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Topic: Chiral symmetry

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In the News (Wed 24 Apr 19)

  Chiral Compound::CHEM-ONLINE.org::
Chiral molecules are sometimes referred to as being "dissymmetric"; chirality and dissymmetry being one in the same.
A molecule is chiral (that is, not chiral) if and only if it has an axis of improper rotation, that is, an n-fold rotation (rotation by 360°/n) followed by a reflection in the plane perpendicular to this axis which maps the molecule on to itself.
Chirality is of critical importance in chemistry and unites the traditionally-defined subdisciplines of inorganic chemistry, organic chemistry and physical chemistry.
www.chem-online.org /chiral-compound.htm   (0 words)

 Chiral honeycomb
A theoretical and experimental investigation is conducted of a two-dimensionally chiral or noncentrosymmetric honeycomb.
As for structural symmetry, the honeycomb structure is invariant to 60 deg.
Young's moduli of chiral honeycomb depend upon the L/r ratio, hence the R/r ratio; the bending or buckling behavior of the ligaments, hence the strain ranges for which linear elastic theory will apply, can be expected to depend on this ratio.
silver.neep.wisc.edu /~lakes/PoissonChiral.html   (0 words)

 Symmetry Axes
All the symmetry axes of a polyhedron necessarily intersect at a common point at the center of the object.
Some other polyhedra with the same thirteen symmetry axes are the cuboctahedron (in which the 2-fold axes pass through the vertices) and the rhombicuboctahedron (in which each axis goes through the center of two of the 26 faces).Yet another is the snub cube.
The 2-fold axes of the cube are not axes of symmetry of the tetrahedron.
www.georgehart.com /virtual-polyhedra/symmetry_axes.html   (0 words)

 Chiral Symmetry Breaking
I derived an effective action for the low-energy degrees of freedom in a model in which a combination of gauge and four-fermion couplings is near a critical value for spontaneous chiral symmetry breaking.
In recent years, there has been a controversy over whether the chiral phase transition in 2+1 dimensional QED is first or second order.
We have also extended our analysis to the zero temperature chiral phase transition in 3+1 dimensional SU(N) gauge theories, like QCD, where we found that there is a critical number of fermion flavors (near 4N) above which there is no chiral symmetry breaking.
particle.physics.ucdavis.edu /terning/Physics/chiral.html   (240 words)

 Symmetry in Architecture by Kim Williams, Architect
Chiral symmetry is found in two objects which are each other's mirror image and which cannot be superimposed, such as our hands.
Chiral symmetry in architecture is another way to place visual emphasis on the central element of a composition.
The reason for the change in symmetries is that, when we enter into the rotunda we leave behind the zone of the terrestrial, represented by the horizontal axis, and experience the zone of the celestial, symbolized by the vertical axis.
members.tripod.com /vismath/kim   (4294 words)

 Symmetry in Architecture by Kim Williams, Architect
Chiral symmetry is found in two objects which are each other's mirror image and which cannot be superimposed, such as our hands.
Chiral symmetry in architecture is another way to place visual emphasis on the central element of a composition.
The reason for the change in symmetries is that, when we enter into the rotunda we leave behind the zone of the terrestrial, represented by the horizontal axis, and experience the zone of the celestial, symbolized by the vertical axis.
www.mi.sanu.ac.yu /vismath/kim/index.html   (4294 words)

 The Book Pl@ce: Title Detail
Among the key problems in modern field theory are the formulation of chiral group theories on the lattice and the quantitative understanding of the quark confinement mechanism.
The two topics are closely related by the fact that the chiral nature of the fermions as well as the confinement force are largely topological in origin.
Topology and Chiral Symmetry in QCD With Overlap Fermions, R.g.
www.thebookplace.com /bookplace/display.asp?K=182774498802608&aub=Valya&m=3&dc=3   (262 words)

