Physics of Particles and Nuclei最新文献

We remind the origin of the proton spin problem in deep inelastic scattering, then discuss the recent RHIC data and demonstrate that complementing the RHIC data with theoretical calculations in double-logarithmic approximation solves the proton spin problem even when contributions of the angular orbital momentum of the partons are not taken into account.

This paper explores the duality between chiral symmetry breaking and charged pion condensation within the Polyakov extended Nambu–Jona-Lasinio (PNJL) model, which incorporates confinement phenomena absent in the traditional NJL model framework that describes only chiral dynamics. The PNJL model in addition incorporates the Polyakov loop to include confinement and the confinement-deconfinement transition, enabling a more comprehensive exploration of QCD phase structure under conditions of finite temperature and baryon density. The thermodynamic potential of dense quark matter with isospin and chiral imbalances obtained in PNJL model is analyzed. It is shown analytically that the duality between chiral symmetry breaking and charged pion condensation remains intact and persists in PNJL model across both confined and deconfined phases, i.e., regardless of the value of the Polyakov loop.

Color confinement is a fundamental phenomenon in quantum chromodynamics. In this work, the mechanisms underlying color confinement are investigated in detail, with a particular focus on the role of non-perturbative phenomena such as center vortices and monopoles in the QCD vacuum. By exploring lattice QCD approaches, including the Maximal Center Gauge and center projection methods, we examine how these topological structures contribute to the confining force between color charges. We also address the limitations of conventional methods and suggest improvements to the gauge fixing prescription to enhance the accuracy of string tension predictions. Our findings support the validity of the center vortex model as a key candidate for understanding the dynamics of the confining QCD vacuum.

This is a cursory overview of the development of theoretical ideas in the studies of strong interactions from the 1920s to our days.

Abstract—This essay is written on the occasion of the 160th anniversary of the birth of Hermann Minkowski and devoted to the analysis of his creative heritage from the perspective of modern physics. Considerable attention is paid to the issue of relevance and optimal methods for teaching the four-dimensional picture of event space in high schools and universities. The researcher may be interested in those parts of the paper that discuss the unresolved conceptual and mathematical problems which arose in connection with Minkowski’s great geometric insight.

The soft and hard QCD processes are analyzed by ALICE, ATLAS and CMS experiments using samples of proton-proton and AA collisions collected by the LHC at different energies. Measurements of jet production rates, jet properties, particle multiplicity, particle momentum spectra and correlations are presented. The results are compared to predictions of theoretical models at leading- and next-to-leading orders of QCD. The data in combination with HERA and CMS and ATLAS results are used to measure the strong coupling constant and for PDF constraints.

The possible fine structure of differential cross sections of nucleon elastic scattering at small angles at high energies is considered. A brief historical overview of various approaches to the problem under consideration is given. The presence of a periodic structure in differential cross sections at LHC energies is considered by a model-independent method and within the framework of the new Regge-eikonal model taking into account the generalized structure of nucleons (HEGS model). The analysis of new effects discovered on the basis of experimental data at 13 TeV and associated with the specific properties of the hadron potential at large distances is carried out taking account of all sets of experimental data on elastic (pp) scattering obtained at (sqrt s = 3.6) up to (sqrt s = 13) TeV in a wide momentum transfer region. It also gives quantitative descriptions of all examined experimental data with a minimum number of fitting parameters. It is shown that the new features determined at a high statistical level give an important contribution to the differential cross sections and allow the research into hadron interactions at large distances.

The paper is devoted to the discussion of the possibility of creating UCN sources based on the principle of pulsed accumulation (PA) in traps. The implementation of the PA principle would make it possible to create a source with a flux of UCN in a trap significantly exceeding the time average. The paper provides a comparative analysis of various approaches to the implementation of the idea of PA of UCN in traps remoted from the place of their generation. Based on this analysis, the concept of the UCN source, the creation of which is planned at the IBR-2M pulse reactor, was formulated. A distinctive feature of the designed source is a combination of several approaches to ensuring the pulsed structure of neutron bunches reaching the UCN trap. One of them is the deceleration of the pulsed flux of VCN using a resonant flipper, the second is the use of compensating time lenses.

We consider neutron transfer reactions (^{7}{text{Li}})((d),(p))(^{8}{text{Li}}) and neutron capture (^{7}{text{Li}})((d),(t))(^{6}{text{Li}}) as sources of information on the structure of lithium nuclei in excited, including exotic, states. The analysis is based on the use of new experimental data measured at an energy of ({{E}_{{{text{LAB}}}}}(d)) = 14.5 MeV at the U-150M isochronous cyclotron of the Institute of Nuclear Physics (INP), Almaty, Republic of Kazakhstan, as well as on previously obtained data. The analysis of differential cross-sections has been conducted within the framework of the finite-range distorted waveband approximation (FRDWBA) and a phenomenological approach based on solving an approximate equation for the form factor. The obtained values of nuclear vertex constants (NVC) and asymptotic normalization coefficients (ANC) are compared with theoretical model calculations and other empirical data. The obtained radial dependences of reaction form factors for various states shows that the wave function of the (^{6}{text{Li}}) nucleus in the 3.56 MeV state has an increased spatial size compared to the ground state, both of these states having larger sizes than the 2.19 MeV state. This result indicates the existence of a halo in the 3.56 MeV state, while the presence of a halo in the ground state of (^{6}{text{Li}}) remains an open question. For (^{8}{text{Li}}), comparison of radial form factor dependences has shown that spatial sizes of the ground state and the excited state (0.98 MeV) are close. Probably both states have a skin-like structure.

The production of heavy quark and lepton bound states in the decay of the Higgs boson has been studied. Various decay mechanisms have been considered that make a significant contribution to the Higgs boson decay width. When calculating the decay widths, we take into account relativistic corrections both in the decay amplitude and in the wave function of the bound state of the particles.