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FORTE Science Day - 2nd Edition
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Europe/Prague
Dvorak Lecture Hall (Institute of Physics)
Dvorak Lecture Hall
Institute of Physics
Pod Vodárenskou věží 2531/3, 182 00 Praha 8
Description
This event, tailored for students and early-career researchers who are encouraged to join, will feature accessible talks from the FORTE project and a networking lunch to connect with fellow researchers.
Lunch will be provided in the form of sandwiches.
To help us prepare the catering, you are kindly asked to register by the 10th of June.
Zoom link: https://cesnet.zoom.us/j/97836295240?pwd=2jxn8UXH5he6yM5188q4xfoZyIYONa.1
Details on the FORTE Science Day - First Edition can be found here
Participants
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IntroductionSpeaker: Dr Constantinos Skordis (CEICO, Institute of Physics, Czech Academy of Sciences)
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ATLAS: Giant Detectors to Ask Tiny Questions
What are the smallest building blocks of matter, and how can we study them with one of the largest scientific instruments ever built? This talk introduces selected physics activities pursued under the FORTE project within the ATLAS experiment at CERN. We will look at how ATLAS uses record-breaking LHC data to test our understanding of nature, search for signs of new particles, study the behaviour of the top and beauty quarks, explore the hot matter created in heavy-ion collisions, and use modern machine-learning methods to improve particle measurements. The examples range from precision studies of ordinary matter to searches for rare and unexpected phenomena, showing how giant detectors help us ask, and sometimes answer, tiny but fundamental questions.
Speaker: Dr Martin Rybar (Charles University (CZ)) -
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Measurements of CP Violation in Penguin-Dominated B Decays at Belle II
Understanding the matter–antimatter asymmetry of the universe requires precise measurements of CP violation in rare B meson decays. Penguin-dominated decays, proceeding through quantum loop diagrams, are uniquely sensitive to potential New Physics that could modify the expected CP asymmetry. We present a study of B⁰ → ωK⁰_s at Belle II, establishing a full analysis framework using Monte Carlo simulation. Our sensitivity projections show ~3.8σ evidence for mixing-induced CP violation with significantly improved precision over previous experiments. Results on real data are forthcoming.
Speaker: Shubhangi Maurya (Charles University, Prague) -
10:25
Coffee break
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Multimessenger Astrophysics and the Phenomenology of Ultra-High-Energy Cosmic Rays
Cosmic rays are the most energetic particles observed in the Universe.
Although extremely rare, a handful of events with energies exceeding
$10^{20}\,\mathrm{eV}$ have been detected. This corresponds to about
$16\,\mathrm{J}1$ concentrated in a single particle and to an equivalent
thermal energy scale of approximately $10^{24}\,\mathrm{K}$, comparable
to that of the Universe roughly $10^{-29}\,\mathrm{s}$ after the Big
Bang. We now know that cosmic rays have a surprisingly continuous,
almost featureless non-thermal energy spectrum spanning over ten orders
of magnitude. Their study has led to the discovery of several particles
and to the birth of particle physics. Even today, particle physics and
cosmic-ray physics remain closely connected and continue to benefit from
one another. Despite major advances, fundamental questions remain
unanswered, particularly regarding the astrophysical origin of cosmic
rays and the mechanisms that can accelerate these particles to such
extreme energies. Multimessenger astrophysics is the most promising path
towards answering these questions. In this talk, I will briefly guide
you through our understanding of cosmic rays over time. Along this
timeline, I will present a set of selected contributions from our group
to address several still-open questions.Speaker: Dr Eva Maria Martins Dos Santos (Czech Academy of Sciences (CZ)) -
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Calibration of PMTs for FAST telescopes
This work presents the characterization and gain calibration of large-area hemispherical photomultiplier tubes (PMTs) utilized in the FAST telescope for ultra-high-energy cosmic ray detection. Specifically, the Hamamatsu R5912-03 and the Hamamatsu R14688 models were thoroughly tested inside a climate chamber across a temperature range of -20°C to +40°C. The gain calibration was performed using a multi-photon measurement method. Beyond standard voltage and temperature dependence fitting, a next phase of the study focused on the spatial uniformity of the photocathode response. This uniformity is significantly influenced by the Earth's magnetic field.
Furthermore, comparing controlled laboratory benchmarks with actual on-site deployments at the Pierre Auger Observatory revealed systematic shifts in performance. These variations are driven by local magnetic field differences and ambient environmental cycles at the observation sites. The best positionn of PMTs were set to minimize the impact of the magnetic field.
Accounting for these environmental and magnetic field dependencies proved essential for maintaining the long-term data accuracy of the FAST telescope array.Speaker: Vlastimil Jilek -
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JUNO experiment and liquid scintillator nonlinearity measurement
JUNO, the Jiangmen Underground Neutrino Observatory, is a 20 kton liquid scintillator neutrino oscillation experiment in southern China. The experiment started taking data in 2025.
The experiment has many goals and ambitions e.g. determining the neutrino mass hierarchy, measurement of the oscillation parameters with unprecedent precision. In its rich physics program precise determining energy response of the liquid scintillator is crucial.
