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Autoequivalences and stability conditions on a degenerate K3 surface

2025/10/15 by H. ARAI, Arai, Hayato
Physics and Astronomy · Mathematics · #Quantum chaos and dynamical systems #Spectral Theory in Mathematical Physics

paper · pdf · doi:10.48550/arxiv.2510.13526

Abstract

We study autoequivalences and stability conditions on the derived category of coherent sheaves on a singular surface X which arises as an open subvariety of a type III Kulikov degeneration of K3 surfaces. The surface X consists of four irreducible components, one of which is ℙ2, and the others are non-compact rational surfaces. Using a comparison with the total space of the degeneration, we show that the connected component Stab^†(Db2(X)) of the space of stability conditions on the supported derived category Db2(X) containing geometric stability conditions is simply connected, and describe its wall-and-chamber structure via half-spherical twists. As consequences, we determine the subgroup of the autoequivalence group Aut(Db(X)) that preserves this component; it is isomorphic to ℤ × Γ1(3) × Aut(X), where Γ1(3) ⊂ SL(2,ℤ) is the congruence subgroup of level~3.

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