The \(B \rightarrow K\tau \ell \) decays (where \(\ell =e,\mu \)) are not allowed in the Standard Model (SM) at the tree level due to lepton flavor violation (LFV). In some New Physics (NP) models, their branching fractions are within the reach of the current experimental sensitivities. The Belle and Belle II experiments provide ideal conditions for their search. We used the basic kinematic constraints of the experiments to reconstruct them. A multivariate classifier score is used to model the signal and background. For the estimation of statistical upper limits (ULs), the Bayesian approach is used. To validate the analysis method, two control channel modes are used. Abstract Published by the Jagiellonian University 2026 authors
An overview of charm-quark hadronisation within the PYTHIA/Angantyr model is provided. The improvements to the junction formation and fragmentation mechanisms in the context of charm-quark hadronisation are discussed. We discuss these changes in the context of the recently developed global colour reconnection mechanism, which is based on the QCD-inspired colour reconnection model. We show the enhancement in \({\mit \Lambda }_c\) baryon yield in \(\pp \) and \(\pPb \) collisions at the LHC at \(\sqrt {s_{NN}} = 5.02\) TeV collision energy using the PYTHIA/Angantyr model. Abstract Published by the Jagiellonian University 2026 authors
A successor to the PACIFIC front-end ASIC, currently used in the LHCb Scintillating Fibre (SciFi) Tracker, is being developed for the second foreseen upgrade of the LHCb experiment. The new ASIC, referred to as PACIFIC++, is implemented in 65 nm CMOS technology and extends the architecture of the existing PACIFIC, designed in 130 nm CMOS technology. The new design introduces a 10-bit ADC and a 6-bit TDC measurement in each channel, together with on-chip clustering. The PACIFIC++ is proposed for the readout of the Mighty SciFi Tracker and Magnet Station detectors in the LHCb Upgrade II. An 8-channel prototype version of PACIFIC++, called PACIFIC+8, including all key functionalities, is currently being prepared for submission. This paper discusses the PACIFIC++ architecture and its current state of development. Abstract Published by the Jagiellonian University 2026 authors
An intermediate 48 V to 11 V DC/DC conversion stage, located in Patch Panel 2 (PP2), constitutes a key element of the power delivery chain for the ATLAS Inner Tracker (ITk) Strip detector. The design, based on commercial off-the-shelf components, meets the detector constraints and radiation tolerance requirements. Pre-production DC/DC boards demonstrate efficiencies above 81% across the full load range and low output noise, confirming the robustness of the PP2 system. Abstract Published by the Jagiellonian University 2026 authors
Studies of the internal structure of hadrons have been a main focus in particle physics since perturbative Quantum Chromodynamics (p-QCD) was established as the theory of the strong interaction. While the constituent quark model provided a successful framework for the investigation of many hadrons, recent decades have unveiled exotic states that defy simple classification. An example is the \(X(6900)\) resonance, identified in the di-\(J/\psi \) mass spectrum by LHCb, ATLAS, and CMS. As a tetraquark composed of \(c\bar {c}c\bar {c}\), its existence confirms the possibility of such multi-quark states. Its fundamental nature — whether it is a compact diquark–antidiquark entity or a diffuse molecule of two charmonia — remains an open question. We propose a study for the exclusive \(\gamma \gamma \to X(6900)\) process, accessible in ultraperipheral heavy-ion collisions (UPCs), which serves as a clean probe to differentiate between these inner structures. In this work, we calculate the respective two-photon decay width, \({\mit \Gamma }_{\gamma \gamma }\), using a leading-order Non-Relativistic QCD (NRQCD) framework. The long-distance matrix elements are determined from the wave functions at origin obtained in an extended relativized quark model. For the \(X(6900)\) as a radially excited (\(2s\)) compact state, we predict sizable widths of \({\mit \Gamma }_{\gamma \gamma }(2^{++}_{2s}) \approx 0.22\) keV and \({\mit \Gamma }_{\gamma \gamma }(0^{++}_{2s}) \approx 0.15\)–0.69 keV. These values are significantly larger than expected for a molecular state, providing a clear experimental discriminant. Abstract Published by the Jagiellonian University 2026 authors
