Anomalous magnetic moment of electron

수학노트
http://bomber0.myid.net/ (토론)님의 2011년 1월 17일 (월) 12:22 판
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introduction
  • amplitude = sum of integrals = \(\sum_{n\text{ loops}}\) sum of integrals
  • anomalous electron magnetic dipole moment 1.00115965219
  • 11 digits match
  • as n grows, number of Feynman diagrams grows exponentially
  • integrals are becoming difficult

 

 

classical magnetic moment
  • [1]http://www.wolframalpha.com/input/?i=fine+structure+constant
  • [2]http://www.wolframalpha.com/input/?i=1/fine+structure+constant
  • A classical electron moving around a nucleus in a circular orbit
    • 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
    • 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 \(\gamma = \mu/L=-e/2m_e\)

 

 

 

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\[\mathbf{\mu}=q\mathbf{S}/m\]

[/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.

 

 

 

 

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]
  • Toichiro Kinoshita

 

four-loop diagrams
  •  891 diagrams

 

 

five-loop Feynman diagrams

 

 

 

anaomalous muon magnetic dipole moment

 

 

memo

 

 

history

 

 

related items

 

 

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