Non-invertible symmetries in SN orbifold CFTs and holography

A bstract We study non-invertible defects in two-dimensional S N orbifold CFTs. We construct universal defects which do not depend on the details of the seed CFT and hence exist in any orbifold CFT. Additionally, we investigate non-universal defects arising from the topological defects of the seed CFT. We argue that there exist universal defects that are non-trivial in the large- N limit, making them relevant for the AdS 3 /CFT 2 correspondence. We then focus on AdS 3 ×S 3 × $$ {\mathcal{M}}_4 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>M</mml:mi> <mml:mn>4</mml:mn> </mml:msub> </mml:math> with one unit of NS-NS flux and propose an explicit realization of these defects on the worldsheet.