The anomalous magnetic moment of the muon is one of the promising sectors for probing New Physics. Recent results from \(g-2\) experiments indicate a possible deviation of about \(5\sigma \) from the Standard Model prediction. The MUonE experiment was designed to precisely measure the hadronic contribution to the muon anomalous magnetic moment, which could increase the significance to at least \(7\sigma \) and thereby confirm potential discovery. Several crucial milestones have already been achieved by the MUonE project, and the results of the ongoing 2025 test run analysis will serve as the foundation for the full-scale 40 station proposal to be implemented after the LHC Long Shutdown 3. However, classical event reconstruction will face a significant challenge due to combinatorial scaling in this final configuration. To address these challenges, the use of Graph Neural Networks (GNNs) is proposed for the pattern recognition stage, as they offer the flexibility to process irregular geometries while maintaining the low latency required for a trigger. This allows for robust track reconstruction even in scenarios where detector hits may be missing, ensuring accurate performance under imperfect or incomplete data conditions. Abstract Published by the Jagiellonian University 2026 authors
Excited states of the \(^{207-213}\mathrm {Ac}\) nuclei were studied by employing fusion–evaporation reactions at the RITU and MARA separators of the Accelerator Laboratory of the University of Jyväskylä, Finland. In three of the four conducted experiments prompt \(\gamma \)-ray transitions were measured by employing the JUROGAM3 spectrometer, while the fourth experiment focused on delayed spectroscopy of \(^{207}\mathrm {Ac}\). Level schemes were established for odd-\(A\) isotopes, and those are compared to the systematics set by nearby astatine and francium nuclei, as well as to the excited states of the respective even–even isotone cores. Abstract Published by the Jagiellonian University 2026 authors
The \(\alpha \)-transfer and breakup channels in \(^7\mathrm {Be}+^{12}\)C at 35 MeV are studied. The total cross sections from \(\alpha \)-transfer, populating different states of \(^{16}\)O are obtained. This work also presents the first exclusive breakup measurement of \(^7\)Be. In contrast to earlier works, the results show a significant contribution of breakup. Abstract Published by the Jagiellonian University 2026 authors
There is an ongoing debate regarding the structure of the Cd isotopes, with the traditional interpretation of multiphonon vibrational states confronted with a recent suggestion that they possess multiple shape coexistence. In order to settle this debate, detailed studies are being pursued that include Coulomb excitation with multiple reaction partners and high-statistics \(\beta \)-decay measurements to provide high-precision spectroscopic data. We report results from very recent \(\beta \)-decay studies performed with the GRIFFIN \(\gamma \)-ray spectrometer on \(^{110,112,116}\mathrm {Cd}\) that confirm some of the previous \(\gamma \)-ray placements, bring others into question, and observe new transitions from states assigned to low-lying bands. Abstract Published by the Jagiellonian University 2026 authors
The discovery of gravitational lensing marked a significant milestone in observational astronomy. Massive galaxy surveys, combined with dedicated search strategies, have resulted in hundreds of known strong lensing systems. Consequently, this phenomenon is increasingly seen as a crucial tool in cosmology and fundamental physics. This article reviews selected developments in this field. Abstract Published by the Jagiellonian University 2026 authors
Leptogenesis is an attractive explanation for the observed baryon asymmetry of our Universe. In these proceedings, we study a framework where thermal leptogenesis occurs during a period of a first-order phase transition (FOPT). Right-handed neutrinos (RHNs) remain massless until bubble nucleation. Their abrupt mass generation leads to rapid decoupling and modifies the usual washout dynamics. Compared to standard thermal leptogenesis, where successful asymmetry requires masses above a certain scale, we find that bubble dynamics can dramatically reduce this scale and also study associated gravitational wave signals observable at terrestrial interferometers. Abstract Published by the Jagiellonian University 2026 authors
