Sifan Yin, "Developmental mechanics of divergent buckling patterns in chick gut"
2025-03-27 14:00 - 15:00 (Europe/Ljubljana) | A/1-106 – Seminarska soba fizike (F5) (Jamova)
https://indico.ijs.si/event/2785/

Borut Bajc: E6
2025-04-08 14:00 - 15:00 | C/2-X – F1 čajnica (Jamova)
I will motivate the use of E6 grand unified theory and describe a
realistic E6 GUT which gives rise to novel possible intermediate stages.
https://indico.ijs.si/event/2874/

Stephane Jedele, "Study of the KCNN4 channel involved in the pathological dehydration of red blood cells using molecular modeling approaches"
2025-04-09 12:15 - 13:15 | C/2-X – F1 čajnica (Jamova)
KCNN4 is a calcium (Ca)-activated potassium (K+) channel translocating K+ ions across several cellular membranes and for which Ca2+ sensitivity is conferred by calmodulin (CaM). Until the main part of the protein structure bound to CaM has been resolved, in silico studies had used homology models derived from the well characterized transmembrane domain of other K+ channels, limiting the functional investigation to this particular region. Thus, how the regulatory domains of KCNN4 communicate with each other and where the possible gates are located across the complete structure are still not well understood. My PhD work presents for the first time results obtained from an extensive investigation of full-length models of the channel in different conformational states and molecular contexts using all-atom molecular dynamics simulations and enhanced sampling methods. The results allow us to contextualize no less than 6 of the pathogenic mutations identified in the channel to date, and provide a new basis for understanding the KCNN4 function.
https://indico.ijs.si/event/2866/

Sascha Ollertz, "Agent-based modelling of cell differentiation patterns in mouse blastocysts"
2025-04-10 12:30 - 13:30 | C/2-X – F1 čajnica (Jamova)
Early embryonic development from zygote to blastocyst is a highly dynamic, self-organised process in which stem cells undergo successive cell fate decisions and form a complex structure. Local patterns in the early and mid blastocyst stage resolve into global patterns in the late stage of the blastocyst . A first modelling approach, based on cell division and signalling showed that the spatial cell fate patterns arising in the earlyand mid stage, are compatible with signalling beyond the nearest neighbours . As a next step, we expanded our existing mathematical, agent-based model to incorporate the late stage by including cell sorting based on differential adhesion. The resulting model consists of cell division, cell death, physical interactions, transcription and signalling between the cells. The model allows us to systematically investigate the influence of these mechanisms and their relative timing with respect to the formation of the global pattern in the late blastocyst stage.
Fischer, S. C., Corujo-Simon, E., Lilao-Garzon, J., Stelzer, E. H. K., & Muñoz-Descalzo, S. (2020). The transition from local to global patterns governs the differentiation of mouse blastocysts. PloS one, 15(5), e0233030.
Fischer, S. C., Schardt, S., Lilao-Garzón, J., & Muñoz-Descalzo, S. (2023). The salt-and-pepper pattern in mouse blastocysts is compatible with signaling beyond the nearest neighbors. In iScience (Vol. 26, Issue 11, p. 108106).
Schardt, S., & Fischer, S. C. (2023). Adjusting the range of cell-cell communication enables fine-tuning of cell fate patterns from checkerboard to engulfing. Journal of mathematical biology, 87(4), 54.
https://indico.ijs.si/event/2746/

Fran Ivan Vrban, "Variational model shapes of deformable particles"
2025-04-17 14:00 - 15:00 | A/1-106 – Seminarska soba fizike (F5) (Jamova)
https://indico.ijs.si/event/2782/

Jonathan Kriewald: Lepton Number Violation at the LHC
2025-04-17 15:30 - 16:30 | https://zoom.us/j/3601731049?pwd=[REDACTED] (A/1-106 – Seminarska soba fizike (F5))
Numerous well-motivated extensions of the Standard Model, notably models linked to the generation of neutrino masses and to searches for neutrinoless double-beta decay, predict the existence of lepton-number-violating (LNV) processes. In particular, the type II seesaw and the left-right symmetric model predict final states consisting of same-sign di-leptons with jets and/or the existence of long-lived heavy neutral leptons which could be detected at the LHC.
In this talk I will review current collider limits on such scenarios and estimate the corresponding future HL-LHC sensitivities for these models. I will show that these models predict observable signals across broad regions of parameter space, whereas the LHC can indirectly probe New Physics scales as high as 70-80 TeV.
https://indico.ijs.si/event/2903/

