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Topic: Isospin


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In the News (Tue 23 Apr 19)

  
  Isospin - Wikipedia, the free encyclopedia
Isospin (isotopic spin, isobaric spin) is a physical quantity which is mathematically analogous to spin.
Isospin was introduced by Werner Heisenberg to explain the fact that the strength of the strong interaction is almost the same between two protons or two neutrons as between a proton and a neutron, unlike the electromagnetic interaction which depends on the electric charge of the interacting particles.
In the framework of the Standard Model, isospin invariance of the strong interaction is a result of the fact that particles differing only in the replacement of an up quark for a down quark (such as protons (uud) and neutrons (udd)) behave the same, since strong interactions are independent of the flavor of particles.
en.wikipedia.org /wiki/Isospin   (311 words)

  
 Isospin   (Site not responding. Last check: 2007-11-06)
Isospin was introduced by Werner Heisenberg to explain the fact that the strong interaction was almost the same between two proton s or two neutron s as it was between a proton and a neutron.
In the framework of the Standard Model, isospin invariance of the strong interaction is a result of the fact that particles differing only in the replacement of an up quark for a down quark (such as protons (uud) and neutrons (udd)) behave the same, since strong interactions are independent of the flavor of particle s.
Isospin invariance is absent in electromagnetic and weak interaction s since they do depend on quark flavour.
www.serebella.com /encyclopedia/article-Isospin.html   (290 words)

  
 Isospin   (Site not responding. Last check: 2007-11-06)
Isospin was introduced by Werner Heisenberg to explain the fact that the strength of the strong interaction is almost the same between two protons or two neutrons as between a proton and aneutron, unlike the electromagnetic interaction which depends onthe electric charge of the interacting particles.
In the original formulation of Yang-Mills theory, protons and neutrons were described as twocomponents of an isospin doublet, belonging to the fundamental representation of SU(2), and interacting bymeans of the SU(2) gauge bosons.
In the framework of the Standard Model, isospin invariance of the strong interaction is a result of the fact that particles differingonly in the replacement of an up quark for a down quark (such as protons (uud) and neutrons (udd)) behave the same, sincestrong interactions are independent of the flavor of particles.
www.therfcc.org /isospin-81336.html   (284 words)

  
 Isospin -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-11-06)
Isospin (isotopic spin, isobaric spin) is a physical quantity which is mathematically analogous to (A swift whirling motion (usually of a missile)) spin.
Heisenberg's idea was that protons and neutrons were essentially two (The way something is with respect to its main attributes) states of the same particle, the (A constituent (proton or neutron) of an atomic nucleus) nucleon, analogous to the 'up' and 'down' states of a (A swift whirling motion (usually of a missile)) spin-1/2 particle.
Isospin invariance is absent in (Click link for more info and facts about electromagnetic) electromagnetic and ((physics) an interaction between elementary particles involving neutrinos or antineutrinos that is responsible for certain kinds of radioactive decay; mediated by intermediate vector bosons) weak interactions since they do depend on quark flavour.
www.absoluteastronomy.com /encyclopedia/i/is/isospin.htm   (249 words)

  
 Particle Interactions and Conservation Laws
Isospin is a term introduced to describe groups of particles which have nearly the same mass, such as the proton and neutron.
This doublet of particles is said to have isospin 1/2, with projection +1/2 for the proton and -1/2 for the neutron.
Isospin is associated with the fact that the strong interaction is independent of electric charge.
hyperphysics.phy-astr.gsu.edu /hbase/particles/parint.html   (1185 words)

  
 Theory: Isospin Invariance
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.
Isospin is a symmetry that relates members of a set of isobars.
www2.slac.stanford.edu /vvc/theory/isospin.html   (445 words)

  
 ISOSPIN   (Site not responding. Last check: 2007-11-06)
Isospin ist eine mit einer inneren Symmetrie verbundene Quantenzahl in der Theorie der Elementarteilchen.
Eingeführt wurde der Isospin von Werner Heisenberg, um die beiden Kernbestandteile, Proton (p) und Neutron (n), als Aspekte oder Zustände eines einzigen Teilchens, des Nukleons ansehen zu können.
Dann ist das Proton ein Nukleon mit Isospin +1/2, während ein Neutron ein Nukleon mit Isospin -1/2 ist.
www.toonorama.com /encyclopedia/I/Isospin   (267 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 undistinguishable under the strong interaction, all elemental fermions can be grouped in multiplets that behave the same under the weak interaction.
There is also a weak isospin conservation law: all weak interactions must preserve the weak isospin.
en.wikipedia.org /wiki/Weak_isospin   (325 words)

