Dilation (metric space): Difference between revisions
en>Schmloof m WikiCleaner 0.99 - Repairing link to disambiguation page - You can help! |
en>NottNott m Reverted 1 edit by 142.167.148.200 (talk) to last revision by 132.64.32.85. (TW) |
||
Line 1: | Line 1: | ||
== | {{Distinguish|Wess–Zumino model}} | ||
In [[theoretical physics]] and [[mathematics]], the '''Wess–Zumino–Witten (WZW) model''', also called the '''Wess–Zumino–Novikov–Witten model''', is a simple model of [[conformal field theory]] whose solutions are realized by [[affine Kac–Moody algebra]]s. It is named after [[Julius Wess]], [[Bruno Zumino]], [[Sergei Novikov (mathematician)|Sergei Novikov]] and [[Edward Witten]]. | |||
<ref>{{cite doi|10.1016/0370-2693(71)90582-X |noedit }}</ref> | |||
<ref>{{cite doi| 10.1016/0550-3213(83)90063-9|noedit }}</ref> | |||
<ref>{{cite doi|10.1007/BF01215276|noedit}} </ref> | |||
<ref>{{cite journal | | |||
author=Novikov, S.P. | title=Multivalued functions and functionals. An analogue of the Morse theory | | |||
journal= Sov. Math., Dokl. | | |||
volume=24 | | |||
pages=222–226 | | |||
year=1981}}; {{cite doi|10.1070/RM1982v037n05ABEH004020|noedit}}</ref> | |||
==Action== | |||
Let ''G'' denote a [[compact space|compact]] [[simply-connected]] [[Lie group]] and ''g'' its [[simple Lie algebra]]. Suppose that ''γ'' is a ''G''-valued field on the [[complex plane]]. More precisely, we want ''γ'' to be defined on the [[Riemann sphere]] '''''S''''' ², which amounts to the complex plane [[Compactification (mathematics)|compactified]] by adding a [[point at infinity]]. | |||
The WZW model is then a [[nonlinear sigma model]] defined by ''γ'' with an [[action (physics)|action]] given by | |||
:<math>S_k(\gamma)= - \, \frac {k}{8\pi} \int_{S^2} d^2x\, | |||
\mathcal{K} (\gamma^{-1} \partial^\mu \gamma \, , \, | |||
\gamma^{-1} \partial_\mu \gamma) + 2\pi k\, S^{\mathrm WZ}(\gamma).</math> | |||
= | Here, {{math|∂<sub>''μ''</sub> {{=}} ∂/∂''x''<sup>''μ''</sup>}} is the [[partial derivative]] and the usual [[summation convention]] over indices is used, with a [[Euclidean metric]]. Here, <math>\mathcal{K}</math> is the [[Killing form]] on ''g'', and thus the first term is the standard kinetic term of [[quantum field theory]]. | ||
The term ''S''<sup>WZ</sup> is called the ''Wess–Zumino term'' and can be written as | |||
:<math>S^{\mathrm WZ}(\gamma) = - \, \frac{1}{48\pi^2} \int_{B^3} d^3y\, | |||
\epsilon^{ijk} \mathcal{K} \left( | |||
\gamma^{-1} \, \frac {\partial \gamma} {\partial y^i} \, , \, | |||
\left[ | |||
\gamma^{-1} \, \frac {\partial \gamma} {\partial y^j} \, , \, | |||
\gamma^{-1} \, \frac {\partial \gamma} {\partial y^k} | |||
\right] | |||
\right)</math> | |||
== | where [,] is the [[commutator]], {{math|''ε<sup>ijk</sup>''}} is the [[completely anti-symmetric tensor]], and the integration coordinates ''y''<sup>''i''</sup> for ''i''=1,2,3 range over the [[unit ball]] '''''B''''' ³. In this integral, the field γ has been extended so that it is defined on the interior of the unit ball. This extension can always be done because the [[homotopy group]] π<sub>2</sub> (''G'') always vanishes for any compact, simply-connected Lie group, and we originally defined ''γ'' on the 2-sphere '''''S''''' ² = ∂'''''B''''' ³. | ||
===Pullback=== | |||
Note that if ''e''<sub>''a''</sub> are the basis vectors for the [[Lie algebra]], then <math>\mathcal{K} (e_a, [e_b, e_c])</math> are the [[structure constants]] of the Lie algebra. Note also that the structure constants are completely anti-symmetric, and thus they define a [[alternating form|3-form]] on the [[group manifold]] of ''G''. Thus, the integrand above is just the [[pullback (differential geometry)|pullback]] of the harmonic 3-form to the ball '''''B''''' ³. Denoting the harmonic 3-form by ''c'' and the pullback by ''γ''<sup>*</sup>, one then has | |||
:<math>S^{\mathrm WZ}(\gamma) = \int_{B^3} \gamma^{*} c.</math> | |||