Matej Kanduč, "Microplastics through the lens of physics"
2025-04-24 14:00 - 15:00 | A/1-106 – Seminarska soba fizike (F5) (Jamova)
Micro- and nanoplastics have emerged as persistent and pervasive pollutants, raising concerns across environmental and biological systems. In this talk, I will show how we can use ideas from soft matter physics, especially colloid and interface science, to better understand how these particles behave. We will look at how nano- and microplastics act like colloids and how their movement and interactions depend on their surface properties and the conditions around them.
https://indico.ijs.si/event/2858/

Yue Zhang: Neutrino Self-interaction: Motivations and Future Probes
2025-04-29 14:00 - 15:00 | https://zoom.us/j/3601731049?pwd=[REDACTED] (C/2-X – F1 čajnica)
Neutrino self-interaction with a larger “Fermi constant” is often resorted for understanding puzzles of our universe. I will first discuss how novel neutrino self-interactions can save the sterile neutrino dark matter produced through early universe oscillation mechanism, which is otherwise ruled out by cosmological observations. The explanation requires the existence of a light scalar boson that couples exclusively to neutrinos and sets a well-motivated target for experimental probes. In the second part of talk, I will review existing constraints on the neutrinophilic scalar, and point out pathways for testing the model in upcoming experiments.
https://indico.ijs.si/event/2582/

Angelo Rosa, "Configurational entropy of random trees"
2025-05-08 14:15 - 15:15 | Seminar room of physics (106) (IJS)
In this talk, I will illustrate two recent results of our group concerning the statistical physics of branched polymers. In the first part, I will present a graph theoretical approach to the configurational statistics of random tree-like objects, which is based on Prüfer labelling. The method, in particular, provides: (i) direct access to the exact configurational entropy as a function of the tree composition, (ii) computable exact expressions for partition functions and important experimental observables for tree ensembles with controlled branching activity and (iii) an efficient sampling scheme for corresponding tree configurations and arbitrary static properties. Then, in the second part, I will introduce a field-theoretic framework for branched polymers with excluded volume interactions. By solving the corresponding partition function by mean-field methods, I will show that the theory is in semi-quantitative agreement with Monte-Carlo computer simulations.
https://indico.ijs.si/event/2878/

Marko Malezic: Toward Efficient Trotter-Suzuki Schemes for Long-Time Quantum Dynamics
2025-05-20 15:30 - 16:30 | https://zoom.us/j/3601731049?pwd=[REDACTED] (F1 tea room)
Accurately simulating long-time dynamics of quantum many-body systems—whether in real or imaginary time—is a challenge in both classical and quantum computing due to the accumulation of Trotter errors. While low-order Trotter-Suzuki decompositions are straightforward to implement, their rapidly growing error limits access to long-time observables and ground state properties. I will present a framework for constructing efficient high-order Trotter-Suzuki schemes by identifying their structure and directly optimizing their parameters over a high-dimensional space. This method enables the discovery of new schemes with significantly improved efficiency compared to traditional constructions, such as those by Suzuki and Yoshida. I will demonstrate the effectiveness of these decompositions on the Heisenberg XXZ model, comparing their performance and presenting the newly discovered schemes. Finally, I will discuss ongoing efforts to extend this framework to even higher orders and apply the derived schemes to quantum hardware, pushing the boundaries of both theoretical advancements and practical quantum computing.
https://indico.ijs.si/event/2921/

Anže Božič, "Complexity of RNA sequences"
2025-05-29 14:00 - 15:00 | A/1-106 – Seminarska soba fizike (F5) (Jamova)
https://indico.ijs.si/event/2913/

