The Nearest Neighbors estimation of likelihood is implemented for the multivariate amplitude analysis of the cascades of particle decays. In this approach Monte Carlo simulated events that are used to describe data are assigned weights dependent on the parameters of the theoretical fitting model. Each of such weighted events is considered as contributing to N-dimensional probability density function (p.d.f.) in its neighborhood in the parameter space. No analytic p.d.f. or cpu-intensive re-generation of N-dimensional p.d.f. at each fit step are required. The method allows accurate accounting for reconstruction effects, demands modest cpu resources and can be effectively multi-threaded. General setup of the fit as well as toy example of the amplitude analysis of B-meson decays are demonstrated.

Being a spin-1 particle, the deuteron, when polarized, offers access to a wide range of interesting tensor observables. A quest for tensor asymmetries is at the heart of the spin physics with polarized deuterons at future colliders, and calls for frequent tensor polarization flips in storage rings or in deuterium targets.
Here we focus on the JEDI developed technique of the Fourier analysis of the horizontal polarization oscillations under continuous radiofrequency-driven spin flips. The generated in this way time-stamped oscillating helicity of stored particles paves the way to the nucleon/nucleus spin structure studies and to the search for the parity violation. Simultaneously, a whole set of tensor spin asymmetries, including the off-diagonal ones needed for searches for the T-violation beyond the Standard Model, will be produced.
A crucial ingredient is a long polarization lifetime, and we report the first analytic treatment of decoherence of the tensor polarization under continuous radiofrequency spin flips. Our principal conclusion is that at low- and intermediate-energy accelerators the deuteron polarization lifetime could be in the ballpark of several hours, making the oscillating polarization approach viable at the Nuclotron/NICA and HIAF.
We comment on a utility of the flattop spin-tensor dichroism via oscillations in the cross section of interaction of deuterons in the internal target as a monitor of the tensor polarization. Simultaneously, the dichroism effect can be used for measuring the spin precession frequences and as a comagnetometer to synchronize spin phases of colliding bunches in a collider.

Corrected: 11 August 2026 (Eq. (28) was revised; typos and grammar were corrected)

The experimental data collected by KEDR and BESIII collaborations at the energies below charm quark thresholds are compared with the massless QCD expressions for the \(e^+e^-\) annihilation R-ratio truncated at different orders of perturbation theory. The fits demonstrate the dependence of the extracted \(\alpha_s(M_Z)\) values on the orders of truncation of the corresponding approximations. The next-to-leading order, next-to-next-to-leading order and next-to-next-to-next-to-leading order fits of the combined KEDR data and BESIII data , truncated at the scale of mass of \(J/\Psi\) meson, give the following results \(\alpha_s(M_Z)=0.1151_{-0.0069}^{+0.0052}\), \(\alpha_s(M_Z)=0.1190_{-0.0081}^{+0.0064}\) and \(\alpha_s(M_Z)=0.1283_{-0.0075}^{+0.0028}\). The increasing tendency of fitted \(\alpha_s(M_Z)\) value is associated with the effects of not totally controlled within asymptotic perturbation theory expansions kinematical \(\pi^2\) contributions to R-ratio coefficients due to analytical continuation from the space-like to time-like energy regions. The applications of the fixed orders of perturbation theory expansions and careful treatment of the analytical continuation effects are commented.

Corrected:

28 July 2026 (changes have been made in Eqs. (12)–(14) and an expression has been added after them)

In 1960, the world’s first pulsed fast nuclear reactor (IBR) was created at JINR. The second-generation IBR-2 reactor has been in operation since 1984. An analysis of the distinctive characteristics of the IBR-type reactors is presented, the main one of which is related to the instabilities of power fluctuations. A description of the conceptual design of a third-generation NEPTUN reactor is proposed, which solves the problem of instabilities and opens up new possibilities for neutron beam research.

The Machine Learning (ML) approaches were applied to particle identification in the simulation of the Spin Physics Detector (SPD) at the NICA Collider. The results of the identification of muon tracks originating from charmonia decays and pion tracks in the intermediate momenta region (1.5–2.5 GeV/c) are presented. The obtained classifier accuracy is 77% while preserving 99% of muons and rejecting 48% of pions. The efficiency of developed binary classifier is demonstrated through background suppression in J/ψ → µµ decays.

The conformational behavior of the amyloid-β42 (Aβ42) peptide is strongly influenced by the physical state of its surrounding lipid environment. The effect of temperature on the Aβ42 structure within dipalmitoylphosphatidylcholine (DPPC) bilayers was investigated using circular dichroism (CD), Raman spectroscopy, and molecular dynamics (MD) simulations. The study examined two thermal phases: room temperature (RT =∼ (25±2)◦C), corresponding to the gel phase of DPPC, and (48±2)◦C, representing the fluid phase above the lipid transition temperature. The CD spectroscopy measurements indicated a clear temperature-dependent structural transition of the peptide. At RT, Aβ42 exhibited a conformation enriched in β structures, while at (48±2)◦C, the spectra revealed a notable increase in α-helical content, reflecting enhanced backbone organization under fluid-phase conditions. Raman spectral analysis supported this trend by demonstrating an increased contribution of α-helical components accompanied by a reduction in β-strand features upon heating. Minor variations in lipid vibrational markers further suggested greater acyl-chain flexibility and bilayer fluidity in the high-temperature state. Furthermore, MD simulations revealed enhanced α-helical content and deeper peptide insertion within the disordered bilayer compared with the ordered gel phase. The findings from experimental and computational investigations demonstrate that membrane fluidization above the DPPC phase transition favors α-helical stabilization of Aβ42, emphasizing temperature as a key parameter governing peptide–lipid conformational equilibria. The results obtained provide a fundamental framework for understanding how thermal conditions modulate amyloid-membrane interactions, which is essential for elucidating the early molecular events associated with amyloid-related pathologies.