Defect conformal field theories with free-in-the-bulk fermions

@misc{herzog2026defect,
  title = {{Defect conformal field theories with free-in-the-bulk fermions}},
  author = {Christopher P. Herzog and Daniel Lloyd-Jones},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.14176},
  eprint = {2610.14176},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.14176},
}

TY  - UNPB
TI  - Defect conformal field theories with free-in-the-bulk fermions
AU  - Christopher P. Herzog
AU  - Daniel Lloyd-Jones
PY  - 2026
DA  - 2026/10/09
PB  - arXiv
DO  - 10.48550/arxiv.2610.14176
UR  - https://arxiv.org/abs/2610.14176
AB  - We study codimension-two conformal defects for massless fermions that are free in a four-dimensional bulk, but interact on a two-dimensional defect. The bulk Dirac equation strongly constrains defect conformal field theory data: it fixes the dimensions of operators in the bulk-defect operator product expansion and, for bulk-defect-defect three-point functions, enforces a double-twist relation when only one member of a shadow pair is allowed by unitarity. The lowest modes of monodromy defects provide an important exception, since both shadow partners can be unitary and their three-point functions are instead related by a shadow transform. We illustrate these structures with defect interactions, including an exactly tractable bilinear flow and Gross-Neveu-type quartic couplings. At a perturbative mixed fixed point, we find an explicit interacting example in which the double-twist condition is violated and the two shadow channels combine to give a regular bulk-defect-defect correlation function.
ER  -