Within classical electrodynamics, the problem of the existence or non-existence of massless charges is commonly associated with the problem of radiation reaction. Here, the relativistic system of two massless charged particles is considered within the Staruszkiewicz model, in which radiation reaction is neglected. The model is formulated in the Hamiltonian form with constraints. The system is invariant with respect to 15-parameter conformal group. The corresponding conserved canonical generators and the relativistic Laplace–Runge–Lenz vector imply the superintegrability of the system. The trajectory of the unbounded relative motion is hyperbolic, as in the non-relativistic Kepler problem. Surprisingly, particle world lines turn out to be lightlike straight rays, as if charges are switched off. Abstract Published by the Jagiellonian University 2026 authors
This paper proposes a new simple memristive chaotic system (MCS) containing an exponential term, a constant term, and a memristor-based nonlinear term. The system has dissipative feature and only one equilibrium. Its parameter-relied complex dynamics are comprehensive studied and the chaos with large parameter regions, multiple bifurcations, and large-scale amplitude modulation are revealed. The proposed system can realize the transition from stability to periodicity via Hopf bifurcation and generate chaos via period-doubling bifurcation with the increase or decrease of multiple parameters. The boundaries of chaotic attractors and the oscillation amplitudes of variables expand over a large-scale range as the parameter values continuously increase, indicating the emergence of large-scale amplitude modulation in the system. Moreover, the fixed-time synchronization (FxTS) problem is studied and the corresponding FxTS conditions are obtained by applying slide mode controller with the designed power reaching law. Both the theoretical derivation and numerical simulation consistently demonstrate the effectiveness of the obtained results. Abstract Published by the Jagiellonian University 2026 authors
This study explores the elastic scattering of charged hadronic system through a new approximation scheme for the effective potential. The Phase Function Method (PFM) is employed to examine the scattering phase shifts in the \(p\)–He\(^{3}\) system, where a modified Kratzer potential is enhanced by electromagnetic interactions and spin–orbit coupling. A six-parameter potential model is developed and optimized to match the calculated scattering phase shifts, differential cross-sections, and proton analyzing power curves with experimental data for the \(p\)–He\(^{3}\) system. The results show strong consistency with experimental measurements and previous theoretical predictions, affirming the accuracy and utility of the proposed method in analyzing scattering phenomena within this system. Abstract Published by the Jagiellonian University 2026 authors
The wounded nucleon model was invented to account for the multiplicity of particles produced in nucleus-nucleus collisions. As such, it emphasizes the features of particle production along the collision axis. It contains, however, another important aspect, which is the main focus of this note, that the early stages of high-energy nuclear collisions are determined by the locations of the wounded nucleons in the transverse plane. Thanks to the high-precision data of the LHC, this may, in return, be used to infer fine nuclear structure aspects of the colliding nuclei.
The study of the process of particle creation in high-energy nucleon-nucleon and nucleus-nucleus collisions heavily relies on the pseudorapidity distribution (PD) of charged particles. Several theoretical theories and concepts may frequently be tested using the multiplicity distributions (MD) and PD of final-state particles. In this work, we have utilized PD to investigate potential processes that might produce the fast target protons (FTP) released from the interactions of 84Kr with emulsion at 1 A GeV. In order to examine the properties of the FTP emitted system for various targets (such as AgBr, CNO, and Em) of the nuclear emulsion detector (NED), the angular distribution (AD) and PD of the generated FTP were examined.
The Verwey phase transition in magnetite (Fe3O4) exhibits a variety of phenomena that are typical of phase transformations, but in a particularly striking and pronounced form. As these phenomena and their peculiarities can be easily overlooked in the observation of other phase transitions, observing the Verwey transition, where these peculiarities are clearly visible, can draw attention to them in other phase transition studies. Important and acute phenomena showing these peculiarities include: strong dependence on doping, non-stoichiometry and defects, which can even cause a change in the character of the phase transition; the complexity of the transition, which can be predicted and observed over a wide temperature range; strong electron-electron and electron-phonon coupling; and the ability to manipulate the electronic system using a magnetic field, hydrostatic pressure or uniaxial pressure. Since these properties are typical of all solids yet accentuated in this compound and the transition is easily observable using standard and sophisticated techniques, studying it may improve our understanding of any phase transformation.
