Thursday, 5 June 2025, 14:00
University of Belgrade, Faculty of Physics – Room 750

Asst. Prof. Dr Dragan Prekrat (Faculty of Pharmacy, Belgrade)

Title: Matrix Models on the Truncated Heisenberg Algebra

Abstract:

In this seminar, we will explore the properties of matrix models defined on the noncommutative space of the truncated Heisenberg algebra. We begin with the Grosse–Wulkenhaar model, well known for its renormalizability, and examine the relationship between this feature and its phase structure. We then present preliminary numerical results on a related non-renormalizable gauge model and propose a possible approach to address its challenges.

Asst. Prof. Dr Juraj Tekel (Comenius University, Bratislava)

Title: Fuzzy Onion Strikes Back

Abstract:

You will already have heard a talk by my colleague Samuel about the structure of layered fuzzy spheres known as the “fuzzy onion.” I will continue along this path and explain more about topics he did not have time to discuss, especially regarding promising research directions—from technical aspects such as fuzzification of the radial coordinate using spectral triples to conceptual issues such as the emergence of the onion as a solution of M-theory models.

Thursday, 29 May 2025, 14:00
University of Belgrade, Faculty of Physics – Room 750

Prof. Dr Dragoljub Dimitrijević (PMF Niš)

Title: Scalar Fields in Cosmology

Abstract:

Cosmological observational data has been collected over the last thirty years. These include the precise measurement of CMB radiation, evidence of the accelerated expansion of the Universe, the discovery of gravitational waves, an image of the black hole at the center of the supergiant elliptical galaxy, and many others. To study, for example, cosmological inflation or primordial black holes, we need to use real scalar fields in a curved spacetime background. The scalar fields in use are canonical and non-canonical. This talk provides an introduction to one interesting non-canonical scalar field—the tachyon scalar field.

Prof. Dr Andrzej Borowiec (Wrocław University, Wrocław)

Title: Scalar-Tensor Gravity Models and Their Application in Cosmology

Abstract:

Scalar-tensor gravity is the most straightforward generalization of Einstein’s metric gravity by adding a single scalar field. It can help solve several persistent problems of the original theory, such as non-renormalizability or the well-known dark energy and dark matter problems in cosmology. During this lecture, I will focus on the internal mathematical structure of this class of theories, the role of conformal transformations, frame choice, non-minimal coupling to the matter stress-energy tensor, and the significance of invariant quantities. I will explain the differences between purely metric, Palatini, and hybrid approaches and how they can be described in a unified framework. Finally, I will present concrete cosmological models and their analysis in the minisuperspace formalism, which allows arbitrary forms of the stress-energy tensor non-minimally coupled to the metric. In particular, I will discuss the possibility of separating dark from baryonic matter in line with cosmological data.

Thursday, 15 May 2025, 14:00
University of Belgrade, Faculty of Physics – Room 750

Prof. Dr Marija Dimitrijević Ćirić (Faculty of Physics, Belgrade)

Title: On the CEEPUS Programme and the QSGravCos Network

Abstract:

We will briefly introduce the idea behind the CEEPUS (Central European Exchange Program for University Studies) programme and the Quantum Spacetime, Gravity and Cosmology network, and discuss opportunities for student and staff mobility to academic institutions participating in this network.

Asst. Prof. Dr Samuel Kováčik (Comenius University, Bratislava)

Title: The Fuzzy Onion

Abstract:

Recently, a matrix formulation of a three-dimensional quantum space was proposed. The basic idea is that an (in)finite number of fuzzy spheres can be glued together in a specific way. During the seminar, we will discuss the construction of the model with some recent examples from field theory, quantum mechanics, and classical physics.

Wednesday, 5 June 2024, 11:00
University of Belgrade, Faculty of Physics – Room 661

Asst. Prof. Dr Juraj Tekel (Comenius University, Bratislava)

Title: Fuzzy Physics and Matrix Models

Abstract:

The unification of quantum mechanics and gravity predicts a drastic change in the notion of space and time, at least at the length scales where both these theories are important. One realization of spaces with such quantum structures is noncommutative and fuzzy spaces. I will describe their construction and description of physics happening in such spaces in terms of random matrix models. I will then explain some of the techniques and results for relevant examples of matrix ensembles.

Friday, 26 April 2024, 11:00
Institute of Physics Belgrade – Room 360

BSc Benedek Bukor (Comenius University, Bratislava)

Title: What about quarkonia in the (non)commutative space?

Abstract:

Quarkonium bound states are especially promising candidates to test the probable quantum structure of space-time since they represent a system with a reasonably small characteristic distance. Although the theory of quarkonia is quantum chromodynamics, the interaction between the quarks can be heuristically described by the quantum mechanical Cornell potential as well. Firstly, we investigate the quarkonium system in the 3-dimensional smooth configuration space. Thereafter, we insert it into a non-commutative 3-dimensional configuration space, which is composed of concentric fuzzy spheres of increasing radius, called the fuzzy onion, in order to extract some consequences of the non-trivial structure of the space by means of the quarks’ properties.

D. Prekrat, B. Bukor, J. Tekel

Pinpointing Triple Point of Noncommutative Matrix Model with Curvature

arXiv: 2505.07563 [hep-th]

status: PUBLISHED

M. Dimitrijević Ćirić, T. Jurić, N. Konjik, A. Samsarov, I. Smolić

Noncommutative Reissner–Nordström black hole from noncommutative charged scalar field

arXiv: 2404.03755 [hep-th]

status: PUBLISHED

M. Stojanović, N. Bilić, D. D. Dimitrijević, G. S. Djordjević, M. Milosević

Constant-roll inflation with tachyon field in the holographic braneworld

arXiv: 2401.00352 [gr-qc]

status: PUBLISHED

G. S. Đorđević, N. Bilić, D. D. Dimitrijević, M. Milošević, M. Stojanović

On attractor behavior in braneworld constant-roll inflation

arXiv: 2405.18420 [gr-qc]

status: PREPRINT

D. Prekrat, D. Ranković, N. K. Todorović-Vasović, S. Kováčik, J. Tekel

Phase transitions in a Φ⁴ matrix model on a curved noncommutative space

arXiv: 2310.10794 [hep-th]

status: PUBLISHED