fact that the strong interactions are independent of quark type, and so do not distinguish up quarks from down quarks.
		Isospin is the invariance that relates strong interaction processes or states that differ only by replacing some number of protons by an equal number of neutrons.
		However the mathematics of isospin is similar to the mathematics of spin for spin 1/2 particles, and this is where the spin part of the name arose.
	www2.slac.stanford.edu /VVC/theory/isospin.html (481 words)

	Isospin - Wikipedia, the free encyclopedia
		In physics, and specifically, particle physics, isospin (isotopic spin, isobaric spin) is a symmetry of the strong interaction as it applies to the interactions of the neutron and proton.
		Isospin symmetry remains an important concept in particle physics, and a close examination of this symmetry historically lead directly to the discovery and understanding of quarks and of the development of Yang-Mills theory.
		To be precise, the isospin symmetry is given by the invariance of the Hamiltonian of the strong interactions under the action of the Lie group SU(2).
	en.wikipedia.org /wiki/Isospin (1024 words)

	Weak isospin - Wikipedia, the free encyclopedia
		The weak isospin in theoretical physics parallels the idea of the isospin under the strong interaction, but applied under the weak interaction.
		But, in the same way that isospin creates hadron multiplets of particles that are indistinguishable under the strong interaction, all elemental fermions can be grouped in multiplets that behave the same under the weak interaction.
		Thus, fundamental fermions are grouped in pairs of particles that behave the same under the weak interaction, and differ from other pairs on their masses (i.e., they belong to different generations of matter).
	en.wikipedia.org /wiki/Weak_isospin (335 words)

	Quark
		The magnitude of flavour changing in the weak interaction is encoded into a structure called the CKM matrix.
		With the proof of asymptotic freedom in QCD in 1973 by David Gross, Frank Wilczek and David Politzer the connection was firmly established.
		The discovery in 1975 of the meson which came to be called the J/ψ led to the recognition that it was made of a charm quark and its antiquark.
	www.wikipediaondvd.com /nav/art/8/l.html (2161 words)

	A violation of CP symmetry in B meson decays
		One of the ingredients of the model is the electroweak theory, unifying electromagnetism and weak interactions, which is based on an internal symmetry called the weak-isospin symmetry.
		Quarks experience both weak and strong interactions and are the fundamental constituents of the strongly interacting particles, the hadrons.
		The strength of this transition is quite weak, which is one of the reasons why B mesons have relatively long lifetimes (1.5 picoseconds) despite their large mass (approximately 5 times that of the proton).
	www.europhysicsnews.com /full/15/article4/article4.html (3878 words)

	Weak Axis (Site not responding. Last check: )
		As a symmetrical particle chart could not be created using strangeness, hypercharge or isospin, I have defined a quantized property that seems to be more fundamentally associated with the weak force.
		The "Weakness Axis" indicates what I call the "neutrino number" composition of the particles, minus one for the bottom cell, zero for the middle cell, and plus one for the top cell, in each group.
		The bipolarity seems to relate to clockwise or counterclockwise angular displacement, while the differences in charge, baryon number and weakness seems to be related to topology or orientation.
	home.earthlink.net /~tdp/weak_axis.html (428 words)

	Weak Decays (1981)
		is a unitary matrix of mixing angles which connects the quark fields participating in weak interactions to the mass eigenstates.
		``decays'' arise from violations of weak isospin invariance by mass differences between pairs of quarks (and leptons) in the same weak isomultiplet (e.g.,
		quarks presumably arise primarily from weak interaction effects (via the Higgs mechanism, etc.), and must be inserted as explicit bare mass terms in the QCD Lagrangian.
	stephenwolfram.com /publications/articles/particle/81-weak/3/text.html (338 words)

	Weak hypercharge -
		Weak hypercharge is twice the difference between the electrical charge and the weak isospin.
		where Q is the electrical charge (in elementary charge units), $I^W_z$ is the third component of the weak isospin, and $Y^W$ is the weak hypercharge.
		Given that weak isospin is 1/2 for all left-handed fermions (and 0 for all right-handed fermions), all weak isospin doublets will have an average charge
	psychcentral.com /psypsych/Weak_hypercharge (198 words)

	Hypercharge and Weak Isospin
		There is a close relation between weak isospin and Heisenberg's original isospin: in particular, the isospin of a nucleon is the sum of the weak isospins of the three quarks it is made of.
		However, weak isospin is now considered to be important for the weak rather than the strong nuclear force.
		on this irrep, corresponding to weak isospin and hypercharge.
	math.ucr.edu /home/baez/qg-spring2003/hypercharge (1190 words)

