Department of Theoretical Physics

Marin Šako, PhD presentation
2026-04-13 13:00 - 14:00 (Europe/Ljubljana) | A/1-106 – Seminarska soba fizike (F5) (Jamova)
https://indico.ijs.si/event/3734/

Rishav Roshan: Gravitational wave production during reheating: From the inflaton to primordial black holes
2026-04-16 11:00 - 12:00 | A/1-106 – Seminarska soba fizike (F5)
We calculate the gravitational waves (GWs) produced by primordial black holes (PBHs) in the presence of the inflaton condensate in the early Universe. Combining the GW production from the evaporation process, the gravitational scattering of the inflaton itself, and the density fluctuations due to the inhomogeneous distribution of PBHs, we propose for the first time a complete, coherent analysis of the spectrum, revealing three peaks, one for each source. Three frequency ranges (~kHz, GHz, and PHz, respectively) are expected, each giving rise to a similar GW peak amplitude Ω_GW. We also compare our predictions with current and future GW detection experiments.
https://indico.ijs.si/event/3730/

Markus Miettinen, "High-fidelity biomolecular modelling"
2026-04-20 13:00 - 14:00 | MPŠ Lecture Hall (Jamova)
https://indico.ijs.si/event/3733/

Elie Hammou: Tailored PDFs for new physics searches
2026-05-07 11:00 - 12:00 | A/1-106 – Seminarska soba fizike (F5)
https://indico.ijs.si/event/3731/

Andraž Stožer & Marko Gosak, "From Ca²⁺ Waves to Insulin Pulses: Experimental and Theoretical Perspectives on β-Cell Network Dynamics"
2026-05-14 14:15 - 15:15 | Seminar room of physics (106) (IJS)
Pancreatic β-cells within the islets of Langerhans coordinate their activity to generate pulsatile insulin secretion, a process essential for glucose homeostasis and disrupted during the development of diabetes. This seminar will combine experimental physiology and mathematical modelling to examine how multicellular β-cell networks encode, propagate, and translate Ca²⁺ signals into insulin release. In the experimental part, we will present insights from high-frequency confocal Ca²⁺ imaging, showing how β-cells respond heterogeneously to stimulation, how fast Ca²⁺ oscillations and intercellular waves emerge within islets, and how specific cellular subpopulations may contribute to signal initiation and propagation. We will also discuss conserved and altered features of these dynamics in human islets and during diabetes progression. Building on these findings, the modelling part will address why mathematical abstraction is needed to disentangle the mechanisms underlying such complex multiscale behaviour. We will present a phenomenological multicellular model that links structural gap-junction coupling, timescale-specific functional connectivity, and secretion. The model reproduces experimentally observed slow metabolic oscillations, fast bursts, and ultrafast spikes, and shows how interactions between these temporal domains shape pulsatile insulin output. By integrating high-resolution Ca²⁺ imaging with phenomenological modelling, the seminar highlights how interdisciplinary approaches can reveal the principles governing β-cell network function and its disruption in diabetes.
https://indico.ijs.si/event/3643/

Urška Andrenšek, "Elasto-capilary vertex model of epithelia"
2026-05-28 14:00 - 15:00 | A/1-106 – Seminarska soba fizike (F5) (Jamova)
https://indico.ijs.si/event/3732/

Ezequiel Alvarez: Leveraging Biased Simulations with Bayesian inference
2026-06-02 11:00 - 12:00 | F1 tea room
Scientific measurements often yield data that are mixtures of signal and one or more background components. When class templates (e.g., simulation-based priors) are biased or imprecise, they are typically treated as nuisance systematics. We take a different route: by embedding imprecise priors in a hierarchical Bayesian mixture model and combining them with observed mixed data via Bayesian machine learning, we adapt class shapes toward the true distributions and obtain an unbiased posterior estimate of the signal fraction with calibrated uncertainties. In practice this lets us exploit simulation even when it is imperfect—improving template fidelity during inference. We demonstrate the approach on a collider-physics example (di-Higgs → 4b at the LHC), and show how the same framework can enhance and unbias the ABCD background-estimation method. The framework, Template-Adapted Mixture Model (TAMM, arXiv:2604.022219), is straightforward to implement, scales to high-dimensional and complex distributions, and is broadly applicable across HEP, astrophysics, cosmology, and any domain with mixed data and imperfect priors.
https://indico.ijs.si/event/3833/

Ekaterina Poliukhina, "Direct measurement of protein-protein interaction potentials by cryo-electron tomography"
2026-06-18 14:00 - 15:00 | A/1-106 – Seminarska soba fizike (F5) (Jamova)
Protein-protein interactions control how proteins behave in solution, dictating aggregation, crystallization, phase separation, and the colloidal stability of formulations central to pharmacology, food science, and biotechnology. Predicting this behavior has long been difficult: theories borrowed from classical colloid science fail for proteins, which are irregularly shaped and chemically heterogeneous, and no direct experimental route to the underlying interaction potential has been available. Cryo-electron tomography now provides such a route. By reconstructing three-dimensional tomograms containing thousands of individual proteins, the spatial distribution of every particle can be recovered and converted, without any assumed functional form, into a measured interaction potential. Validated against analytical ultracentrifugation and small-angle X-ray scattering, the approach spans globular proteins from lysozyme to apoferritin and reveals how ionic strength, pH, temperature, and additives reshape their interactions.
https://indico.ijs.si/event/3599/

Maximilian Bachmaier: The slingshot effect and its cosmological implications
2026-07-16 11:00 - 12:00 | A/1-106 – Seminarska soba fizike (F5) (Jamova)
In my talk, I will present the so-called slingshot effect. It represents a general phenomenon that occurs when a localized source, such as a magnetic monopole, quark, or a D-brane, crosses a wall separating the confined (Higgsed) and unconfined (Coulomb) phases. The crossover is accompanied by a stretched string that confines the source to the wall. The string tension accelerates the source towards the wall as sort of a slingshot. The effect can take place in different setups, such as phase transitions leading to both electric and magnetic confinement, as well as in string cosmology involving D-branes. I will discuss the role of this phenomenon in sourcing gravitational waves.
https://indico.ijs.si/event/3895/
