"Anomalous magnetic moment of electron"의 두 판 사이의 차이

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13번째 줄: 13번째 줄:
 
<h5>classical magnetic moment</h5>
 
<h5>classical magnetic moment</h5>
  
* copied from [[spin system and Pauli exclusion principle|spin system]]
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* read [[spin system and Pauli exclusion principle|spin system]] first
*  A classical electron moving around a nucleus in a circular orbit<br>
 
** orbital angular momentum, L=m_evr
 
** magnetic dipole moment, \mu= -evr/2
 
** where e, m_e, v, and r are the electron´s charge, mass, velocity, and radius, respectively.
 
*  A classical electron of homogeneous mass and charge density rotating about a symmetry axis<br>
 
** angular momentum, L=(3/5)m_eR^2\Omega
 
** magnetic dipole moment, \mu= -(3/10)eR^2\Omega, where R and \Omega are the electron´s classical radius and rotating frequency
 
 
*  gyromagnetic ratio <math>\gamma = \mu/L=-e/2m_e</math><br>[/pages/7141159/attachments/4562863 I15-62-g20.jpg]<br>
 
*  gyromagnetic ratio <math>\gamma = \mu/L=-e/2m_e</math><br>[/pages/7141159/attachments/4562863 I15-62-g20.jpg]<br>
 
* pictures from [http://universe-review.ca/R15-12-QFT.htm#g2 Gyromagnetic Ratio and Anomalous Magnetic Moment]
 
* pictures from [http://universe-review.ca/R15-12-QFT.htm#g2 Gyromagnetic Ratio and Anomalous Magnetic Moment]
54번째 줄: 47번째 줄:
 
<h5 style="margin: 0px; line-height: 2em;">one-loop contribtion</h5>
 
<h5 style="margin: 0px; line-height: 2em;">one-loop contribtion</h5>
  
 
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 <br>
 
 
 
 
  
 
 
 
 
74번째 줄: 65번째 줄:
 
* 72 three-loop diagrams
 
* 72 three-loop diagrams
 
* [/pages/3589069/attachments/4562671 200432915395_150.gif]
 
* [/pages/3589069/attachments/4562671 200432915395_150.gif]
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*  Kinoshita, Toichiro. 1995. New Value of the alpha^{3} Electron Anomalous Magnetic Moment. Physical Review Letters 75, no. 26 (December 25): 4728. doi:[http://dx.doi.org/10.1103/PhysRevLett.75.4728 10.1103/PhysRevLett.75.4728]. <br>  <br>
  
* Toichiro Kinoshita
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2011년 1월 17일 (월) 12:44 판

introduction
  • amplitude = sum of integrals = \(\sum_{n\text{ loops}}\) sum of integrals
  • anomalous electron magnetic dipole moment 1.00115965219
  • theoretical computation matches 11 digits with experiments
  • as n grows, number of Feynman diagrams grows exponentially
  • integrals are becoming difficult

 

 

classical magnetic moment

 

 

anamalous electron magnetic dipole moment
  • In Dirac’s theory a point like spin 1/2 object of electric charge q and mass m has a magnetic moment\[\mathbf{\mu}=q\mathbf{S}/m\]
  • classical vs quantum
    [/pages/3589069/attachments/4562673 2004329152457_150.gif]

 

  • The g factor sets the strength of an electron’s interaction with a magnetic field.
  • In classical physics (left) magnetic lines of force (perpendicular to the page) induce a curvature in the electron’s path.
  • In quantum electrodynamics (right) the electron interacts with the field by emitting or absorbing a photon.
  • The event is represented in a Feynman diagram, where space extends along the horizontal axis and time moves up the vertical axis.
  • \(g=2(1+c_1\frac{\alpha}{2\pi}+c_2(\frac{\alpha}{2\pi})^2+c_3(\frac{\alpha}{2\pi})^3+\cdots)\)
  • http://www.wolframalpha.com/input/?i=fine+structure+constant
  • http://www.wolframalpha.com/input/?i=1/fine+structure+constant

 

 

 

one-loop contribtion
  •  

 

 

two-loop diagrams
  • 7 two-loop diagrams
    [/pages/3589069/attachments/4562669 2004329153354_150.gif]
    [/pages/7141159/attachments/4562733 I15-62-g2c.jpg]

 

 

three-loop diagrams
  • 72 three-loop diagrams
  • [/pages/3589069/attachments/4562671 200432915395_150.gif]
  • Kinoshita, Toichiro. 1995. New Value of the alpha^{3} Electron Anomalous Magnetic Moment. Physical Review Letters 75, no. 26 (December 25): 4728. doi:10.1103/PhysRevLett.75.4728
     

 

 

four-loop diagrams
  •  891 diagrams

 

 

five-loop Feynman diagrams

 

 

 

anaomalous muon magnetic dipole moment

 

 

memo

 

 

history

 

 

related items

 

 

encyclopedia

 

 

books

 

 

 

expositions

 

 

articles

 

 

 

question and answers(Math Overflow)

 

 

blogs

 

 

experts on the field

 

 

links