 Symmetry Axes
A chiral polyhedron such as the snub cube or snub dodecahedron has all the axes of symmetry of its symmetry group, but no planes of symmetry.
three of the planes are orthogonal to the three 4-fold symmetry axes; each such plane is parallel to, and halfway between, two opposite faces of the cube; these three planes are mutually orthogonal.
This is sometimes called pyrite symmetry as it is the symmetry of one form of the mineral pyrite, a not-quite-regular dodecahedron called a pyritohedron.
www.georgehart.com /virtual-polyhedra/symmetry_planes.html   (0 words)

 The Condensed Matter Theory Sector of SISSA
At this energy, the nesting property leads to an additional degeneracy which reflects the so-called chiral symmetry.
Like in high-energy physics, chiral symmetry leads to interesting phenomena such as delocalization of the wave-function as well as the possible occurrence of anomaly terms.
We are now completing a study of the interaction effects in the presence of chiral symmetry.
www.sissa.it /cm/index.php?contents=research/role.htm   (208 words)

 Chiral Symmetry Breaking | Musings
In the former solution, chiral symmetry is unbroken; in the latter, it is broken to
, the theory confines and chiral symmetry is broken.
Above all the lines, chiral symmetry is unbroken and the theory is deconfined.
golem.ph.utexas.edu /~distler/blog/archives/000887.html   (0 words)

 News | Gainesville.com | The Gainesville Sun | Gainesville, Fla.   (Site not responding. Last check: )
In quantum field theory, chiral symmetry is a possible symmetry of the Lagrangian under which the left-handed and right-handed parts of Dirac fields transform independently.
The chiral symmetry transformation can be divided into a component that treats the left-handed and the right-handed parts equally, known as vector symmetry, and a component that actually treats them differently, known as axial symmetry.
is only an approximate symmetry to begin with, therefore the pions are not massless, but have small masses: they are pseudo-Goldstone bosons.
www.gainesville.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=chiral_symmetry   (235 words)

 5th International Workshop on Chiral Dynamics, Theory & Experiment
The purpose of this workshop series is to bring physicists together who are active in this field, as well as those who are interested, to discuss and debate the most recent and future developments in various topics related to the study of Chiral Dynamics.
The workshop traditionally draws a near equal contribution from theorists and experimentalists.
The chiral symmetry present in the QCD Lagrangian along with Goldstone's theorem makes it possible to obtain an approximate QCD solution at low energies using an effective field theory known as chiral perturbation theory (ChPT) or Chiral Dynamics.
www.tunl.duke.edu /events/cd2006   (229 words)

 Chiral Symmetry and the Isospin
The chiral symmetry is therefore broken in two ways: (i) explicitly, by the presence of a symmetry breaking term in the Lagrangian, and (ii) dynamically, as discussed above.
We have identified basic symmetry properties of the QCD solutions, and now we have to go to the next level of description, namely, consider composite objects built of quarks.
Instead, we consider the composite objects to be elementary, and we guess their properties from symmetry considerations of the lower-level fields; otherwise, it would have been too difficult a task.
www.fuw.edu.pl /~dobaczew/maub-42w/node10.html   (0 words)

 Citebase - Realisation of chiral symmetry in the domain model of QCD
Realisation of chiral symmetry in the domain model of QCD
Authors: Kalloniatis, A. Nedelko, S. The domain model for the QCD vacuum has previously been developed and shown to exhibit confinement of quarks and strong correlation of the local chirality of quark modes and duality of the background domain-like gluon field.
chiral symmetry in turn are spontaneously broken with a quark condensate arising due to the asymmetry of the spectrum of Dirac operator.
www.citebase.org /abstract?id=oai%3AarXiv.org%3Ahep-ph%2F0311357   (234 words)

 MIT Physics Faculty: Frank Wilczek
High Density Quark Matter and the Renormalization Group in QCD with Two and Three Flavors: Showing how the renormalization of Fermi liquid parameters in QCD is surprisingly tractable, and identifying the favored couplings.
Color-Flavor Locking and Chiral Symmetry Breaking in High Density QCD: Proposing a fascinating candidate phase for hadronic matter at high density.
Riemann-Einstein Structure from Volume and Gauge Symmetry: A sort of inverse to the Kaluza-Klein construction, realizing gravity as a spontaneously broken gauge theory.
web.mit.edu /physics/facultyandstaff/faculty/frank_wilczek.html   (996 words)

