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Time: 24. April 2026, 11:00h
Place: Institute of Physics, room 360
Speaker: Matej Males
Title: Phenomenology of the minimal noncommutative Standard Model in the process qq->ZZ->4l
Abstract:
In this presentation we consider the process qq->ZZ, within the framework of the noncommutative Standard Model. After a brief motivation and a review of the basic characteristics of the Standard Model, we introduce the noncommutative star product. We follow the basic consequences of the Moyal–Weyl product and the Seiberg–Witten mappings on the form of the action, after which we restrict ourselves exclusively to the framework of the minimal noncommutative Standard Model. In the given model we examine from which parts of the action new terms relevant to our process are obtained. We focus on the newly arising vertex corrections, contact contributions, and contributions of the ZZZ vertex, where we go through the main differences in the calculation of Feynman amplitudes compared to the uncorrected Standard Model. We present the results of the calculation, and discuss potential further steps.
Time: 3. April 2026, 11:00h
Place: Institute of Physics, room 360
Speaker: Pavle Stipsic
Title: A 3BF model of quantum gravity coupled to Standard Model matter
Abstract:
We develop an explicit model of quantum gravity coupled to the matter fields of the Standard Model, based on the 3-group structure and the 3BF action, within the framwork of higher gauge theory. The model is constructed by providing a rigorous definition for the path integral of the theory, achieved by defining the whole theory on a piecewise-flat spacetime manifold. To that end, we develop a method to systematically discretize both the action and the path integral measure by passing from a smooth manifold to a piecewise-flat manifold. Finally, we discuss in some detail the structure of the resulting quantum gravity model, and provide a preliminary analysis of its semiclassical limit.
Time: 20. March 2026, 13:00h
Place: Institute of Physics, room 360
Speaker: Thomas Basile
Title: Introduction to (multisymplectic) AKSZ sigma models
Abstract:
The Alexandrov–Kontsevich–Schwarz–Zaboronsky (AKSZ) construction provides a way to build topological sigma models starting from certain graded manifolds equipped with geometric structures (namely a symplectic form and a compatible nilpotent vector field of degree 1). In this talk, I will begin with an introduction to AKSZ sigma models and review how these structures on the target space graded manifold allow one to define gauge-invariant field theories formulated in a covariant, multidimensional, analogue of the first-order Hamiltonian formalism.
I will then present a generalisation which gives rise to higher-derivative extensions of AKSZ-type actions, using a version of the Chern–Weil morphism adapted to graded manifolds. As an illustration, I will discuss how several familiar gauge theories such as higher-dimensional Chern–Simons theory, MacDowell–Mansouri–Stelle–West gravity, and self-dual gravity with its higher-spin extensions, fit naturally into this framework.
Based on arXiv:2601.16785 with Maxim Grigoriev and Evgeny Skvortsov.
Time: 20. March 2026, 11:00h
Place: Institute of Physics, room 360
Speaker: Nikola Paunkovic
Title: Quantum information geometry and applications to phase transitions of many-body systems
Abstract:
As an introduction, I will briefly overview the main research directions throughout my career: (i) quantum information theory, (ii) quantum cryptography, (with the emphasis on security protocols beyond key distribution), (iii) interface between quantum mechanics and quantum gravity, and (iv) information geometry and applications, which will be the focus of this talk.
I will present an overview of information geometry of quantum states and its application to the study of phase transitions in many-body systems, with a special focus on the results I was involved in during the past 20 years of research. On the example of classical physics and probability distributions, I will first briefly introduce how the notions of information and geometry fit in the description of this line of research. Then, I will analyse in more detail three particular geometries of quantum states: a pure-state U(1) Berry gauge geometry, and two distinct mixed state geometries, one equipped with U(N) gauge group (Uhlmann), as well as the so-called interferometric geometry obtained from a symmetry broken Uhlmann gauge group [U(N) --> \otimes_i U(N_i), with \sum_i N_i = N]. I will then move to describe the so-called fidelity approach to the study of phase transitions. Being based on an abstract notion of state distinguishability (the notion that gives rise to information geometry), it is intended to present a general approach to the study of phase transitions that goes beyond Landau Ginzburg and other partial approaches. I will introduce the so-called fidelity susceptibility (a metric field over the space of states) and discuss it on a few examples of many-body systems, showing its explicit connection to dynamical susceptibilities of both zero-temperature quantum and finite-temperature equilibrium phase transitions. If time permits, I will also briefly discuss recently introduced non-equilibrium dynamical phase transitions and their connection to the geometry of channels and processes.
Time: 6. March 2026, 11:00h
Place: Institute of Physics, room 360
Speaker: Andrei Egorov
Title: Black holes: implications for dark matter searches and theories of gravity
Abstract:
My talk will contain two major parts. The first part will be dedicated to my new work about detection prospects for heavy DM particles (WIMPs) near supermassive black holes (SMBHs). SMBHs are expected to form density spikes of annihilating DM. Such spikes may be detectable in the gamma-ray band even in the case of the heaviest WIMPs, which are not observable otherwise. Only two closest SMBHs are shown to be relevant for WIMP searches: MW* and M31*. I estimated the sensitivity of upcoming Cherenkov Telescope Array to the potential WIMP signal from those targets. The second part of my talk will review semi-qualitatively the implications and possibilities of BH observations for testing theories of gravity (including quantum ones). Thus, I cover current and future observations of gravitational waves, SMBH shadows, isolated stellar BHs, MW nuclear star cluster and others. Finally, a summary of the current synergy between theory and observations will be given.
Time: 20. February 2026, 11:00h
Place: Institute of Physics, room 360
Speaker: Igor Prlina
Title: If quantum measurements are secretly continuous nonunitary processes, weak measurements can detect it
Abstract:
The standard approach to quantum measurements is to assume that they lead to effectively instantaneous collapse of the quantum state. However, if we assume that we are unable to enforce at what exact moment of time the measurement occurs due to a finite resolution of any time measurement device, at the level of the ensemble the measurement would lead to an effectively nonunitary evolution involving a mixed state. Each individual ensemble member would face an instantaneous collapse at different moments of time. This process is completely indistinguishable from fundamental nonunitary evolution at the level of each individual ensemble member, within the framework of strong projective measurements. In this talk, we will show that weak postselected measurements can distinguish these two types of evolution. An experimental protocol for determining the nature of quantum collapse based on a simultaneous application of a weak and a strong measurement will be described, and the example of a hydrogen atom will be analyzed in detail.
Time: 6. February 2026, 11:00h
Place: Institute of Physics, room 360
Speaker: Danilo Rakonjac
Title: Extremal Kerr-AdS black hole with torsion: near-horizon geometry
Abstract:
Despite the fact that extremal black holes in general relativity have a well defined concept of near-horizon geometry, it is not always the case in the presence of torsion. Covariant geometric conditions of existence of the near-horizon limit, which defines this geometry, are derived for the case of non-zero torsion. Finally, a model of Kerr-AdS black hole with torsion which has a well defined near-horizon geometry in the extremal case, is presented.
Seminars for the year:
2026
2025
2024
2023
2022
2021
2020
2019
2018
2017
2016
2015
2014
2013
2012
2011
2010
2009
2008
2007
Follow our seminars online via: GPF BigBlueButton server
