"Finite size effect"의 두 판 사이의 차이

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8번째 줄: 8번째 줄:
 
** topology of space
 
** topology of space
 
* the boundaries restrict the modes of the quantum fields 
 
* the boundaries restrict the modes of the quantum fields 
* give rise to measurable and important forces
+
* give rise to measurable and important forces<br>
* 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
 
  
 
 
 
 
17번째 줄: 14번째 줄:
 
<h5>how to compute the Casimir effect</h5>
 
<h5>how to compute the Casimir effect</h5>
  
* zero-point energy in the presenve of the boundaries
+
* zero-point energy in the presence of the boundaries<br>
*  
+
** 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<br>
 +
** 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<br>
 +
** represents the vacuum expectation value of the produc of fields
  
 
 
 
 
  
<h5>QFT interpretation of the Casimirt effect</h5>
+
<h5>QFT interpretation of the Casimir effect</h5>
  
 
*  
 
*  

2009년 8월 10일 (월) 02:26 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
  • \(z \to w=\frac{L}{2\pi}\ln z\)
  • 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

 

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