English

Certain real surfaces in $\mathbb{C}^2$ with degenerated CR singularities

Complex Variables 2026-07-19 v1

Abstract

In this paper, we study the local polynomial convexity of certain smooth real surfaces in C2\mathbb{C}^2 with isolated CR singularity at the origin with higher-order of degeneracy. Under the assumption that the surface can be pulled back to a union of finitely many pairwise transverse totally real surfaces by a proper holomorphic map from C2\mathbb{C}^2 to C2\mathbb{C}^2, we obtain a normal form for such surfaces near the origin as {(z,w)C2:w=zk+o(zk)}\{(z,w)\in\mathbb{C}^2: w= \overline{z}^k+o(|z|^{k})\} or Mt:={(z,w)C2:w=(z+tz)k+o(zk)}M_t := \left\{ (z,w)\in\mathbb{C}^2 : w=(z+t\overline{z})^k+o(|z|^k) \right\}, for some t>0t>0, where the parameter tt is a local biholomorphic invariant. We focus on the surfaces with order of degeneracy k3k\geq 3. We prove that MtM_t is locally polynomially convex at the origin if t>cosec(πk)t>cosec\left(\frac{\pi}{k}\right). On the other hand, for 0<t<1k20<t<\frac{1}{k-2}, we will also show that MtM_t fails to be locally polynomially convex at the origin; and furthermore, a (2k3)(2k-3)-parameter family of analytic discs attached to MtM_t for 0<t<min{sin(πk),1k2}0<t<\min\left\{\sin\left(\frac{\pi}{k}\right),\frac{1}{k-2}\right\}.

Cite

@article{arxiv.2607.17016,
  title  = {Certain real surfaces in $\mathbb{C}^2$ with degenerated CR singularities},
  author = {Sushil Gorai and Suman Karak and Golam Mostafa Mondal},
  journal= {arXiv preprint arXiv:2607.17016},
  year   = {2026}
}

Comments

22 pages, comments are welcome