  
 Flavour (particle physics) - Wikipedia, the free encyclopedia
The term "flavour" was first coined for use in the quark model of hadrons in 1968.
A name for the set of quantum numbers related to isospin, hypercharge and strangeness is said to have been found on the way to lunch by Murray Gell-Mann and Harald Fritzsch when they passed a Baskin-Robbins advertising 31 flavours.
Weak isospin and weak hypercharge are gauged in the standard model.
en.wikipedia.org /wiki/Flavor_(particle_physics)   (1091 words)

  
 Doctoraatsverdediging
Een belangrijk onderdeel van de experimentele kernfysica is het onderzoek naar en het verkrijgen van inzicht in the fundamentele eigenschappen van exotische kernen waarin de verhouding van het aantal protonen tot het aantal neurtronen sterk afwijkt van die in stabiele kernen.
Isospin is een belangrijk concept in de hadronfysica en wordt gebruikt in de kernfysica als belangrijk middel om hadronische- en kerntoestanden te beschrijven.
Isospin is an important concept of hadron physics and was introduced in nuclear physics as an important tool for the classification of nuclear and hadronic states.
www.kuleuven.ac.be /doctoraatsverdediging/cm/3E01/3E010651.htm   (773 words)

  
 [No title]
Noting the near-degeneracy of protons and neutrons suggested the initial SU(2) isospin symmetry; but exploration of collision products soon made it clear that were not just 2, but 8 nearly degenerate light spin-1/2 particles, whose masses (degenerate within a factor of 20%) were well-separated from the masses of heavier spin-1/2 particles.
Plotting their isospin and hypercharge quantum numbers gave a diagram with striking geometric symmetry: a perfect hexagon, with particle quantum numbers at the vertices, as well as two particles with quantum numbers at the origin.
Within these diagrams were grouped particles from different isospin representations: for spin-1/2 particles, the isospin-1/2 proton-neutron doublet; the isospin-1 \Sigma triplet, the isospin-1/2 \Xi doublet; and the isospin-0 \Lambda singlet.
www.physics.emory.edu /faculty/benson/380-96/notes/39.txt   (785 words)

  
 No Title
We then introduced isospin symmetry: the invariance of nuclear forces under rotations that mix the proton and neutron fields.
Consequences of isospin symmetry are that 1) all strong interaction terms should be isospin invariant; and 2) particles should fall into degenerate multiplets, the 2j+1-dimensional representations of isospin SU(2).
We note that the isospin and hypercharge symmetry found here emerge for initially unknown and seemingly independent reasons; we will soon find that they are just aspects of a larger symmetry group of the strong interactions.
www.emory.edu /PHYSICS/Faculty/Benson/380-96/notes/38/38.html   (475 words)

  
 Isospin -- L'Isospin (spin isotopico, spin isobarico) è una quantità fisica ...   (Site not responding. Last check: 2007-11-06)
Isospin -- L'Isospin (spin isotopico, spin isobarico) è una quantità fisica...
Questa proprietà venne battezzata isospin, una quantità vettoriale che si conserva nelle reazioni tra particelle e che è caratteristica delle interazioni in cui interviene la forza nucleare forte, impiegata quindi nella descrizione dei processi tra nucleoni.
I generatori di isospin sono descritti dalle matrici di Pauli.
isospin.it.tracking24.net   (430 words)