	Significance of isospin and hypercharge
		Isospin and either hypercharge or strangeness are the quantum numbers often used to draw particle diagrams for the hadrons.
		Weak isospin is the SU(2) type symmetry between the two objects that a weak force W+/- converts between.
		Thus the photon is a mixture of a weak isospin and weak hypercharge interaction.
	www.physicsforums.com /showthread.php?t=91808 (2425 words)

	Standard Model Summary
		The gauge bosons of the weak force are called the W-and Z-bosons, and the gauge bosons of the strong force are referred to as gluons.
		In the Standard Model, the theory of the electroweak interaction (which describes the weak and electromagnetic interactions) is combined with the theory of quantum chromodynamics.
		All of these theories are gauge theories, meaning that they model the forces between fermions by coupling them to bosons which mediate (or "carry") the forces.
	www.bookrags.com /Standard_Model (2754 words)

	Properties of Quarks
		When the orientation of an isospin vector is considered, it is in some hypothetical space, not in terms of the x, y and z axes of normal co-ordinates.
		The strong interaction eigenstates are the u, d, s, c, b and t quarks, with well-defined isospin, strangeness etc. The eigenstates of the weak interaction, which does not conserve I, S etc., are said to be those of “weak isospin” T.
		Physically, this is revealed during weak decays in the relative probability of producing hadrons containing the respective quarks.
	www.shef.ac.uk /physics/teaching/phy304/propquark.html (1266 words)

	Electro-weak:
		In particle physics, the electroweak interaction is the unified description of two of the four fundamental interactions of nature: electromagnetism and the weak interaction.
		For contributions to the unification of the weak and electromagnetic interaction between elementary particles, Abdus Salam, Sheldon Glashow and Steven Weinberg were awarded the Nobel Prize in Physics in 1979.
		The corresponding gauge bosons are the photon of electromagnetism and the W and Z bosons of the weak force.
	pandapedia.com /wiki/Electro-weak (594 words)

	Open Questions: Higgs Physics
		Unfortunately, with the weak force we know experimentally that the carrier particles have mass and that there is limit to the range of the force.
		What this means is simply that the total number of leptons involved in a weak interaction does not change as a result of the interaction, as long as leptons are each counted with a positive number, and their antiparticles are counted with a negative number.
		The particles differ in a quantity called "weak isospin", because it is quite analogous to the quantity called "isospin" that Heisenberg introduced in 1932 to differentiate the two nucleons (protons and neutrons).
	www.openquestions.com /oq-ph008.htm (9061 words)

	Grand Unification Theory
		One is the weak interaction, which is responsible for the beta decay of radioactive materials.
		To discuss the weak force, it is necessary to introduce another property of the elementary particles; spin angular momentum (spinning on an internal axis, like the earth or top) also called handedness of a particle.
		The doublets of weak isospin that quarks and leptons form (Table 2) is a two-ness.
	www.irfi.org /articles/articles_51_100/grand_unification_theory.htm (2010 words)

	Quark
		The magnitude of flavour changing in the weak interaction is encoded into a structure called the CKM matrix.
		The scheme grouped together particles with isospin and strangeness using a unitary symmetry derived from current algebra, which we today recognise as part of the approximate chiral symmetry of QCD.
		With the proof of asymptotic freedom in QCD in 1973 by David Gross, Frank Wilczek and David Politzer the connection was firmly established.
	www.sfcrowsnest.com /scifinder/a/Quark.php (2034 words)

	Open Questions: The Standard Model
		The weak force is felt by all particles in the table, as is gravity.
		Bosons having a spin of 1 (or -1) mediate the forces of electromagnetism (the photon), the weak force (W and Z bosons), and the strong force (gluons).
		By analogy with the property of isospin that distinguishes protons and neutrons, the property which distinguishes particles related by the weak nuclear force is called "weak isospin".
	www.openquestions.com /oq-ph005.htm (12053 words)

	The Elementary Particles
		A particle's mass determines how it responds to gravity, the electric charge determines its response to electromagnetism, its strong charge determines its response to the strong force, and its weak charge determines its response to the strong force.
		This topic is discussed more fully in The Four Fundamental Forces; however, a discussion of fundamental particles would be incomplete without a brief mention of the messenger particles associated with each force.
		It seems strange to many people that the electric, strong, and weak charges conform to such regular patterns while the particles' masses vary so widely.
	library.thinkquest.org /27930/particles.htm (708 words)

