Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

G-factor in BMT equation

  1. Nov 25, 2012 #1
    in Bargmann–Michel–Telegdi equation
    {\;\,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]\;,
    there is [itex]g[/itex]-factor present. I'm a bit confused about its definition. If it is defined as
    \boldsymbol{\mu}_S = \frac{g_{e,p}\mu_\mathrm{B}}{\hbar}\boldsymbol{S}\;,
    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?
  2. jcsd
  3. Nov 25, 2012 #2
    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.
  4. Nov 26, 2012 #3
    So in BMT g is the absolute value of g-factor?
  5. Nov 26, 2012 #4
    yes,it is always the absolute value.I hope it is same as the lande factor.However what is μB in your eqn.
  6. Nov 26, 2012 #5
    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.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook