Non-Perturbative Approach to Nearly Antiferromagnetic Fermi Liquids
نویسنده
چکیده
We present a non-perturbative approach to the problem of quasiparticles coupled to spin-fluctuations. If the fully dressed spin-fluctuation propagator is used in the Feynman graph expansion of the single particle Green’s function, the problem of summing all spin-fluctuation exchange Feynman graphs (i.e all the graphs without fermion loops) can be cast as a functional integral over Gaussian distributed random vector fields. The quasiparticle propagator is then obtained as the average over all field configurations of the non-interacting electron Green’s function in an external field. A Monte Carlo sampling of this functional integral does not suffer from the ”fermion sign problem” and offers an attractive alternative to perturbative calculations. We compare the results of our computer simulations to perturbation theory and self-consistent Eliashberg calculations.
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