 Citebase - Can Chiral Symmetry Explain the Small Pentaquark Width?
It is shown that the decay amplitude for the Jaffe-Wilczek type pentaquarks is not suppressed by chiral symmetry.
On the other hand, pentaquarks of positive or negative parity built up of an antiquark and two chirally different diquarks in an S-state are stable in the limit of a strictly unbroken chiral symmetry.
Thus, chiral symmetry cannot be the cause of a tiny decay amplitude, even for pentaquarks which are stable in the strict chiral symmetry limit.
www.citebase.org /abstract?id=oai:arXiv.org:hep-ph/0501108   (192 words)

 Flavour (particle physics) - Definition, explanation
This symmetry is global for strong interactions, and gauged for weak interactions.
If all quarks have equal mass, then this chiral symmetry is broken to the vector symmetry of the diagonal flavour group which involves the same transformation to the two helicities of the quarks.
This indicates that QCD has spontaneous chiral symmetry breaking with the formation of a chiral condensate.
www.calsky.com /lexikon/en/txt/f/fl/flavour__particle_physics_.php   (951 words)

chiral - Having different left-handed and right-handed forms; not mirror symmetric; opposite of reflexible.
The cube is not chiral; the snub cube is chiral as these two versions of the snub cube illustrate.
reflexible - Having a plane of mirror symmetry; opposite of chiral.
www.georgehart.com /virtual-polyhedra/glossary.html   (0 words)

The role of chiral symmetry and of quark model structure with SU(6) spin-flavor symmetry are discussed in detail, starting from a pedagogic introduction.
Emphasis is placed on symmetry aspects of the theories.
As an application, the chiral bag model is studied for nucleon structure, where important methods of theoretical physics, mostly related to the semiclassical approach for a system of strong interactions, are demonstrated.
www.worldscibooks.com /physics/4708.html   (178 words)

 Faculty Homepage
This situation is similar to that encountered in minimizing repulsive contacts between point-sites held on the surface of a cylinder: cylindrical phyllotaxis [9].
As these biomolecules can be synthesized from achiral smaller molecules (water, simple hydrocarbons, etc.) a spontaneous breaking of chiral symmetry seems to be necessary in the environment of the prebiotic Earth.
Therefore, the sensitivity to external (chiral) influences of the self-assembled chiral structures is an important quantity to determine.
www.csulb.edu /~gpickett/chiral.html   (939 words)

 Village of First Nations - Links Directory   (Site not responding. Last check: )
Baryon Chiral Perturbation Theory in Lorentz Form - This paper shows that in the presence of massive particles, such as nucleons, the standard low-energy expansion, in powers of meson momenta and light-quark masses, in general converges in only part of the low-energy region
Chiral Dynamics in Nucleons and Nuclei - A review of the implications of the spontaneous chiral symmetry breaking in QCD for processes involving one, two or more nucleons.
Chiral Perturbation Theory - The main elements and methods of chiral perturbation theory, the effective field theory of the Standard Model below the scale of spontaneous chiral symmetry breaking, are summarized
www.firstnations.com /links/index.php?browse=/Science/Physics/Quantum_Mechanics/Quantum_Field_Theory/Chromodynamics/Chiral_Perturbation_Theory   (193 words)

 Chiral condensate - SciForums.com
At high temperatures,, the chiral symmetry is restored.
Disoriented Chiral Condensate (DCC) is a medium where Psi is coherently misaligned.
The lifetime of a disoriented chiral condensate (formed within a heat bath of pions in heavy-ion colliders) is calculated to have a half-life between 4 and 7 fm/c, (depending on pion density).
www.sciforums.com /Chiral-condensate-t-19494.html   (363 words)