This form leads directly to a topological analysis of the WZ term. | |||
Geometrically, this term describes the [[Torsion tensor|torsion]] of the respective manifold.<ref>{{cite doi| 10.1016/0550-3213(85)90053-7|noedit}}</ref> The presence of this torsion compels [[teleparallelism]] of the manifold, and thus trivialization of the torsionful [[Affine connection|curvature tensor]]; and hence arrest of the renormalization flow, an [[infrared fixed point]] of the [[renormalization group]], a phenomenon termed '''geometrostasis'''. | |||
===Topological obstructions=== | |||
The extension of the field to the interior of the ball is not unique; the need that the physics be independent of the extension imposes a quanitization condition on the coupling constant ''k''. Consider two different extensions of γ to the interior of the ball. They are maps from flat 3-space into the Lie group ''G''. Consider now glueing these two balls together at their boundary '''''S'''''². The result of the gluing is a topological 3-sphere; each ball '''''B'''''³ is a hemisphere of '''''S'''''³. The two different extensions of ''γ'' on each ball now becomes a map '''''S'''''³ → ''G''. However, the homotopy group π<sub>3</sub>(''G'') = ℤ for any compact, connected simple Lie group ''G''. | |||
= | Thus, one has | ||
:<math>S^{\mathrm WZ}(\gamma) = S^{\mathrm WZ}(\gamma')+n ~,</math> | |||
where ''γ'' and ''γ' '' denote the two different extensions onto the ball, and ''n'', an integer, is the [[winding number]] of the glued-together map. The physics that this model leads to will stay the same if | |||
:<math>\exp \left(i2\pi k S^{\mathrm WZ}(\gamma) \right)= \exp \left( i2\pi k S^{\mathrm WZ}(\gamma')\right).</math> | |||
Thus, topological considerations lead one to conclude that coupling constant ''k'' must be an integer when ''G'' is a connected, compact, simple Lie group. For a semisimple or disconnected compact Lie group the level consists of an integer for each connected, simple component. | |||
This topological obstruction can also be seen in the representation theory of the [[affine Lie algebra]] symmetry of the theory. When each level is a positive integer the affine Lie algebra has unitary highest weight [[representation theory|representations]] with highest [[weight (representation theory)|weight]]s that are dominant integral. Such representations are easier to work with as they decompose into finite-dimensional subalgebras with respect to the subalgebras spanned by each [[Simple root (root system)|simple root]], the corresponding negative root and their commutator, which is a [[Cartan matrix|Cartan generator]]. | |||
Often one is interested in a WZW model with a noncompact simple Lie group ''G'', such as [[SL2(R)|SL(2,ℝ)]] which has been used by [[Juan Maldacena]] and [[Hirosi Ooguri]] to describe [[string theory]] on a three-dimensional [[anti de Sitter space]],<ref>{{cite doi| 10.1063/1.1377273 |noedit}}</ref> which is the [[universal cover]] of the group SL(2,ℝ). In this case, as π<sub>3</sub>(SL(2, ℝ)) = 0, there is no topological obstruction and the level need not be integral. Correspondingly, the representation theory of such noncompact Lie groups is much richer than that of their compact counterparts. | |||
===Generalizations=== | |||
Although in the above, the WZW model is defined on the [[Riemann sphere]], it can be generalized so that the field γ lives on a compact [[Riemann surface]]. | |||
==Current algebra== | |||
The [[current algebra]] of the WZW model is a [[Kac–Moody algebra]]. The stress energy tensor is given by the [[Sugawara theory|Sugawara construction]]. | |||
===Coset Construction=== | |||
Taking the quotient of two WZW models gives a new conformal field theory whose central charge is the difference of the two original ones. | |||
==References== | |||
{{reflist}} | |||
{{Quantum field theories}} | |||
{{DEFAULTSORT:Wess-Zumino-Witten model}} | |||
[[Category:Lie groups]] | |||