	GBSMCOPY.nb
		Among the physical properties explained are the mass ratios of the six leptons and eight quarks, the origin of the left-handed preference by the weak interaction, the geometrical source of color symmetry, and the zero neutrino masses.
		In summary, for the case of weak isospin in the unitary plane, it appears that nature had no choice but to divide the weak isospin states into left-handed doublets and right-handed singlets.
		The weak charge was assigned by the Standard Model to the basis states in the unitary plane where the weak interaction rotates the fundamental fermion particle states.
	www.sciencegems.com /gbsm.html (9679 words)

	Eotvos and Novel Equivalence Principle Tests
		Weak interactions violate parity conservation and violate the remainder.
		Choose a z-axis position such that a silicon is centered at the same unit cell position in both space groups P3 21 and P3 Spatial distribution of the four oxygens around that silicon then define lattice chirality.
		The "extra" six dimensions loosely comprise one charge dimension, two isospin dimensions, and three color dimensions.
	www.mazepath.com /uncleal/eotvos.htm (7753 words)

	Highlights from Run 1
		During the 1960s and 70s, it was recognized that the electromagnetic and weak forces could be described through a unified picture, and the theory of electroweak interactions was born.
		The absence of a "weak isospin" partner represented a theoretical discomfort that was only dispelled with the later discovery of its missing companion, the top quark (see Section 3).
		This delicate placement in the mass scale, together with the tendency of quarks to interact mainly with their weak isospin partners, conspire to give the bottom quark yet another set of very welcome properties.
	d0server1.fnal.gov /projects/results/runi/highlights/highlight_document/Highlights_v18_final.html (8678 words)

	Course
		Topics include quark models; strong, electromagnetic and weak interactions; isospin, strangeness, consevation laws and symmetry principles; systemaatics of nuclear properties, nuclear radioactivity, nuclear models and reactions.
		The structure of nuclei, and nuclear phenomena such as a, b and g radioactivity, are interrelated, with emphasis on the quantum-mechanical nature of nuclear phenomena.
		The forces important at the subatomic level, strong, electromsgnetic and weak, are introduced.
	www.physics.uoguelph.ca /www_physics/single_course.php?idx=7 (230 words)

	No Title
		The SU(2) isospin symmetry could be extended to SU(3) -flavour and later to SU(3) -colour which lead to the formulation of QCD, the theory of strong interactions.
		Weak interactions, which are based on SU(2) -weak isospin, are special in the sense that they violate most symmetries.
		CP violation, which is established in the kaon system even if the effects are small, might play an important role in sheding light on the mysterious origin of matter-antimatter asymmetry in the universe.
	www.fys.uio.no /epf/hf_2000/Hera_B_Topics (747 words)

	Indirect Evidence for the Existence of the Tau Neutrino
		Fairly recently, the ARGUS collaboration demonstrated that the tau neutrino spin is 1/2 [Alb92] (under the assumption that the tau neutrino is massless) by measuring the spin alignment of the
		The weak neutral current, unlike the charged current, is not purely left-handed.
		It therefore seems reasonable to accept its existence: we shall assume it is the third generation neutral lepton, weak isospin partner of the tau.
	www.fynu.ucl.ac.be /librairie/theses/gustaaf.brooijmans/node7.html (1303 words)

	The Standard Model ... and Beyond
		What leads us to recognize the pairs is that a left-handed electron can be transformed into its neutrino (and vice versa) by the action of the weak force particle the W boson.
		One of the striking features of our world is that left-handed and right-handed particles are different: the left-handed ones come in the pairs we have just seen, but their right-handed counterparts are immune from the familiar weak interaction.
		We do not know whether there is no right-handed weak interaction or whether--like the interaction that exchanges quarks and leptons--our instruments have just not been sensitive enough to detect it.
	boudin.fnal.gov /~quigg/JGV/EnvPFintro.html (1460 words)

	TOP STUFF (Site not responding. Last check: )
		The bottom quark, the weak isospin partner of the top, was discovered in the late 1970's.
		In the standard model of particle physics the existence of the bottom quark implied that there must also be a top quark.
		The Higgs boson is a hypothetical particle that would explain both how the electromagnetic and weak forces could be united and subsequently broken and explain the origin of mass.
	hep.bu.edu /~kmblack/topinfo.html (826 words)

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