In this article, ultraperipheral collisions of nuclei are discussed with focus on the probes of nuclear structure. Calculations for the open charm production in UPC collisions of PbPb at the LHC are described and compared with the experimental data from the CMS experiment.
In this manuscript, we show some interesting aspects of physics of interface. These are related to the phenomena occurring in the interior of neutron stars.
We describe the physics program at the Relativistic Heavy Ion Collider (RHIC) with forward protons measured in the Roman Pot system. The program started as a standalone PP2PP experiment with a goal of measuring of proton-proton elastic scattering. The PP2PP experiment took data at RHIC as a dedicated experiment at the beginning of RHIC operations. To expand the physics program to include non-elastic channels tral Production (CP), and Single Diffraction Dissociation (SD), the experiment with its equipment was merged with the STAR experiment at RHIC. This allowed for a more comprehensive diffractive physics program with measured forward protons. The expanded program, which included both elastic and inelastic proton-proton scattering, became part of the physics program and operations of the STAR experiment. The results obtained by both programs are described here. Given that proton beams at RHIC were polarized, the results include spin dependence in proton-proton elastic scattering.
Femtoscopy, historically associated with Hanbury-Brown-Twiss (HBT) interferometry, has evolved into a precision tool for investigating the spacetime structure of particle-emitting sources created in high-energy collisions. While the term HBT is often used, it captures only a subset of the broader class of femtoscopic correlation techniques based on quantum-statistical correlations. This review provides a systematic overview of femtoscopic measurements across a broad range of collision energies and system sizes. We explore the "sizes" of homogeneity regions through detailed energy scans, spanning from the low-energy regime of HADES to the highest energies of the RHIC Beam Energy Scan and the LHC. We examine the system-size dependence of these regions, including the intermediate regime of p-Pb collisions at the LHC, which serves as a bridge between elementary p-p and dense A-A systems, while highlighting the breakdown of universal multiplicity scaling due to initial-state geometric effects. Furthermore, we discuss non-identical particle correlations, such as pi-K, as a unique probe of relative space-time emission asymmetries, providing independent evidence for collective transverse expansion. The review also addresses "interaction femtoscopy" exploiting the sensitivity of correlation functions to final-state interactions in order to extract scattering parameters for (anti)protons, Lambda hyperons, and light nuclei. These measurements impose important constraints on hyperon-nucleon and three-body interactions, supplying essential input for chiral effective field theory and the equation of state of dense nuclear matter, with significant implications for the internal structure of neutron stars.
Potential and corresponding electric and magnetic fields of a moving point-like charge are computed in several ways. The subtle limit of the charge velocity equal to the speed of light is taken either in the final formulas or in the equation of motion. The results are discussed.
In this study, we present an improved formulation for calculating (p, n) reaction cross sections at a proton energy of 12.4 MeV. This new approach is based on updated experimental data (EXFOR 2026), a revised compilation of non-elastic cross sections using the TALYS nuclear reaction code, and a re-evaluation of the empirical adjustment parameters. The proposed model builds upon the work of Broeders and Konobeyev (2008) and integrates key theoretical elements of the compound nucleus regime, including the semiempirical mass formula and the statistical evaporation model. Comparisons with TALYS calculations, which include both statistical and pre-equilibrium contributions, demonstrate the validity of our approach at 12.4 MeV, where compound nucleus mechanisms dominate. The revised six-parameter formulation demonstrates excellent agreement with the latest experimental data and yields significantly reduced values for the statistical deviation metrics Sigma and chi 2. This work contributes to the refinement of nuclear reaction models and provides a reliable tool for cross-section prediction in applied and fundamental nuclear science.
Exploring the QCD phase diagram through relativistic heavy-ion collisions is a primary goal of modern nuclear physics. This contribution focuses on fluctuations and correlations of conserved charges specifically net-baryon and net-charge cumulants as sensitive probes of the phase structure and the QCD critical point. We discuss recent theoretical and experimental advancements, highlighting constraints from lattice QCD and new results from the RHIC Beam Energy Scan program. Key challenges in theory-to-experiment comparisons at high baryon density are discussed, alongside the systematic requirements for meaningful physical interpretation. Finally, we identify open issues and outline the discovery potential of future low-energy experiments, such as CBM, in resolving the high-density regime of the phase diagram.