[[Category:Quantum field theory]] | |||
[[Category:Conformal field theory]] | |||
[[Category:Exactly solvable models]] | |||
[[Category:Mathematical physics]] | |||
[[Category:Theoretical physics]] |
Revision as of 17:33, 17 June 2013
Template:Distinguish In theoretical physics and mathematics, the Wess–Zumino–Witten (WZW) model, also called the Wess–Zumino–Novikov–Witten model, is a simple model of conformal field theory whose solutions are realized by affine Kac–Moody algebras. It is named after Julius Wess, Bruno Zumino, Sergei Novikov and Edward Witten. [1] [2] [3] [4]
Action
Let G denote a compact simply-connected Lie group and g its simple Lie algebra. Suppose that γ is a G-valued field on the complex plane. More precisely, we want γ to be defined on the Riemann sphere S ², which amounts to the complex plane compactified by adding a point at infinity.
The WZW model is then a nonlinear sigma model defined by γ with an action given by
Here, Buying, selling and renting HDB and personal residential properties in Singapore are simple and transparent transactions. Although you are not required to engage a real property salesperson (generally often known as a "public listed property developers In singapore agent") to complete these property transactions, chances are you'll think about partaking one if you are not accustomed to the processes concerned.
Professional agents are readily available once you need to discover an condominium for hire in singapore In some cases, landlords will take into account you more favourably in case your agent comes to them than for those who tried to method them by yourself. You need to be careful, nevertheless, as you resolve in your agent. Ensure that the agent you are contemplating working with is registered with the IEA – Institute of Estate Brokers. Whereas it might sound a hassle to you, will probably be worth it in the end. The IEA works by an ordinary algorithm and regulations, so you'll protect yourself in opposition to probably going with a rogue agent who prices you more than they should for his or her service in finding you an residence for lease in singapore.
There isn't any deal too small. Property agents who are keen to find time for any deal even if the commission is small are the ones you want on your aspect. Additionally they present humbleness and might relate with the typical Singaporean higher. Relentlessly pursuing any deal, calling prospects even without being prompted. Even if they get rejected a hundred times, they still come again for more. These are the property brokers who will find consumers what they need eventually, and who would be the most successful in what they do. 4. Honesty and Integrity
This feature is suitable for you who need to get the tax deductions out of your PIC scheme to your property agency firm. It's endorsed that you visit the correct site for filling this tax return software. This utility must be submitted at the very least yearly to report your whole tax and tax return that you're going to receive in the current accounting 12 months. There may be an official website for this tax filling procedure. Filling this tax return software shouldn't be a tough thing to do for all business homeowners in Singapore.
A wholly owned subsidiary of SLP Worldwide, SLP Realty houses 900 associates to service SLP's fast rising portfolio of residential tasks. Real estate is a human-centric trade. Apart from offering comprehensive coaching applications for our associates, SLP Realty puts equal emphasis on creating human capabilities and creating sturdy teamwork throughout all ranges of our organisational hierarchy. Worldwide Presence At SLP International, our staff of execs is pushed to make sure our shoppers meet their enterprise and investment targets. Under is an inventory of some notable shoppers from completely different industries and markets, who've entrusted their real estate must the expertise of SLP Worldwide.
