Essential Singularity of the Correlation Length in the Planar XY Model

OpenAI

For the nearest-neighbor cosine XY model on the square lattice, the manuscript claims sqrt(βc−β) log ξ(β) tends to a finite positive model-specific constant as β rises to βc from below. Here ξ is defined from the inverse axis mass after the infinite-volume and separation limits in that order.

Sources for this record

What was already known

Kosterlitz–Thouless theory predicted the essential singularity. Earlier results established phase and decay information or treated related Villain and Coulomb-gas models under different assumptions.

AI involvement AI-led

OpenAI attributes this manuscript and its two companion critical-correlation inputs to its internal model.

The OpenAI-authored paper and release document central internal-model production, but do not establish AI-autonomous session conditions.

Importance Major

This proves the predicted correlation-length scaling for the ordinary square-lattice cosine XY model.

Limitations

The constant is not given in closed form. The proof uses two companion critical-correlation results, and no completed check of this theorem or those inputs is documented.

Technical verification Reported

The manuscript provides a proof that depends on two companion model-produced critical results, but the cited release documents no completed human or machine check of this full essential-singularity theorem. Reported is the evidence default.

Human understanding Few

No named human account explains the central temperature-response and correlation-length conversion; Few is the evidence default, not a finding that people cannot understand it.

Correction and publication history

2026-10-18 · publication

If correct, this proves the predicted correlation-length scaling for the ordinary square-lattice cosine XY model.

Read this published revision