 WorldSciNet Archives
The supersymmetric version of the Nambu–Jona-Lasinio model is investigated in connection with the chiral symmetry breaking induced by a soft SUSY breaking term.
It is found that the broken chiral symmetry due to the soft breaking term is restored at suitably high temperature and the symmetry restoration occurs as first-order phase transitions.
The critical temperature at which the chiral symmetry is restored is determined as a function of the strength of the soft breaking term and the field coupling constant.
www.worldscinetarchives.com /cgi-bin/wsnetarchives/article.cgi?jn=mpla&vol=13&yr=1998&issue=1315&art=S0217732398001303.html   (163 words)

 Overlap Fermions
Of the various formulations of lattice QCD, only the overlap Dirac operator respects the important chiral symmetry and has a well defined topological index.
Thus, using overlap fermions is essential when asking questions concerning, for example, the topological properties of the vacuum, chiral symmetry breaking, or using realistic pion masses.
Our current work is aimed at investigating the topological structure of the QCD vacuum and to discover the cause of spontaneous chiral symmetry breaking, something that we believe should be possible on the Blue Gene.
www.fz-juelich.de /zam/csim/qcd/overlap   (167 words)

 Chiral Symmetry   (Site not responding. Last check: )
Chiral Lagrangians, P. Langacker, to be published in the proceedings of the International School of Subnuclear Physics: From Supersymmetry to the Origin of Space-Time, Erice, July 1993.
Symmetry Breaking and the Decays psi' rightarrow Jpsi pio eta and Jpsi rightarrow eta(eta') gamma, P. Langacker, Phys.
Applications of Chiral Perturbation Theory: Mass Formulas and the Decay eta rightarrow 3 pi, P.
dept.physics.upenn.edu /~pgl/precision/references/chiral.html   (137 words)

 [No title]   (Site not responding. Last check: )
I intend to discuss how chiral symmetry can be realised in QCD regularised on the lattice.
In doing so I will outline how such an implementation of chiral symmetry can be used to efficiently simulate dynamical chiral fermions.
As an application of chiral symmetry on the lattice I will report on a calculation addressing the question how topology and spontaneous chiral symmetry breaking are related.
www.physics.gla.ac.uk /~eduardo/seminars/abstracts/Wenger.html   (84 words)

 Chiral Symmetry Breaking in Sodium Chlorate Crystallizaton -- Kondepudi et al. 250 (4983): 975 -- Science
Chiral Symmetry Breaking in Sodium Chlorate Crystallizaton -- Kondepudi et al.
the molecules of the compound are not chiral.
Chiral Sign Induction by Vortices During the Formation of Mesophases in Stirred Solutions.
www.sciencemag.org /cgi/content/abstract/250/4983/975   (0 words)

 LazyWeb Chiral Symmetry Breaking | Musings
The chiral symmetry is spontaneously broken, and is realized nonlinearly on some Goldstone boson fields, whose Wess-Zumino term provides the anomalous variation satisfying the 't Hooft Anomaly Matching constraints.
I suppose that one might imagine some circumstances in which some mixture of 1 and 2 arose, with part of the chiral symmetry realized linearly on massless fermions, and part spontaneously-broken.
But, since QCD-like theories do not break their vector-like symmetries (by a theorem of Vafa and Witten), this mixed possibility does not arise.
golem.ph.utexas.edu /~distler/blog/archives/000970.html   (0 words)

 Excitation of Spirals and Chiral Symmetry Breaking in Rayleigh-Benard Convection -- Ecke et al. 269 (5231): 1704 -- ...
Excitation of Spirals and Chiral Symmetry Breaking in Rayleigh-Benard Convection -- Ecke et al.
Excitation of Spirals and Chiral Symmetry Breaking in Rayleigh-Bénard Convection
breaks the zero-rotation chiral symmetry between clockwise and
www.sciencemag.org /cgi/content/short/269/5231/1704   (0 words)

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