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Classification of c=1 CFTs
Abstract
We completely classify unitary 2d CFTs with central charge c=1 and discrete spectrum. We confirm the folklore that the only such theories are the compact free boson, its ℤ2-orbifold, and three exceptional theories obtained as orbifolds of the SU(2)1 WZW model. The proof is by recasting the c=1 modular bootstrap as a crystalline measure problem for the density of states, and analytically solving it. We also show that, once the density of states is specified, the full CFT can be uniquely reconstructed.
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BibTeX
@misc{eberhardt2026classification,
title = {{Classification of c=1 CFTs}},
author = {Lorenz Eberhardt and Nat Levine},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.16111},
eprint = {2609.16111},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.16111},
}
RIS
TY - UNPB
TI - Classification of c=1 CFTs
AU - Lorenz Eberhardt
AU - Nat Levine
PY - 2026
DA - 2026/09/14
PB - arXiv
DO - 10.48550/arxiv.2609.16111
UR - https://arxiv.org/abs/2609.16111
AB - We completely classify unitary 2d CFTs with central charge c=1 and discrete spectrum. We confirm the folklore that the only such theories are the compact free boson, its ℤ_2-orbifold, and three exceptional theories obtained as orbifolds of the SU(2)_1 WZW model. The proof is by recasting the c=1 modular bootstrap as a crystalline measure problem for the density of states, and analytically solving it. We also show that, once the density of states is specified, the full CFT can be uniquely reconstructed.
ER -