What is the g-factor in the BMT equation?

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Discussion Overview

The discussion revolves around the g-factor in the Bargmann–Michel–Telegdi (BMT) equation, focusing on its definition and application in the context of particles such as electrons and protons. Participants explore the implications of using the g-factor's absolute value versus its signed value in calculations.

Discussion Character

  • Technical explanation, Debate/contested

Main Points Raised

  • One participant questions whether the g-factor should be used as a negative value in the BMT equation for electrons and protons, referencing specific values for g_e and g_p.
  • Another participant asserts that the magnetic moment (μ) is always in the opposite direction to spin for electrons and in the same direction for protons, suggesting that the magnitude of g should be used in calculations.
  • A participant seeks clarification on whether the g-factor in the BMT equation is indeed the absolute value.
  • One participant confirms that it is always the absolute value and relates it to the Lande factor, while asking for clarification on the term μ_B in the equation.
  • A later reply specifies that in their context, μ_B refers to the nuclear magneton, indicating a focus on protons in their discussion.

Areas of Agreement / Disagreement

Participants express differing views on whether the g-factor should be treated as a signed value or an absolute value, indicating a lack of consensus on this aspect of the discussion.

Contextual Notes

Participants reference specific values for g-factors and magnetic moments, but there is no resolution on the implications of using signed versus absolute values in the BMT equation.

pomaranca
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in Bargmann–Michel–Telegdi equation
[tex] {\;\,dS^\alpha\over d\tau}={e\over m}\bigg[{g\over2}F^{\alpha\beta}S_\beta+\left({g\over2}-1\right)U^\alpha\left(S_\lambda F^{\lambda\mu}U_\mu\right)\bigg]\;,[/tex]
there is [itex]g[/itex]-factor present. I'm a bit confused about its definition. If it is defined as
[tex] \boldsymbol{\mu}_S = \frac{g_{e,p}\mu_\mathrm{B}}{\hbar}\boldsymbol{S}\;,[/tex]
where for electron it is [itex]g_e=−2.0023193043622[/itex] and for proton [itex]g_p= 5.585694713[/itex], then in BMT equation one should probably use its negative [itex]g=-g_{e,p}[/itex] and not the absolute value.
Is this correct?
 
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μ is always in opposite direction to spin for electron and in same direction for proton.one always use the magnitude of g while dealing with it.
 
So in BMT g is the absolute value of g-factor?
 
yes,it is always the absolute value.I hope it is same as the lande factor.However what is μB in your eqn.
 
In my case [itex]\mu_B[/itex] is nuclear magneton [itex]\mu_N={e\hbar\over2m_P}[/itex] as I'm dealing with a proton. Thanks for your answer.
 

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