Motoo Suzuki: Small Instantons and the Post-Inflationary QCD Axion in a Special Product GUT
2025-05-29 15:30 - 16:30 | https://zoom.us/j/3601731049?pwd=[REDACTED] (A/1-106 – Seminarska soba fizike (F5))
In this talk, after some review of axion physics, I would like to discuss our recent work about a new framework of grand unification that is equipped with an axion solution to the strong CP problem without a domain wall problem when the Peccei–Quinn (PQ) symmetry is spontaneously broken after inflation. Our grand unified theory (GUT) is based on a symmetry breaking pattern, SU(10) ×SU(5)1 →SU(5)V ⊃SU(3)C ×SU(2)L ×U(1)Y, where SU(5)1 and a special embedding of SU(5)2 ⊂SU(10) are broken to a diagonal subgroup SU(5)V. The model contains a vector-like pair of PQ-charged fermions that transform as (anti-)fundamental representations under SU(10), so that the domain wall number is one. However, after the GUT symmetry breaking, the number of vector-like pairs of PQ-charged colored fermions is larger than one, which seems to encounter the domain wall problem. This apparent inconsistency is resolved by small instanton effects on the axion potential which operate as a PQ-violating bias term and allow the decay of domain walls. We propose a domain-wall-free UV completion for an IR model where the domain wall number appears larger than one. The model gives a prediction for a dark matter axion window, which is different from that of the ordinary post-inflationary QCD axion with domain wall number one.
https://indico.ijs.si/event/2901/

Yutaro Shoji: Regularization of Functional Determinants of Radial Operators via Heat Kernel Coefficients
2025-06-05 15:30 - 16:30 | https://zoom.us/j/3601731049?pwd=[REDACTED] (A/1-106 – Seminarska soba fizike (F5))
The leading order quantum corrections in quantum field theory appear in the form of functional determinants, and their evaluation is very important in theoretical and phenomenological studies. We propose an efficient regularization method using the heat kernel coefficients. It enables us to regularize functional determinants in higher dimensions. In particular, our explicit formulas can regularize functional determinants in up to 13 dimensions, which has been a very difficult task before our study. The formulas can also be used to approximate higher angular momentum contributions in lower dimensions, which makes the numerical computation very efficient. The large angular momentum expansion of our formula gives the WKB formulas in the previous studies, but extended to higher orders. The results are obtained in both the zeta function regularization and the dimensional regularization.
https://indico.ijs.si/event/2974/

Masayuki Imai, "From Vesicles to Synthetic Minimal Cells"
2025-06-12 14:15 - 15:15 | A/1-106 – Seminarska soba fizike (F5) (Jamova)
Life is a self-sustaining system that continuously proliferates by synthesizing membrane molecules from external raw materials, thereby enabling vesicle growth and division. Such living systems exist in a state markedly distinct from conventional physical systems, and elucidating the fundamental differences between living and non-living matter is a critical step toward understanding the essence of living systems. However, contemporary living systems are highly complex, making it extremely challenging to directly analyze the distinctions between life and matter using current organisms. To overcome this, we have constructed a model system—a minimal cell—that captures the essential features of life. Our synthetic minimal cell is a vesicle-based system that integrates the following three functional modules: 1. Artificial metabolic system, 2. Information processing system, and 3. Self-reproduction system. Furthermore, by varying the types of membrane molecules and genetic polymers, we have constructed eight distinct minimal cell types. By comparing their growth rates (fitness), we are developing a system in which the dynamics of evolution due to competition among minimal cells can emerge. In this seminar, we will introduce our synthetic minimal cell research and examine the conditions required for sustained proliferation and evolution from the perspective of non-equilibrium dynamics and information thermodynamics. This approach aims to shed light on the physical origin of the fundamental distinction between life and non-life.
https://indico.ijs.si/event/2975/

Nandini Das: Peeping into dark matter scenarios - From freeze in to freeze out
2025-06-12 15:30 - 16:30 | https://zoom.us/j/3601731049?pwd=[REDACTED] (A/1-106 – Seminarska soba fizike (F5))
The existence of dark matter in the universe is an unavoidable fact while the nature of it still remains an unresolved mystery. We here try to explore the possibilities of having particle dark matter through different level of detection prospect. With an example from each models, we would try to sketch a brief overview towards freeze in and freeze out.
https://indico.ijs.si/event/2967/