  
 Encyclopedia: Isospin
In physics, spin is an intrinsic angular momentum associated with microscopic particles.
In mathematics, a Lie group is an analytic real or complex manifold that is also a group such that the group operations multiplication and inversion are analytic maps.
The Standard Model of Fundamental Particles and Interactions The Standard Model of particle physics is a theory which describes the strong, weak, and electromagnetic fundamental forces, as well as the fundamental particles that make up all matter.
www.nationmaster.com /encyclopedia/Isospin   (1015 words)

  
 isospin --  Encyclopædia Britannica
The families of similar particles are known as isospin multiplets: two-particle families are called doublets, three-particle families are called triplets, and so on.
As early as 1920, when Rutherford named the proton and accepted it as a fundamental particle, it was clear that the electromagnetic force was not the only force at work within the atom.
In particular, values of mass, electric charge, spin, isospin, and strangeness gave physicists a means of classifying the strongly interacting particles—or hadrons—and of establishing a hierarchy of relationships between them.
www.britannica.com /eb/article-9042967?tocId=9042967   (352 words)

  
 Untitled Document
ISOSPIN is the first proposal that uses the new 4pi device CHIMERA mounted in its complete configuration at the LNS in Catania.
The aim is to explore the behaviour of the nuclear matter EOS by studying heavy ion collisions at intermediate energies.
In particular the role of isospin degree of freedom in the EOS will be studied using different combination of beams and targets with different isotopic ratio, by means of the isotopic identification of the detected IMF.
www.infn.it /esperimenti/esperimentien.php?gruppo=3&sigla_naz=ISOSPIN   (451 words)

  
 PHYS146 Notes Spin and Isospin
Along the horizontal axis, particles are labelled by a quantity called isospin, I, modelled after the behavior of spin.
Isospin is defined the way it is because it is conserved in all strong interactions.
It is also known that the smallest groups (except for the group of one particle) involving quantities like isospin and hypercharge contain three members (triplets).
www.udel.edu /mvb/PS146htm/146noqu.html   (2760 words)

  
 symmetry and conservation laws   (Site not responding. Last check: 2007-11-06)
It was not until the discovery of quarks that the cause of isospin symmetry was understood.
This means that the total isospin and its projection were constants of motion if these two forces were responsible for the dynamics of the system.
The concept of isospin was important as a first step in realizing that there were other symmetries in nature than the classical space-time symmetries.
www.calstatela.edu /faculty/kaniol/f2000_lect_nuclphys/lect2/sym_cons.htm   (507 words)

  
 CERN Courier - Neutral currents and other h - IOP Publishing - article
But an isospin 0 state of two pions is necessarily a neutral state, and therefore the decay of the K
Smart schemes were proposed, and I may mention the Schizon theory of Lee and Yang in which the vector bosons sometimes behaved as isospin triplets and sometimes as isospin doublets.
Trying to explain the problems of such things as isospin selection rules and neutral vector bosons to that audience was simply a waste of time.
www.cerncourier.com /main/article/43/5/21   (1497 words)

  
 Isospin Correlations in High-Energy Heavy-Ion Collisions (ResearchIndex)   (Site not responding. Last check: 2007-11-06)
Abstract: We study the posibility of large isospin fluctuations in high-energy heavy-ion collisions by assuming that pions are produced semiclassically both directly and in pairs through the isovector channel.
The leading-particle effect and the factorization property of the scattering amplitude in the impact parameter space are used to define the classical pion field.
0.4: Isospin Coherence and Final-State Scattering of Disoriented..
citeseer.ist.psu.edu /101264.html   (223 words)

  
 Kent Gifford's Summer Research Report   (Site not responding. Last check: 2007-11-06)
The genesis of our research is to establish that isospin is only an approximate quantum number and to discover states seen in isospin reactions.
After seeing that the isospin forbidden state does indeed exist, the goal is to identify the spins and parities of the compound nucleus.
In sum, the goal of uncovering the isospin forbidden state in the 24Mg(d,alpha_2)22Na was reached.
www.hope.edu /academic/physics/reu96/gifford.html   (483 words)

  
 isospin mixing calculations   (Site not responding. Last check: 2007-11-06)
The calculations of the isospin mixing of the isobaric anologue states (IAS) in various nuclei are done in the context of the nuclear shell model.
As long as the isospin is a good quantum number the Fermi strength is given by the simple formula
For the recent calculations of the isospin mixing and the isospin-forbidden particle emission see e.g.
www.phys.jyu.fi /research/igisol/isospin_mixing.html   (368 words)

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