Surface defects on lens space and transfer matrices
Abstract
We study surface defects in four-dimensional ๐ฉ=2 theories of class ๐ฎ and ๐ฉ=1 theories of class ๐ฎk placed on L(r,1)ร S1. The lens space index depends on the fugacities p and q, and the effect of the defects on it is captured by difference operators acting on the fugacities and holonomies of flavor symmetries. For theories of type A1 we determine in closed form the difference operators for the basic defects, labeled by pr, qr and pq, and show that for odd r there exist additional elementary defects, whose operators shift the holonomy by one half modulo r. All the operators commute, and the elementary operators generate the others. For even r the same holds once the holonomy is extended to a twisted sector. We show that the elementary operators are traces of L-operators whose entries generate a Sklyanin algebra, with nome qr and shift pq. The lens space enters only through the parameters of the algebra and through its representation, which is realized on a doubled holonomy label. The p- and q-type algebras form a lens space version of the elliptic modular double. For class ๐ฎk theories we propose, and test in several ways, that the defect operators are transfer matrices of inhomogeneous spin chains built from these L-operators. Throughout, we use the TQFT structure of the lens space index, which follows from S-duality, both to fix and to check the operators.
Related
- Surface Defects in the ๐ฉ=2 Lens Space Index and Elliptic Integrability
- The Fourier Uncertainty Principle Through the Lens of Infinite Banded Matrices
- Supercritical magnetic ray transforms in hyperbolic space: the complexification method from the transport-twistor lens
- Lens space surgeries on knots of small genus
- Odd-dimensional lens-space Yamabe counterexamples
BibTeX
@misc{maruyoshi2026surface,
title = {{Surface defects on lens space and transfer matrices}},
author = {Kazunobu Maruyoshi and Toshihiro Ota and Masahito Yamazaki},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.28165},
eprint = {2610.28165},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.28165},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Surface defects on lens space and transfer matrices
AU - Kazunobu Maruyoshi
AU - Toshihiro Ota
AU - Masahito Yamazaki
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.28165
UR - https://arxiv.org/abs/2610.28165
AB - We study surface defects in four-dimensional ๐ฉ=2 theories of class ๐ฎ and ๐ฉ=1 theories of class ๐ฎ_k placed on L(r,1)ร S^1. The lens space index depends on the fugacities p and q, and the effect of the defects on it is captured by difference operators acting on the fugacities and holonomies of flavor symmetries. For theories of type A_1 we determine in closed form the difference operators for the basic defects, labeled by p^r, q^r and pq, and show that for odd r there exist additional elementary defects, whose operators shift the holonomy by one half modulo r. All the operators commute, and the elementary operators generate the others. For even r the same holds once the holonomy is extended to a twisted sector. We show that the elementary operators are traces of L-operators whose entries generate a Sklyanin algebra, with nome q^r and shift pq. The lens space enters only through the parameters of the algebra and through its representation, which is realized on a doubled holonomy label. The p- and q-type algebras form a lens space version of the elliptic modular double. For class ๐ฎ_k theories we propose, and test in several ways, that the defect operators are transfer matrices of inhomogeneous spin chains built from these L-operators. Throughout, we use the TQFT structure of the lens space index, which follows from S-duality, both to fix and to check the operators.
ER -