ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

okt. 17. péntek 10h15,

1111 Budapest, Budafoki út 8., BME F III. magasföldszint 01.,
Elméleti Fizika Tanszék szemináriumi szoba

Pintér Gergő (BME Elm. Fiz. tanszék):
Upper bound on the number of Weyl points born from a multifold degeneracy
point

Parameter-dependent quantum systems often exhibit energy degeneracy points,
whose comprehensive description naturally leads to the application of
methods from singularity theory. A prime example is an electronic band
structure where two energy levels coincide in a point of momentum space.
It may happen, and this case is our focus, that three or more levels
coincide at a parameter point, called multifold degeneracy. For example,
the Hamiltonian of a spinful particle in an external magnetic field has a
(2s+1) -fold degeneracy for zero magnetic field, where s is the total spin.
Upon a generic perturbation, such a multifold degeneracy point is dissolved
into a set of Weyl points, that is, generic two-fold degeneracy points. We
provide an upper bound to the number of Weyl points born from a multifold
degeneracy point. Our work attempts to bridge two disciplines, quantum
mechanics and singularity theory (algebraic geometry).

Joint work with György Frank, Dániel Varjas, András Pályi with a
significant contribution of Alex Hof.
https://arxiv.org/abs/2507.17485

Minden érdeklődőt szeretettel várunk.
Asbóth János,
 szemináriumi koordinátor