Arnau Bas i Beneito: New methods to probe Standard Model Extensions via Proton Decay and Neutrino Masses
2025-06-13 11:00 - 12:00 | https://zoom.us/j/3601731049?pwd=[REDACTED] (C/2-X – F1 čajnica)
Baryon and lepton number are excellent low-energy symmetries of the Standard Model (SM) that tightly constrain the form of its extensions. In this paper we investigate the possibility that these accidental symmetries are violated in the deep UV, in such a way that one multiplet necessary for their violation lives at an intermediate energy scale M above the electroweak scale. We write down the simplest effective operators containing each multiplet that may couple linearly to the SM at the renormalisable level and estimate the dominant contribution of the underlying UV model to the pertinent operators in the SMEFT: the dimension-5 Weinberg operator and the baryon-number-violating operators up to dimension 7. Our results are upper bounds on the scale M for each multiplet–operator pair, derived from neutrino-oscillation data as well as prospective nucleon-decay searches. We also analyse the possibility that both processes are simultaneously explained within a natural UV model. In addition, we advocate that our framework provides a convenient and digestible way of organising the space of UV models that violate these symmetries.
https://indico.ijs.si/event/3005/

Misha Gorshteyn: Cabibbo unitarity: anomaly (dis)appears
2025-06-19 15:30 - 16:30 | https://zoom.us/j/3601731049?pwd=[REDACTED] (A/1-106 – Seminarska soba fizike (F5))
Unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix is one of the cornerstones of the Standard Model.
The unitarity constraint that involves the top-row matrix elements, $|V_{ud}|^2+|V_{us}|^2+|V_{ub}|^2=1$ is particularly
important because all elements are measured very precisely permitting a test at the 0.01% level. At this accuracy,
$V_{ub}sim10^{-3}$ is irrelevant, and the unitarity constraint reduces to the two-flavor Cabibbo unitarity pattern with a single
Cabibbo angle $theta_C$ and $V_{ud}=costheta_C$ and $V_{us}$. At present, a mild deficit is observed,
$|V_{ud}|^2+|V_{us}|^2=0.9985(7)$. As such, this deficit may suggest some new physics, but to make this claim all Standard
Model ingredients must be firmly under control. I review these ingredients across theory and experiment and review the most
recent developments.
https://indico.ijs.si/event/2861/

Tea Tušar (TBA)
2025-06-26 14:00 - 15:00 | A/1-106 – Seminarska soba fizike (F5) (Jamova)
https://indico.ijs.si/event/2978/

Martin Schmaltz: Hubble tension update
2025-07-03 11:00 - 12:00 | https://www.youtube.com/@astroFMF/streams (F4 – FMF)
This seminar will give an introduction to and status update of the Hubble tension, the 6 sigma discrepancy between the two most precise methods for measuring the expansion rate of our Universe. The most promising resolutions of the tension employ “early” new physics to modify the sound horizon, the standard ruler used in CMB and BAO based determinations of the expansion rate. A possibly related new piece of the puzzle might be the recent evidence for non-standard dark energy from the DESI experiment.
https://indico.ijs.si/event/3014/

Raquel Molina: Quark mass dependence of hadron resonances
2025-07-07 11:00 - 12:00 | https://zoom.us/j/3601731049?pwd=[REDACTED] (F1 tea room)
https://indico.ijs.si/event/2976/

David Kaplan: Shadow Matter
2025-07-10 11:00 - 12:00 | https://www.youtube.com/@astroFMF/streams (F2 – FMF)
I will review how one gets classical physics from quantum theories. Then I will show that there are quantum states of the field theories of general relativity and electromagnetism that we typically ignore, but have interesting phenomenological effects. These states amount to loosening the constraint equations in GR and EM. Doing so in GR sources non-dynamical parts of the metric which mimic a pressureless dust, with some odd features, and thus these effects may be the explanation as to why we think there is dark matter. The constraint in EM is Gauss’ Law, and turning it off mimics a charge density that does not respond to electric forces, but follows geodesics. I will briefly discuss the cosmological consequences of these new fields and potential studies.
https://indico.ijs.si/event/3015/

Fabio Staniscia (TBA)
2025-07-10 14:00 - 15:00 | A/1-106 – Seminarska soba fizike (F5) (Jamova)
https://indico.ijs.si/event/3006/

Lorenzo Ubaldi: Schwinger current in de Sitter
2025-07-25 16:00 - 17:00 | https://zoom.us/j/94950883072 (F1 – tea room)
We study classical background electric fields and the Schwinger effect in de Sitter space. We show that having a constant electric field in de Sitter requires the photon to have a tachyonic mass proportional to the Hubble scale. This has physical implications for the induced Schwinger current which affect its IR behaviour. To study this we recompute the Schwinger current in de Sitter space for charged fermions and minimally coupled scalars imposing a physically consistent renormalization condition. We find a finite and positive Schwinger current even in the massless limit. This is in contrast to previous calculations in the literature which found a negative IR divergence. We also obtain the first result of the Schwinger current for a non-minimally coupled scalar, including for a conformally coupled scalar which we find has very similar behaviour to the fermion current. Our results may have physical implications for both magnetogenesis and inflationary dark matter production.
https://indico.ijs.si/event/3030/

