How Does a Magnetic Field Influence Positronium States?

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SUMMARY

The discussion focuses on the influence of magnetic fields on the singlet and triplet states of positronium. The user attempts to model the interaction using the equation \(\vec{B} \cdot (\vec{M}_{1}+\vec{M}_{2})= \mu B(S_{1z}-S_{2z})\), noting that the magnetic moments of the positron and electron are opposite. However, the user finds that this interaction does not lead to energy level splitting in the first order of perturbation theory. The conclusion suggests that second-order perturbation theory may be necessary to observe any effects, emphasizing that spin is the primary factor in this analysis.

PREREQUISITES
  • Understanding of positronium states (singlet and triplet)
  • Familiarity with magnetic moment concepts
  • Knowledge of first and second-order perturbation theory
  • Basic principles of quantum mechanics, particularly spin
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  • Study second-order perturbation theory in quantum mechanics
  • Research the properties of positronium and its energy levels
  • Explore the effects of magnetic fields on quantum states
  • Learn about the role of spin in quantum systems
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Physicists, quantum mechanics students, and researchers interested in the behavior of positronium in magnetic fields.

"pi"mp
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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:

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

where the minus sign comes about thanks to what I mentioned above. However, when I write out the singlet and doublet states in the |s_{1}=s_{2}=\frac{1}{2} s_{1z}\, \, s_{2z} \rangle 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 :)
 
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Is the spin the only thing that matters?
 
Yes. We are neglecting any possible orbital angular momentum.
 

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