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Particle-hole symmetric slave-boson method for the mixed valence problem

Liam L. H. Lau*

Piers Coleman

  • Center for Materials Theory, Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Rd., Piscataway, New Jersey 08854-8019, USA

  • Center for Materials Theory, Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Rd., Piscataway, New Jersey 08854-8019, USA and Hubbard Theory Consortium, Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom

  • *Contact author: liam.lh.lau@physics.rutgers.edu
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Phys. Rev. B 113, 045107 – Published 2 January, 2026

DOI: https://doi.org/10.1103/86gn-pfyl

Abstract

We introduce an analytic slave-boson method for treating the finite-U Anderson impurity model. Our approach introduces two bosons to track both Q⇌Q±1 valence fluctuations and reduces to a single symmetric s boson in the effective action, encoding all the high-energy atomic physics information in the boson's kinematics, while the low-energy part of the action remains unchanged across finite-U, infinite-U, and Kondo limits. We recover the infinite-U- and Kondo-limit actions from our approach and show that the Kondo resonance already develops in the normal state when the slave boson has yet to condense. We show that the slave rotor and s boson have the same algebraic structure, and we establish a unified functional integral framework connecting the s-boson and slave-rotor representations for the single-impurity Anderson model.

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Phys. Rev. B 113, 045107– Published 2 January, 2026
  • Received 17 September 2025
  • Revised 9 December 2025
  • Accepted 15 December 2025
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