A New Entropy Puzzle in ABJM

@misc{belin2026entropy,
  title = {{A New Entropy Puzzle in ABJM}},
  author = {Alexandre Belin and Seyed Morteza Hosseini and Palash Singh and Rita Vadala and Alberto Zaffaroni},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.07135},
  eprint = {2610.07135},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.07135},
}

TY  - UNPB
TI  - A New Entropy Puzzle in ABJM
AU  - Alexandre Belin
AU  - Seyed Morteza Hosseini
AU  - Palash Singh
AU  - Rita Vadala
AU  - Alberto Zaffaroni
PY  - 2026
DA  - 2026/10/05
PB  - arXiv
DO  - 10.48550/arxiv.2610.07135
UR  - https://arxiv.org/abs/2610.07135
AB  - We point out a puzzle about BPS black holes in AdS_4× S^7/ℤ_k: the entropy grows when k increases although the number of gauge-invariant operators in the dual conformal field theory that can contribute to the entropy grows as k decreases, due to the presence of monopole operators. Analyzing the superconformal index of ABJM, we show that the same puzzle exists for finite N in the large charge limit. We propose a resolution based on an increasing number of trace relations as k decreases, which dominates over the other effect. We argue that this mostly affects fortuitous operators and we provide an explicit example of a fortuitous operator that disappears at small k.
ER  -