If you're looking for a real estate or Singapore property agent online, you merely need to belief your instinct. It is because you don't know which agent is sweet and which agent will not be. Carry out research on a number of brokers by looking out the internet. As soon as if you find yourself certain that a selected agent is dependable and trustworthy, you'll be able to choose to utilize his partnerise find you a house in Singapore. More often than not, a property agent is considered to be good if she or he places the contact data on his web site. This is able to imply that the agent does not thoughts you calling them and asking them any questions regarding properties in Singapore. After chatting with them you too can see them of their office after taking an appointment.
Another method by way of which you could find out whether the agent is sweet is by checking the feedback, of the shoppers, on the website. There are various individuals would publish their comments on the web site of the Singapore property agent. You can take a look at these feedback and the see whether it will be clever to hire that specific Singapore property agent. You may even get in contact with the developer immediately. Many Singapore property brokers know the developers and you may confirm the goodwill of the agent by asking the developer. is the partial derivative and the usual summation convention over indices is used, with a Euclidean metric. Here, is the Killing form on g, and thus the first term is the standard kinetic term of quantum field theory.
The term SWZ is called the Wess–Zumino term and can be written as
where [,] is the commutator, Buying, selling and renting HDB and personal residential properties in Singapore are simple and transparent transactions. Although you are not required to engage a real property salesperson (generally often known as a "public listed property developers In singapore agent") to complete these property transactions, chances are you'll think about partaking one if you are not accustomed to the processes concerned.
Professional agents are readily available once you need to discover an condominium for hire in singapore In some cases, landlords will take into account you more favourably in case your agent comes to them than for those who tried to method them by yourself. You need to be careful, nevertheless, as you resolve in your agent. Ensure that the agent you are contemplating working with is registered with the IEA – Institute of Estate Brokers. Whereas it might sound a hassle to you, will probably be worth it in the end. The IEA works by an ordinary algorithm and regulations, so you'll protect yourself in opposition to probably going with a rogue agent who prices you more than they should for his or her service in finding you an residence for lease in singapore.
There isn't any deal too small. Property agents who are keen to find time for any deal even if the commission is small are the ones you want on your aspect. Additionally they present humbleness and might relate with the typical Singaporean higher. Relentlessly pursuing any deal, calling prospects even without being prompted. Even if they get rejected a hundred times, they still come again for more. These are the property brokers who will find consumers what they need eventually, and who would be the most successful in what they do. 4. Honesty and Integrity
This feature is suitable for you who need to get the tax deductions out of your PIC scheme to your property agency firm. It's endorsed that you visit the correct site for filling this tax return software. This utility must be submitted at the very least yearly to report your whole tax and tax return that you're going to receive in the current accounting 12 months. There may be an official website for this tax filling procedure. Filling this tax return software shouldn't be a tough thing to do for all business homeowners in Singapore.
A wholly owned subsidiary of SLP Worldwide, SLP Realty houses 900 associates to service SLP's fast rising portfolio of residential tasks. Real estate is a human-centric trade. Apart from offering comprehensive coaching applications for our associates, SLP Realty puts equal emphasis on creating human capabilities and creating sturdy teamwork throughout all ranges of our organisational hierarchy. Worldwide Presence At SLP International, our staff of execs is pushed to make sure our shoppers meet their enterprise and investment targets. Under is an inventory of some notable shoppers from completely different industries and markets, who've entrusted their real estate must the expertise of SLP Worldwide.
If you're looking for a real estate or Singapore property agent online, you merely need to belief your instinct. It is because you don't know which agent is sweet and which agent will not be. Carry out research on a number of brokers by looking out the internet. As soon as if you find yourself certain that a selected agent is dependable and trustworthy, you'll be able to choose to utilize his partnerise find you a house in Singapore. More often than not, a property agent is considered to be good if she or he places the contact data on his web site. This is able to imply that the agent does not thoughts you calling them and asking them any questions regarding properties in Singapore. After chatting with them you too can see them of their office after taking an appointment.