The amount of light emitted from the scintillator is not exactly linearly proportional to the energy deposited in it, the light yield behaves nonlinearly. This is due to the Birk’s quenching effect and also, for higher energies, due to the Cherenkov radiation.This work introduces the JUNO experiment, its first results and focuses on the observation of nonlinear response from the liquid scintillator using Compton scattering and on the extraction of the Birk’s quenching parameter kB
Speaker: Tomáš Tměj (Charles University) -
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The Hunt for Observables in String Models
I will discuss how axions can be used as a probe of string
theory via cosmological and terrestrial experiments. The focus will
largely be on gravitational wave production via the spectator mechanism
and how quantum gravity constrains the possibilities. I will also
discuss how the QCD axion can imply a bound the compactification volume
and non-perturbative particle production axions in the early universe.Speaker: Dr Jacob Leedom (FZU) -
12:30
Lunch
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ALICE Physics @ FORTE
In this talk, an overview of selected physics topics and recent results from the ALICE Collaboration will be presented, with a particular focus on measurements pursued within the FORTE project. Specifically, results on strange-baryon enhancement in jets in Pb–Pb collisions will be discussed as a probe of the properties of the quark–gluon plasma (QGP). Measurements related to jet quenching and anisotropic flow in O–O collisions will be presented to explore the physics of small collision systems. In addition, recent studies of ultra-peripheral collisions will be highlighted.
Speaker: Katarina Krizkova Gajdosova (Czech Technical University in Prague (CZ)) -
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Search for jet quenching in OO collisions with the Event Activity dependence of hadron-jet correlations
This analysis searches for jet-quenching effects in OO collisions at $\sqrt{s_{\mathrm{NN}}}=5.36$ TeV using semi-inclusive hadron-jet correlations. Event activity (EA) is characterised primarily by FT0, while ZDC observables are used to test whether the EA selection retains sensitivity to collision geometry. A clear non-linear correlation between FT0 and ZDC signals indicates that FT0-based EA preserves a strong geometric component.
The main observable is the recoil-jet distribution measured relative to a high-$p_{\mathrm{T}}$ charged trigger hadron as a function of EA. The semi-inclusive approach is insensitive to CNM effects and centrality bias, providing a cleaner probe of possible parton energy loss in the OO system. Within the current sensitivity, no significant variation of the recoil-jet spectrum with EA is observed.
Speaker: Artem Kotliarov (Czech Academy of Sciences (CZ)) -
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Symbolic Regression for Fast Cosmological Modeling
Modern cosmology requires repeated evaluations of complex theoretical
predictions for inference, forecasts, and tests of physics beyond ΛCDM.
Symbolic regression provides a fast and accurate way to build surrogate
models while retaining compact analytical expressions that are
transparent, interpretable, and easy to implement.
I will present applications of symbolic regression to cosmological
observables, including CMB lensing, temperature, and polarization
spectra in extended ΛCDM models with massive neutrinos and evolving dark
energy. I will also discuss its use for matter power spectra in
non-standard dark matter scenarios, such as the Generalized Dark Matter
framework. These examples show that symbolic regression can be a
practical tool for accelerating cosmological analyses while keeping the
resulting models lightweight and analytically accessible.Speaker: Mr David Vokrouhlicky (FZU) -
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Quantum Ghost
Ghosts frequently emerge in alternative theories of gravity. They are degrees of freedom with wrong-sign kinetic terms, and the common lore is that ghostly degrees of freedom lead to dynamical instabilities, so-called runaways. In quantum mechanics, ghosts are commonly believed to lack physically relevant quantum descriptions. However, ghosts can be benign both classically and quantum mechanically. This talk will briefly cover some recent advancements in stability of classical ghostly systems, and then present a fully physical quantum mechanical description of a ghost. In particular, we define the vacuum state and demonstrate the absence of quantum runaway behavior.
Speaker: Mr Atabak Jalali (FZU) -
15:20
Coffee break
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Angstrom coefficient calculation using wide field stellar photometry
The FRAM (F/Photometric Robotic Atmospheric Monitor) telescopes
are small robotic instruments deployed at astroparticle physics
observatories for continuous atmospheric monitoring using wide-field
stellar photometry. At the Cherenkov Telescope Array Observatory (CTAO),
FRAM measures the vertical aerosol optical depth (VAOD) at optical
wavelengths.We extend the original single $B$-filter (440~nm) method to simultaneous
measurements in $B$, $V$ (540~nm), and $R$ (620~nm) using Gaia~DR3
synthetic photometry, enabling the determination of the Ångström
coefficient --- which describes how aerosol extinction varies with
wavelength. We derive the Ångström coefficient at three CTAO sites over
2021--2022 and validate the results against independent AERONET
sun-photometer measurements at La Palma, where both
instruments independently recover the same two aerosol populations
corresponding to episodic Saharan dust intrusions and clean maritime
background conditions. This agreement between two completely independent
instruments operating on different physical principles provides
confidence in the FRAM method for nighttime aerosol characterisation
at the CTAO sites.Speaker: Shefali Negi -
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Testing Lepton Flavour Universality with Rare Kaon Decays at NA62
The NA62 experiment at CERN is a fixed-target experiment located in the North Area of the SPS accelerator complex.
Its primary goal is the precise measurement of the ultra-rare kaon decay K+→π+ννˉ,
one of the most sensitive probes of physics beyond the Standard Model.During Run 1 and the ongoing Run 2 data-taking periods, NA62 has collected an unprecedented sample of charged kaon decays,
enabling measurements with very small statistical uncertainties. In addition to its flagship programme, the experiment provides unique opportunities
for precision studies of rare kaon decays involving charged leptons, such as K+→π+ℓ+ℓ− decays.The Prague NA62 group is pursuing a precision measurement of these decay modes with the ultimate goal of testing Lepton Flavour Universality.
This talk will present the current status of the analysis and discuss the expected sensitivity and projected results using the full NA62 data set.Speaker: Marjan Cirkovic (Charles University (CZ))
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