TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.20.2.032
TI  - Multichannel topological Kondo models and their low-temperature conductances
PY  - 2026/02/05
UR  - https://scipost.org/SciPostPhys.20.2.032
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 20
IS  - 2
SP  - 032
A1  - Li, Guangjie
AU  - König, Elio J.
AU  - Väyrynen, Jukka I.
AB  - In the multichannel Kondo effect, overscreening of a magnetic impurity by conduction electrons leads to a frustrated exotic ground state. It has been proposed that multichannel topological Kondo (MCTK) model involving topological Cooper pair boxes with $M$ Majorana modes [SO($M$) "spin"] and $N$ spinless electron channels exhibits an exotic intermediate coupling fixed point. This intermediate fixed point has been analyzed through large-$N$ perturbative calculations, which gives a zero-temperature conductance decaying as $1/N^2$ in the large-$N$ limit. However, the conductance at this intermediate fixed point has not been calculated for generic $N$. Using representation theory, we verify the existence of this intermediate-coupling fixed point and find the strong-coupling effective Hamiltonian for the case $M=4$. Using conformal field theory techniques for SO($M$), we generalize the notion of overscreening and conclude that the MCTK model is an overscreened Kondo model. We find the fixed-point finite-size energy spectrum and the leading irrelevant operator (LIO). We express the fixed-point conductance in terms of the modular S-matrix of SO($M$) for general $N$, confirming the previous large-$N$ result. We describe the finite-temperature corrections to the conductance by the LIO and find that they are qualitatively different for the cases $N=1$ and $N≥2$ due to the different fusion outcomes with the current operator. We also compare the multichannel topological Kondo model to the topological symplectic Kondo model.
ER  -

@Article{10.21468/SciPostPhys.20.2.032,
	title={{Multichannel topological Kondo models and their low-temperature conductances}},
	author={Guangjie Li and Elio J. König and Jukka I. Väyrynen},
	journal={SciPost Phys.},
	volume={20},
	pages={032},
	year={2026},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.20.2.032},
	url={https://scipost.org/10.21468/SciPostPhys.20.2.032},
}