"Gauge theory"의 두 판 사이의 차이

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==introduction==
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* {{수학노트|url=게이지_이론}}
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==meaning of the gague invariance==
 
==meaning of the gague invariance==
  
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*  one example is the electromagnetic field<br>
 
*  one example is the electromagnetic field<br>
 
 
 
 
 
 
 
==Gauge invariance of the QED Lagrangian==
 
 
<math>\mathcal{L} =  \bar{\psi} (i\gamma^\mu \partial_\mu -m)\psi - \frac{1}{4}F_{\mu\nu}F^{\mu\nu} -e\bar{\psi}\gamma^\mu \psi A_\mu</math>
 
 
Now we have a Lagrangian with interaction terms.
 
 
*  local phase transformation of fields<br><math>\psi(x) \to  e^{i\alpha(x)}\psi(x)</math><br>
 
*  gauge transformation of electromagnetic field<br><math>A_{\mu}(x) \to A_{\mu}(x)+\frac{1}{e}\partial_{\mu}\alpha(x)</math><br>
 
*  Look at the [[QED]] page<br>
 
* {{수학노트|url=게이지_이론}}
 
  
 
 
 
 

2013년 3월 23일 (토) 05:04 판

introduction


meaning of the gague invariance

  • gauge = measure
  • gauge invariance = measurement에 있어서의 invariance를 말함
  • Lagrangian should be gauge invariant.

   

gauge field

  • a gauge field is defined as a four-vector field with the freedom of gauge transformation, and it corresponds to massless particlas of spin one
  • one example is the electromagnetic field

 

gauge field tensor

  • electromagnetic field tensor  \(F_{\mu\nu} = \partial_\mu A_\nu - \partial_\nu A_\mu \,\!\)
  • general gauge fields tensor  \(G_{\mu\nu}^{a}=\partial_{\mu}W_{\nu}^{a}-\partial_{\nu}W_{\mu}^{a}-gw^{abc}W_{\mu}^{b}W_{\nu}^{c}\)

 

 

examples of renormalizable gauge theory

 

 

Abelian gauge theory

  • abelian gauge theory has a duality

 

 

Non-Abelian gauge theory

 

 

differential geometry formulation

  • manifold \(\mathbb R^{1,3}\) and having a vector bundle gives a connection
  • connection \(A\) = special kind of 1-form 
  • \(dA\) = 2-form which measures the electromagnetic charge
  • Then the Chern class measures the magnetic charge.

 

 

Principal G-bundle

 

 

 

3d Chern-Simons theory

  • 3d Chern-Simons theory on \(\Sigma\times \mathbb R^{1}\) with gauge choice \(A_0=0\) is the moduli space of flat connections on \(\Sigma\).
  • analogy with class field theory
  • replace \(\Sigma\) by \(spec O_K\)
  • then flat connection on \(spec O_K\) is given by Homomorphism group the absolute Galois group Gal(\barQ/K)->U(1)
  • Now from An's article, 

 

 

메모

 

 

related items

 

 

encyclopedia

 

 

books

  • The Geometry of Physics: An Introduction
  • An elementary primer for gauge theory
  • 찾아볼 수학책

 

 

expositions

 

 

articles