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Article Dans Une Revue Physical Review B Année : 2022

Fixed point annihilation for a spin in a fluctuating field

Résumé

A quantum spin impurity coupled to a gapless free field (the Bose-Kondo model) can be represented as a (0+1)-dimensional field theory with long-range-in-time interactions that decay as |tt|(2δ). This theory is a simpler analog of nonlinear σ models with topological Wess-Zumino-Witten terms in higher dimensions. In this Letter we show that the renormalization group (RG) flows for the impurity problem exhibit an annihilation between two nontrivial RG fixed points at a critical value δc of the interaction exponent. The calculation is controlled at large spin S. This clarifies the phase diagram of the Bose-Kondo model and shows that it serves as a toy model for phenomena involving fixed point annihilation and “quasiuniversality” in higher dimensions.

Dates et versions

hal-03594403 , version 1 (02-03-2022)

Identifiants

Citer

Adam Nahum. Fixed point annihilation for a spin in a fluctuating field. Physical Review B, 2022, 106 (8), pp.L081109. ⟨10.1103/PhysRevB.106.L081109⟩. ⟨hal-03594403⟩
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