I cover usually omitted essentials from more than 43 years of my own experience in the domain of precision Monte Carlo programs development. I was not working alone, my work was a continuation of earlier efforts. For example, Stanisław Jadach’s achievements before 1981 were essential. I was working with him and B.F.L. Ward over most of these years. Also, monumental projects of Bryan Lynn, Robin Stuart, Dima Bardin, and Wolfgang Hollik in the domain of precision physics need to be mentioned, because they affected my work. This is a challenging call for me! Usually, we were publishing our own projects, and the following incomplete lists of methodology domains and projects were left aside in references, appendices, and private notes: (i) phase space: symmetries, (ii) matrix element preparation \(\to \) factorizations, (iii) program and development process design, (iv) testing strategies, (v) user interaction, (vi) software tools, (vii) partners and competitors. The work started on the basis of previous efforts which can be listed following names of the programs: (i) FOWL, (ii) GENRAP, (iii) Mustraal, (iv) Koralb, (v) Lesko, (vi) TAUOLA, (vii) KORALZ, (viii) LUMLOG, (ix) OLDBAB, (x) BHLUMI, (xi) BHWIDE, and (xii) KKMC. I will focus on some of these points. Others, hopefully, are sufficiently well covered in other papers. In particular, I do not need to cover exponentiation, see contribution to the proceedings by W. Placzek and talk of B.F.L. Ward. Developments took years and did not follow a straight line; that is why there are inevitable simplifications and biases in my presentation. Also, a review of the essential literature could not be completed. Abstract Published by the Jagiellonian University 2026 authors
Excited states of the triaxially deformed \(^{105}\)Pd have been studied. New rotational bands were identified and their configurations were determined. Some previously known bands have been extended to higher energies and spins. The main aim of this work was to search for the two-phonon wobbling band in addition to the already known one-phonon band. However, a comparison of the experimental data and the theoretical calculations revealed no evidence of a two-phonon wobbling band in \(^{105}\)Pd. Abstract Published by the Jagiellonian University 2026 authors
Properties of low-lying states in \(^{100}\)Zr were studied using the GRIFFIN spectrometer at TRIUMF following the \(\beta \) decay of \(^{100}\mathrm {Y}\). Using \(\gamma \)–\(\gamma \) angular correlations, level spins were confirmed and E2/M1 mixing ratios determined with improved precision. Applicability of a two-state mixing model to the observed structures in \(^{100}\mathrm {Zr}\) is explored. Abstract Published by the Jagiellonian University 2026 authors
We present studies on two Silicon Carbide (SiC) detectors for applications as dosimeters, micro-dosimeters, and beam-tagging devices, including detailed detector characterization, optimization of the associated electronics, and a performance comparison with conventional silicon-based detectors. Furthermore, preliminary device-level simulations carried out with Sentaurus are discussed to support the experimental results. The combined experimental and simulation studies demonstrate the potential of SiC as a promising alternative to silicon for radiation detection, particularly in environments where high radiation tolerance and fast response are required. Within this framework, the SAMOTHRACE ecosystem, in collaboration with CHIMERA, is working toward the development of a 10 \(\mu \)m thick SiC detector for dosimetry and micro-dosimetry, as well as a 100 \(\mu \)m thick device for beam-tagging applications. Abstract Published by the Jagiellonian University 2026 authors
