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Physics Letters B

Exact open anisotropic XY Hamiltonian from a non-semisimple boundary completion

Ze Tao, Hao Yan, Fujun Liu

Published Sep 5, 2026• 0 citations
Publisher

Abstract

We solve the radical-square reflection residual of the symmetric elliptic free-fermion eight-vertex model in a minimal four-dimensional local coefficient algebra. Two parity-odd tangent channels generate an ordered product in the square of the radical, and the reflection equation fixes its parity-even completion within the trace-fixed sector whose radical-square term starts at order u 2 . The resulting regular boundary object enters a double-row transfer construction. Its scalar quotient yields the open anisotropic XY Hamiltonian with diagonal boundary fields, while the full transfer object retains the non-semisimple boundary channels. Finite-chain audits through N = 12 accompany the analytic construction.

DOI
10.1016/j.physletb.2026.140920

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