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

Fine Structure of Positronium

  1. Jul 25, 2014 #1
    Hi all,
    I'm trying to compute the effect that a magnetic field has on the singlet and triplet states of positronium. I know that the positron has a charge and magnetic moment opposite that of the electron, so I'm tempted to write the interaction as:

    [tex] \vec{B} \cdot (\vec{M}_{1}+\vec{M}_{2})= \mu B(S_{1z}-S_{2z}) [/tex]

    where the minus sign comes about thanks to what I mentioned above. However, when I write out the singlet and doublet states in the [itex] |s_{1}=s_{2}=\frac{1}{2} s_{1z}\, \, s_{2z} \rangle [/itex] basis, I get that the above interaction does not split the energy levels...at least to first order.

    Did I do something wrong? If not, do I need to try 2nd order perturbation theory?
    Thanks :)
  2. jcsd
  3. Jul 25, 2014 #2

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2017 Award

    Is the spin the only thing that matters?
  4. Jul 25, 2014 #3
    Yes. We are neglecting any possible orbital angular momentum.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook