What the study found
The study finds an upper bound on the number of Weyl points, meaning generic twofold energy-degeneracy points, that can arise when a multifold degeneracy point in a quantum system is perturbed.
Why the authors say this matters
The authors say their work helps connect physics and mathematics by using singularity theory and local algebraic geometry to describe degeneracy points in parameter-dependent quantum systems and related condensed-matter settings.
What the researchers tested
The researchers studied parameter-dependent quantum systems with energy degeneracy points, focusing on cases where three or more levels coincide at a single parameter point. They analyzed the associated geometric degeneracy variety in the space of complex matrices and computed multiplicities at singular points and of holomorphic map germs with respect to this variety.
What worked and what didn't
Their approach provided an upper bound for the number of Weyl points produced when a multifold degeneracy is generically perturbed. The abstract does not report a failure case or a competing method that did not work.
What to keep in mind
The abstract does not give the numerical value of the upper bound or detail any specific examples beyond the general setting. It also does not describe limitations beyond the scope of the singularity-theoretic framework used.
Key points
- The paper gives an upper bound on how many Weyl points can form from a multifold degeneracy.
- A multifold degeneracy means three or more energy levels coincide at one parameter point.
- The authors analyze a geometric degeneracy variety in the space of complex matrices.
- The work uses singularity theory and local algebraic geometry.
- The abstract says the paper surveys examples from quantum systems and condensed-matter physics.
Disclosure
- Research title:
- Upper bound estimated for Weyl points from multifold degeneracies
- Authors:
- György Frank, Gergő Pintér, Dániel Varjas, András Pályi
- Institutions:
- Budapest University of Technology and Economics, Leibniz Institute for Solid State and Materials Research, Complexity and Topology in Quantum Matter
- Publication date:
- 2026-04-20
- OpenAlex record:
- View
- Image credit:
- Photo by Google DeepMind on Pexels · Pexels License
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