Perturbation solution and the Dirac equation

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SUMMARY

The discussion focuses on solving the Dirac equation with a small gauge potential using perturbation theory. The equation is expressed as $$(\gamma^\mu\partial_\mu-m+\epsilon\gamma^\mu A_\mu(x))\psi(x) = 0$$, where the first-order solution is provided. The integral solution involves evaluating the expression $$\psi(x) = \psi_0(x) +\tau\int\frac{d^4p}{(2\pi)^4}\int d^4x'\frac{e^{-ip(x-x')}}{\gamma_\mu{p}^\mu-m} \gamma^\mu A_\mu(x')\psi_0(x')+\mathcal{O}(\tau^2)$$. The discussion also raises questions about solving the integral for a constant gauge potential $$A(x)= Ee_x$$ and determining the form of $$\psi_0(x)$$.

PREREQUISITES
  • Understanding of the Dirac equation and its significance in quantum mechanics.
  • Familiarity with perturbation theory in quantum field theory.
  • Knowledge of gauge potentials and their role in quantum mechanics.
  • Proficiency in evaluating multi-dimensional integrals in theoretical physics.
NEXT STEPS
  • Study the application of perturbation theory to the Dirac equation in detail.
  • Learn about the evaluation of integrals involving gamma matrices and momentum space.
  • Investigate the implications of constant gauge potentials on quantum states.
  • Explore advanced topics in quantum field theory related to gauge invariance and symmetries.
USEFUL FOR

The discussion is beneficial for theoretical physicists, particularly those specializing in quantum mechanics and quantum field theory, as well as graduate students seeking to deepen their understanding of the Dirac equation and perturbation methods.

Neutrinos02
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I'd like to know how to solve the dirac equation with some small gauge potential $\epsilon \gamma^\mu{A}_\mu(x)$ by applying perturbation theory. The equations reads as $$(\gamma^\mu\partial_\mu-m+\epsilon\gamma^\mu A_\mu(x))\psi(x) = 0.$$

The solution up to first order is

$$ \psi(x) = \psi_0(x) +\tau\int\frac{d^4p}{(2\pi)^4}\int d^4x'\frac{e^{-ip(x-x')}}{\gamma_\mu{p}^\mu-m} \gamma^\mu A_\mu(x')\psi_0(x')+\mathcal{O}(\tau^2).$$

Is there any possibility to solve this integral for an constant $$A(x)= Ee_x$$?
 
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How you figured out what ##\psi_0(x)## is? If so, what happens when you plug it into the integral?

In fact, in present form you should already be able to perform the $$p$$ integral - have you tried to do so?
 

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