Basudeb Dasgupta: Probing Dark Matter with Low-Mass Black Holes
2025-09-04 15:30 - 16:30 | A/1-106 – Seminarska soba fizike (F5)
Heavy non-annihilating dark matter captured by neutron stars can trigger collapse into low-mass black holes, producing subsolar-mass mergers detectable by gravitational wave observatories. These events probe dark matter-nucleon interactions at cross-sections below the neutrino floor and dark matter masses from GeV to PeV. Existing LIGO/Virgo data already place strong bounds; future detections could reveal dark core collapse and explain anomalies like the missing pulsars near the Galactic Center. I will discuss how to distinguish low-mass black holes from neutron stars via gravitational wave signatures, and how this affects sensitivity to dark matter.
https://indico.ijs.si/event/2816/

Katarina Kokalj, "Newton black films"
2025-09-11 14:00 - 15:00 | A/1-106 – Seminarska soba fizike (F5) (Jamova)
https://indico.ijs.si/event/3050/

Damir Bečirević: Why the radiative decays of quarkonia are important
2025-09-18 15:30 - 16:30 | A/1-106 – Seminarska soba fizike (F5)
TBA
https://indico.ijs.si/event/3046/

Ryan Plestid: Detecting dark matter with a picogram detector
2025-09-25 15:30 - 16:30 | A/1-106 – Seminarska soba fizike (F5)
Dark matter direct detection is dominated by a landscape of macroscopic detectors. How then can quantum sensors, such as an atom interferometer compete? In this talk I will outline recent work on how large coherent enhancements amplify dark matter signals in an atom interferometer. All of the necessary theory is elementary quantum mechanics, and yet the role of N-enhancements is subtle, due to the many-branched nature of an atom intereferometer’s wave function.

Based on: 2402.03421 and 2509.13417
https://indico.ijs.si/event/3028/

Jose Espinosa: Surprises in Vacuum Decay
2025-09-30 15:00 - 16:00 | C/2-X – F1 čajnica
In the standard lore the decay of the false vacuum of a single-field potential is described by a semi-classical Euclidean bounce configuration that can be found using overshoot/undershoot algorithms, and whose action suppresses exponentially the decay rate. While this is generically correct, the vacuum decay structure can be far richer. In some cases there is no bounce and decay proceeds via the so-called pseudo-bounces. In the general case with bounce, there are 2n+1 bounces, with n ranging from 0 (the standard case) to ∞. Some of these decays occur via “antibounces” which have the wrong behavior for overshoot/undershoot algorithms, that can miss them. Bounce and antibounce configurations form n pairs connected by pseudo-bounces.
https://indico.ijs.si/event/3088/

Santiago Tanco: Bayesian tools for the LHC: a proof of concept in di-Higgs searches
2025-10-02 11:00 - 12:00 | A/1-106 – Seminarska soba fizike (F5)
Extracting reliable physical information from collider data requires a combination of mathematical, computational and statistical tools to model observed distributions, often with the help of powerful simulations. But when simulations cannot be fully trusted, data-driven approaches become indispensable. In this talk, I will present Bayesian tools that provide a flexible, data-driven method for unsupervised training on probabilistic models of collider observables, highlighting their advantages for parameter inference and uncertainty estimation. I will illustrate these points in the context of pp > hh > bbbb searches, where recent analyses use a variation of the widely used data-driven “ABCD method”. Within our framework, the ABCD method can be generalized and improved, especially when its assumptions are not exactly satisfied, leading to more robust background subtraction. Our approach is able to exploit correlations in multi-dimensional data by modelling kinematic variables and b-tagging scores at the event level. These results also show a way in which simulations can be used as guides for unsupervised estimation of the true data distributions. Based on 2402.08001 and ongoing research.
https://indico.ijs.si/event/3054/

Bhabani Tripathy: doubly heavy tetraquarks
2025-10-06 15:00 - 16:00 | F1 tea room
Doubly heavy tetraquarks
https://indico.ijs.si/event/3101/