Another method by way of which you could find out whether the agent is sweet is by checking the feedback, of the shoppers, on the website. There are various individuals would publish their comments on the web site of the Singapore property agent. You can take a look at these feedback and the see whether it will be clever to hire that specific Singapore property agent. You may even get in contact with the developer immediately. Many Singapore property brokers know the developers and you may confirm the goodwill of the agent by asking the developer. is the completely anti-symmetric tensor, and the integration coordinates yi for i=1,2,3 range over the unit ball B ³. In this integral, the field γ has been extended so that it is defined on the interior of the unit ball. This extension can always be done because the homotopy group π2 (G) always vanishes for any compact, simply-connected Lie group, and we originally defined γ on the 2-sphere S ² = ∂B ³.
Pullback
Note that if ea are the basis vectors for the Lie algebra, then are the structure constants of the Lie algebra. Note also that the structure constants are completely anti-symmetric, and thus they define a 3-form on the group manifold of G. Thus, the integrand above is just the pullback of the harmonic 3-form to the ball B ³. Denoting the harmonic 3-form by c and the pullback by γ*, one then has
This form leads directly to a topological analysis of the WZ term.
Geometrically, this term describes the torsion of the respective manifold.[5] The presence of this torsion compels teleparallelism of the manifold, and thus trivialization of the torsionful curvature tensor; and hence arrest of the renormalization flow, an infrared fixed point of the renormalization group, a phenomenon termed geometrostasis.
Topological obstructions
The extension of the field to the interior of the ball is not unique; the need that the physics be independent of the extension imposes a quanitization condition on the coupling constant k. Consider two different extensions of γ to the interior of the ball. They are maps from flat 3-space into the Lie group G. Consider now glueing these two balls together at their boundary S². The result of the gluing is a topological 3-sphere; each ball B³ is a hemisphere of S³. The two different extensions of γ on each ball now becomes a map S³ → G. However, the homotopy group π3(G) = ℤ for any compact, connected simple Lie group G.
Thus, one has
where γ and γ' denote the two different extensions onto the ball, and n, an integer, is the winding number of the glued-together map. The physics that this model leads to will stay the same if
Thus, topological considerations lead one to conclude that coupling constant k must be an integer when G is a connected, compact, simple Lie group. For a semisimple or disconnected compact Lie group the level consists of an integer for each connected, simple component.
This topological obstruction can also be seen in the representation theory of the affine Lie algebra symmetry of the theory. When each level is a positive integer the affine Lie algebra has unitary highest weight representations with highest weights that are dominant integral. Such representations are easier to work with as they decompose into finite-dimensional subalgebras with respect to the subalgebras spanned by each simple root, the corresponding negative root and their commutator, which is a Cartan generator.
Often one is interested in a WZW model with a noncompact simple Lie group G, such as SL(2,ℝ) which has been used by Juan Maldacena and Hirosi Ooguri to describe string theory on a three-dimensional anti de Sitter space,[6] which is the universal cover of the group SL(2,ℝ). In this case, as π3(SL(2, ℝ)) = 0, there is no topological obstruction and the level need not be integral. Correspondingly, the representation theory of such noncompact Lie groups is much richer than that of their compact counterparts.
Generalizations
Although in the above, the WZW model is defined on the Riemann sphere, it can be generalized so that the field γ lives on a compact Riemann surface.
Current algebra
The current algebra of the WZW model is a Kac–Moody algebra. The stress energy tensor is given by the Sugawara construction.
Coset Construction
Taking the quotient of two WZW models gives a new conformal field theory whose central charge is the difference of the two original ones.
References
43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.
Template:Quantum field theories
- ↑ Template:Cite doi
- ↑ Template:Cite doi
- ↑ Template:Cite doi
- ↑ One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting
In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang
Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules
Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.
A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running
The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang; Template:Cite doi - ↑ Template:Cite doi
- ↑ Template:Cite doi