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JOURNALS // Matematicheskie Trudy // Archive

Mat. Tr., 2025 Volume 28, Number 1, Pages 39–93 (Mi mt726)

Invariants of links and $3$-manifolds from the modular category with two simple objects

P. G. Korablevab

a N.N. Krasovskii Institute of Mathematics and Mechanics of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
b Chelyabinsk state university, Chelyabinsk, Russia

Abstract: In this paper we construct a modular category $\mathfrak{E}$ containing exactly two simple objects. Using a special technique, two invariants are extracted from it: a complex-valued invariant of Reshetikhin – Turaev type $rt_{\varepsilon}$ of unoriented links in the $3$-sphere and of $3$-manifolds, and a real-valued invariant of Turaev – Viro type $tv_{\varepsilon}$ of $3$-manifolds. The values of these two invariants of $3$-manifolds are related by the equality $|rt_{\varepsilon}|^2\cdot (\varepsilon + 2) = tv_{\varepsilon}$, where $\varepsilon$ is the root of the equation $\varepsilon^2 = \varepsilon + 1$. It is proved that the $tv_{\varepsilon}$ invariant exactly coincides with the $\varepsilon$-invariant of $3$-manifolds.

Key words: modular category, Reshetikhin – Turaev type invariant, Turaev – Viro type invariant, $\varepsilon$-invariant.

UDC: 515.16

Received: 21.05.2024
Revised: 10.01.2025
Accepted: 29.01.2025

DOI: 10.25205/1560-750X-2025-28-1-39-93



© Steklov Math. Inst. of RAS, 2026