We present the results of our calculation of the nuclear matrix element for the \(2\nu \beta \beta \) decay \(^{48}\mathrm {Ca} \rightarrow {^{48}\mathrm {Ti}}\), performed using a post-Hartree–Fock (HF) Density Functional Theory-based No-Core Configuration-Interaction (DFT-NCCI) framework developed by our group. The preliminary value we have obtained for the nuclear matrix element describing this process, \(|\mathcal {M}^{2\nu }| = 0.056(6)\) MeV\(^{-1}\), is in excellent agreement with the results of the shell-model study by Horoi et al. , which yielded 0.054 (0.064) MeV\(^{-1}\) for the GXPF1A (GXPF1) interactions, respectively. It is also in reasonable agreement with the most recent experimental estimate from the review by Barabash, which is 0.068(6) MeV\(^{-1}\), assuming a quenching factor \(qg_{\mathrm {A}} \approx 1\). The consistency of our prediction with the shell-model results strengthens our confidence in the nuclear modeling of this second-order, extremely rare process, which is of paramount importance for the further modeling of the \(0\nu \beta \beta \) decay. Abstract Published by the Jagiellonian University 2026 authors
Neutron capture reactions in high-temperature environments play a vital role in our understanding of the age of the universe, as well as the function of nucleosynthesis in the creation of the heavy elements. In general, the temperatures characterising these reactions are variable and can be split into two separate processes: the slow (s) and rapid (r) neutron capture processes. In this work, thermal effects are introduced at the initialisation of the wave-packet with an implementation of the time-dependent coupled channels wave-packet (TDCCWP) method. The agreement of this method with the already accepted CCFULL method is explored for the \(n+^{186}\mathrm {Os}\) reaction. Then, a comparison of thermally-dependent cross sections are made, where a decrease in the cross section is found for an increasing temperature, along with a decrease of \(19\%\) in the reaction rate when a temperature-dependent cross section is used. Abstract Published by the Jagiellonian University 2026 authors
Sterile neutrinos are promising candidates for dark matter, particularly in addressing small-scale challenges of the \({\mit \Lambda }\)CDM model. These particles are radiatively unstable, decaying into active neutrinos and photons, thereby injecting energy into the intergalactic medium (IGM) during the cosmic dawn. The energy injection can alter the temperature and ionization history of IGM, impacting the global 21 cm absorption signal predicted by standard cosmological models. Using the observed 21 cm signal from the EDGES Collaboration, we derive constraints on the sterile neutrino lifetime and their mixing angle with active neutrinos. Our bounds, obtained without assuming non-standard cooling mechanisms or additional radio backgrounds, are compared with the existing astrophysical limits, such as those from X-ray observations. For sterile neutrino masses between 2 keV and 50 keV, the lifetime is constrained to be greater than \(8.3 \times 10^{27}\) s to \(9.4 \times 10^{25}\) s for a 21 cm brightness temperature of \( -150 \) mK at \( z=17.2\). These results provide model-independent probes of sterile neutrino parameters relevant to dark-matter phenomenology. Abstract Published by the Jagiellonian University 2026 authors
The determination of the neutron skin thickness of \(^{208}\mathrm {Pb}\) from the PREX-II measurement of the parity-violating asymmetry \(A_{\mathrm {PV}}\) has generated considerable discussion within the nuclear physics community, revealing notable discrepancies with previous experimental results and theoretical predictions. PREX also reported a beam-normal single-spin asymmetry \(A_n\) for \(^{208}\mathrm {Pb}\), a key background to \(A_{\mathrm {PV}}\), that deviates from contemporary calculations — a discrepancy now known as the PREX anomaly. We present a new measurement of \(A_n\) in elastic electron scattering from natural lead performed at MAMI and discuss its implications for solving the PREX anomaly. We also outline the concept of the forthcoming Mainz Radius EXperiment (MREX) at MESA, designed to deliver an independent measurement of \(A_{\mathrm {PV}}\) in \(^{208}\mathrm {Pb}\) with twice the precision of PREX-II. Abstract Published by the Jagiellonian University 2026 authors
A Fourier parametrization of nuclear shapes and the macroscopic–microscopic method are used to evaluate the potential energy surfaces (PES) of nuclei in a 4-dimensional deformation space. The effect of different orientations in space of the nucleus is taken into account when deformations higher than quadrupole are considered. The effect on the PES of exact solving the pairing eigenproblem is also studied. Abstract Published by the Jagiellonian University 2026 authors
