2025/12/11 by Max Downing, Downing, Max, Jesper Lykke Jacobsen +7
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #FOS: Physical sciences #High Energy Physics - Theory (hep-th) #High-Energy Particle Collisions Research #Mathematical Physics (math-ph) #Statistical Mechanics (cond-mat.stat-mech)
paper · pdf · doi:10.48550/arxiv.2512.10400
openalex publication_date 2025/12/11 · openalex created_date 2025/12/13 · openalex updated_date 2026/07/28
In critical loop models, we define diagonal boundaries as boundaries that couple to diagonal fields only. Using analytic bootstrap methods, we show that diagonal boundaries are characterised by one complex parameter, analogous to the boundary cosmological constant in Liouville theory. We determine disc 1-point functions, and write an explicit formula for disc 2-point functions as infinite combinations of conformal blocks. For a discrete subset of values of the boundary parameter, the boundary spectrum becomes discrete, and made of degenerate representations. In such cases, we check our results by numerically bootstrapping disc 2-point functions. We sketch the interpretation of diagonal boundaries in lattice loop models. In particular, a loop can neither end on a diagonal boundary, nor change weight when it touches it. In bulk-to-boundary OPEs, numbers of legs can be conserved, or increase by even numbers.