Spin system and Pauli exclusion principle

수학노트
http://bomber0.myid.net/ (토론)님의 2010년 9월 22일 (수) 18:40 판
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introduction
  • the simplest example of quantum mechanical system
  • quantization of the angular momentum
  • measures as being some multiple of Planck's constant divided by 2pi

 

 

 

representation theory
  • concept from the representation of  \(SU(2)\)
  • half of highest weight is called the spin of the module
    • Casimir operator can also detect this number.
  • spin \(1/2\) is the most important case since they are the matter particles
  • this is why we have half-integral spin although those representation are integral highest weight representations.

 

 

operator formulation
  • 파울리 행렬 (해밀턴의 사원수 참조)
    \(\sigma_1 = \sigma_x = \begin{pmatrix} 0&1\\ 1&0 \end{pmatrix} \)
    \(\sigma_2 = \sigma_y = \begin{pmatrix} 0&-i\\ i&0 \end{pmatrix} \)
    \(\sigma_3 = \sigma_z = \begin{pmatrix} 1&0\\ 0&-1 \end{pmatrix}\)
  • raising and lowering 연산자
    \(\sigma_{\pm}=\frac{1}{2}(\sigma_{x}\pm i\sigma_{y})\)
    \(\sigma_{+}=\frac{1}{2}(\sigma_{x}+ i\sigma_{y})=\begin{pmatrix} 0&1\\ 0&0 \end{pmatrix}\)
    \(\sigma_{-}=\frac{1}{2}(\sigma_{x}- i\sigma_{y})=\begin{pmatrix} 0&0\\ 1&0 \end{pmatrix}\)
    \([\sigma_{z},\sigma_{\pm}]=\pm 2\sigma_{\pm}\)

 

 

sl(2)
  • 3차원 리대수
    \(E=\)
    \(F\)
    \(H=\begin{pmatrix} 1&0\ 0&-1 \end{pmatrix}\)
  • commutator
    \([E,F]=H\)
    \([H,E]=2E\)
    \([H,F]=-2F\)

 

 

spin particle statstics
  • Bosons
  • photon
  • vector boson
  • Gluon
  • follows Bose-Einstein statistics
  • force-transmitting particles
  •  

 

  • Fermions = spin- \(1/2\) particles
    • quarks and leptons
    • follows Fermi-Dirac statistics
    • matter particles
  •  

 

 

 

history

 

 

related items

 

 

encyclopedia

 

 

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expositions

 

 

 

articles

 

 

 

question and answers(Math Overflow)

 

 

blogs

 

 

experts on the field

 

 

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