Physics

We calculate three-loop photon spectral density in QED with N different species of electrons. The obtained results were expressed in terms of iterated integrals, which can be either reduced to Goncharov’s polylogarithms or written in terms of one-fold integrals of harmonic polylogarithms and complete elliptic integrals. In addition, we provide threshold and high-energy asymptotics of the calculated spectral density. It is shown that the use of the obtained spectral density correctly reproduces separately calculated moments of corresponding photon polarization operator.

The Spin Physics Detector Collaboration proposes to install a universal detector in the second interaction point of the NICA collider under construction (JINR, Dubna) to study the spin structure of the proton and deuteron and other spin-related phenomena using a unique possibility to operate with polarized proton and deuteron beams at a collision energy up to 27 GeV and a luminosity up to 10³² cm⁻² s⁻¹. As the main goal, the experiment aims to provide access to the gluon TMD PDFs in the proton and deuteron, as well as the gluon transversity distribution and tensor PDFs in the deuteron, via the measurement of specific single- and double-spin asymmetries using different complementary probes, such as charmonia, open charm, and prompt photon production processes. Other polarized and unpolarized physics is possible, especially at the first stage of NICA operation with reduced luminosity and collision energy of the proton and ion beams. This paper is dedicated exclusively to technical issues of the SPD setup construction.

Lipid–protein interactions are central to maintaining the structural and functional balance of biological membranes, influencing a wide array of cellular processes. These interactions, however, become pathological in neurodegenerative diseases (NDDs), such as Alzheimer’s, Parkinson’s, and Huntington’s diseases. In these disorders, the misfolding and aggregation of proteins like amyloid-beta (Aβ), alphasynuclein (α-syn), and mutant huntingtin (mHTT) disrupt the lipid bilayer, compromising membrane integrity, fluidity, and signaling. In this review we explore the critical role of lipid–protein interactions in NDDs, emphasizing how protein misfolding leads to toxic aggregates that embed into membranes, triggering neurotoxic events. Advanced spectroscopic techniques have been instrumental in studying these molecular interactions. Photon-based methods, including Förster resonance energy transfer (FRET), circular dichroism (CD), and Raman spectroscopy, provide real-time insights into protein aggregation and lipid membrane dynamics. Neutron-based techniques, such as neutron reflectometry and small-angle neutron scattering (SANS), further enhance the resolution of lipid–protein interactions, particularly in the context of neurodegenerative aggregation.
Moreover, the review highlights the significance of lipid microdomains, particularly cholesterol-rich lipid rafts, which act as platforms for protein aggregation, influencing disease progression. Therapeutic strategies aimed at targeting these lipid–protein interfaces are also discussed, with a focus on how spectroscopic insights have driven the development of drugs that stabilize membrane integrity or prevent toxic aggregation. Finally, the integration of spectroscopy with computational models, such as molecular dynamics (MD) simulations, is proposed as a promising approach to further unravel the complex dynamics of lipid–protein interactions, providing a more complete picture of disease mechanisms.

The article presents an overview of the work carried out at the Joint Institute for Nuclear Research in Dubna since the early 1970s aimed at creating superconducting (SC) magnets for charged particle accelerators. The specified studies made it possible to build the world’s first SC heavy-ion fast-cycling synchrotron — the Nuclotron; magnets for the SIS100 synchrotron of the FAIR project; magnetic systems of the SC Booster and collider of the NICA complex. It also resulted in a development of SC winding for magnet of the medical cyclotron for proton therapy MSC-230, a model magnet for the Chinese HIAF collider project with a record (up to 10 T/s) rate of magnetic field change, a 3-MJ energy storage device based on high-temperature superconductor (HTS), and a concept of magnets for the New Nuclotron made of HTS material for operation at a winding temperature of about 50 K.

Using the generalized renormalisation group formalism, we calculate quantum corrections to the effective potential in α-attractor models describing the inflationary stage of the Universe evolution. We demonstrate that quantum corrections lead to a change in the initial classical potential, changing its value at the minimum, which can be interpreted as a manifestation of the cosmological constant or dark energy.

The accelerator complex NICA is at the stage of assembling and commissioning. A series of successful runs at the injection complex were carried out using various types of ions. It is planned to continue the linear optics measurements at booster synchrotron, for which several methods are considered. The first one is based on the analysis of turn-by-turn data of the beam orbit going from beam position monitors. The independent component analysis is used for the data processing and results to computation of betatron and synchrotron tunes, beta-functions, phase advances and dispersions. Other methods use orbit response matrix measured with alternate kicks by dipole correctors. Accuracy of optics restoration depends on the technical feasibility of betatron tunes and orbit measurements. Various methods should be firstly accommodated to the accelerator and tested using computational model in order to conclude their potentials and form requirements for future experiments with the beam. The paper describes implementation of independent component analysis to the computer model of the NICA Booster.