Roman Bessonov

University of Ljubljana
Faculty of Mathematics and Physics
Jadranska ulica 19
1000 Ljubljana, Slovenia
Office: J21 104

roman.bessonov@fmf.uni-lj.si
I'm an associate professor at the University of Ljubljana, Slovenia. I'm interested in spectral and scattering theory, orthogonal polynomials, complex analysis, Hankel and Toeplitz operators, and, more broadly, in the interplay of function and operator theories with applications in mathematical physics.

Seminar

With A. Kostenko and U. Jezernik, we are running the Spectral Theory Seminar at the University of Ljubljana and IMFM.

News

Employment

2024-now Associate Professor
Faculty of Mathematics and Physics, University of Ljubljana, Slovenia
2025-now Researcher
Institute of Mathematics, Physics and Mechanics, Ljubljana, Slovenia
2014-2025Researcher
St.Petersburg Department of V.A.Steklov Institute of Mathematics, Russia
2018-2024Associate Professor
St.Petersburg State University, Russia
2014-2018Researcher
Chebyshev Laboratory, St.Petersburg State University, Russia
2013-2014Postdoctoral fellow
School of Mathematical Sciences, Tel Aviv University, Israel

Education

2013         PhD (candidate of science degree) in Mathematics
St.Petersburg Department of V.A.Steklov Institute of Mathematics, Russia
Supervisor: V.V.Kapustin
2009Specialist degree in Mathematics
St.Petersburg State University, Russia
Supervisor: V.P.Havin

Projects

J1-70033 Random matrices, graphs, and groups (with U. Jezernik and A. Kostenko, 2026-2029).

Students

Current: Igor Sergeev, Anton Kurdoblo
Former: Pavel Gubkin (PhD), Stepan Konenkov (BSc), Peter Kulikov (BSc), Georgii Arhipov (BSc)

I have research problems at various levels. Interested students are welcome to contact me.

Papers

Preprints of my papers are avaliable on this ArXiv webpage. For published versions please visit my profile on MathSciNet. See also ORCID, Google Scholar or COBISS. Here are some selected papers:
  • Direct and inverse spectral continuity for Dirac cperators (GAFA 2026, with P.Gubkin)
  • Reflectionless canonical systems (Advances 2024, with M.Lukic and P.Yuditskii)
  • Szego condition, scattering, and vibration of Krein strings (Inventiones 2023, with S.Denisov)
  • Zero sets, entropy, and pointwise asymptotics of orthogonal polynomials (JFA 2021, with S.Denisov)
  • A spectral Szego theorem on the real line (Advances 2020, with S.Denisov)
  • Duality theorems for coinvariant subspaces of H^1 (Advances 2015)
  • Symbols of truncated Toeplitz operators (JFA 2010, with A.Baranov and V.Kapustin)

Lecture notes

Here is a collection of my lecture notes from St.Petersburg (2016-2023). Most of them are written by students following my presentation on the blackboard. Warm thanks to Mikhail Opanasenko, who organized exellent typesetting and proofreading work. Please also find below the lecture notes of my course for doctorate students at the University of Ljubljana.


Last update: 22.03.2026