"Finite size effect"의 두 판 사이의 차이

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36번째 줄: 36번째 줄:
  
 
*   <br>
 
*   <br>
*  transformaion<br><math>z \to w=\frac{L}{2\pi}\ln z</math><br>
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* strip geometry
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*  transformaion<br><math>z \to w=\frac{L}{2\pi}\ln z</math><br> maps the entire plane onto a strip of width L<br>
 
*  Schwarzian derivative<br><math>\frac{1}{2z^2}</math><br>
 
*  Schwarzian derivative<br><math>\frac{1}{2z^2}</math><br>
 
*  energy momentum tensor changes<br><math>T_{cyl}(w)=(\frac{2\pi}{L})^2\{T_{pl}(z)z^2-\frac{c}{24}\}</math><br><math>L_0 \to L_0-c/24</math><br>
 
*  energy momentum tensor changes<br><math>T_{cyl}(w)=(\frac{2\pi}{L})^2\{T_{pl}(z)z^2-\frac{c}{24}\}</math><br><math>L_0 \to L_0-c/24</math><br>
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<h5 style="line-height: 3.428em; margin: 0px; color: rgb(34, 61, 103); font-family: 'malgun gothic',dotum,gulim,sans-serif; font-size: 1.166em; background-position: 0px 100%;">참고할만한 자료</h5>
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<h5 style="line-height: 3.428em; margin: 0px; color: rgb(34, 61, 103); font-family: 'malgun gothic',dotum,gulim,sans-serif; font-size: 1.166em; background-position: 0px 100%;">encyclopedia</h5>
  
 
* [http://ko.wikipedia.org/wiki/%EC%B9%B4%EC%8B%9C%EB%AF%B8%EB%A5%B4%ED%9A%A8%EA%B3%BC http://ko.wikipedia.org/wiki/카시미르효과]
 
* [http://ko.wikipedia.org/wiki/%EC%B9%B4%EC%8B%9C%EB%AF%B8%EB%A5%B4%ED%9A%A8%EA%B3%BC http://ko.wikipedia.org/wiki/카시미르효과]
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<h5>articles</h5>
 
<h5>articles</h5>
  
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* Conformal invariance, the central charge, and universal finite-size amplitudes at criticality H. W. J. Blöte, J. Cardy and M. P. Nightingale, Phys. Rev. Lett. 56, 742–745 (1986)
 
* [http://prl.aps.org/abstract/PRL/v56/i7/p742_1 Conformal invariance, the central charge, and universal finite-size amplitudes at criticality]
 
* [http://prl.aps.org/abstract/PRL/v56/i7/p742_1 Conformal invariance, the central charge, and universal finite-size amplitudes at criticality]
  

2010년 5월 25일 (화) 17:52 판

introduction
  • Casimir effect in QED is one example of finite size effect
  • the stress on the bounding surfaces when quantum field is confined to finite volume of space
  • type of boundaries
    • real material media
    • interface between two different phases of the vacuum of a field theory such as QCD, in which case colored field may only exist in the interior region
    • topology of space
  • the boundaries restrict the modes of the quantum fields 
  • give rise to measurable and important forces

 

how to compute the Casimir effect
  • zero-point energy in the presence of the boundaries
    • sum over all modes
    • any kind of constraint or boudary conditions on the the zero-point modes of the quantum fields in question, including backgrounds such as gravity
    • In a model without boundary conditions, the Hamiltonian value associated wih the vacuum or ground state, called zero-point energy, is usually discarded because, despite being infinite, may be reabsorbed in a suitable redefinition of the energy origin
    • there are several ways to put such an adjustment into practice, normal ordering being oneof the most popular
  • Green's functions method
    • represents the vacuum expectation value of the produc of fields
  •  

 

QFT interpretation of the Casimir effect
  •  

 

 

conformal transform from the plane to cylinder
  •  
  • strip geometry
  • transformaion
    \(z \to w=\frac{L}{2\pi}\ln z\)
    maps the entire plane onto a strip of width L
  • Schwarzian derivative
    \(\frac{1}{2z^2}\)
  • energy momentum tensor changes
    \(T_{cyl}(w)=(\frac{2\pi}{L})^2\{T_{pl}(z)z^2-\frac{c}{24}\}\)
    \(L_0 \to L_0-c/24\)
  • the central charge emerges
  • central charge is proportional to the Casimir energy, the change in the vacuum energy density brought about by the periodicity condition on the cylinder

 

 

vacuum energy density

\(<T_{cyl}(w)>=-\frac{c\pi^2}{6L^2}\)

 

 

free energy per unit length
  • formula
    \(F_L=f_{0}L-\frac{c\pi}{6L}\)
    where \(f_{0}\) is the free energy per unit area in the thermodynamic \(L\to\infty\) limit

 

 

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