Generalized symmetries and deformations of symmetric product orbifolds

A bstract We construct generalized symmetries in two-dimensional symmetric product orbifold CFTs Sym N ( $$ \mathcal{T} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>T</mml:mi> </mml:math> ), for a generic seed CFT $$ \mathcal{T} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>T</mml:mi> </mml:math> . These symmetries are more general than the universal and maximally symmetric ones previously constructed. We show that, up to one fine-tuned example when the number of copies N equals four, the only symmetries that can be preserved under twisted sector marginal deformations are invertible and maximally symmetric. The results are obtained in two ways. First, using the mathematical machinery of G -equivariantization of fusion categories, and second, via the projector construction of topological defect lines. As an application, we classify all preserved symmetries in symmetric product orbifold CFTs with the seed CFT given by any A -series $$ \mathcal{N}=\left(2,2\right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>N</mml:mi> <mml:mo>=</mml:mo> <mml:mfenced> <mml:mn>2</mml:mn> <mml:mn>2</mml:mn> </mml:mfenced> </mml:math> minimal model. We comment on the implications of our results for holography.