Physics of Particles and Nuclei
Journal Prestige (SJR): 0.342 Citation Impact (citeScore): 1 Number of Followers: 2 Hybrid journal (It can contain Open Access articles) ISSN (Print) 15318559  ISSN (Online) 10637796 Published by SpringerVerlag [2467 journals] 
 Something New about Radial Wave Functions of Fermions in the Repulsive
Coulomb Field
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Abstract: An impermeable barrier at \(r = {{r}_{{{\text{cl}}}}}\) in the effective potential of the relativistic Schrödingertype equation leads to exclusion of the range \(0 \leqslant r < {{r}_{{{\text{cl}}}}}\) from the wave function domain. Based on the duality of the Schrödingertype equation and the Dirac equation, a similar exclusion should be made in the wave function domain of the Dirac equation. As a result, we obtain new solutions to the Dirac equation in the Coulomb repulsion field. Calculations show that depending on working parameters, at distances of fractions or units of the Compton wavelength of the fermion from \(r = {{r}_{{{\text{cl}}}}}\) new solutions almost coincide with the standard Coulomb functions of the continuous spectrum. Practically, matrix elements with new solutions will coincide to a good accuracy with standard matrix elements with the Coulomb functions of the continuous spectrum. Our consideration is methodological and helpful for discussing further development of quantum theory.
PubDate: 20221201

 Superoperator Approach to the Theory of Hot Nuclei and Astrophysical
Applications. III: Neutrino–Nucleus Reactions in Stars
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Abstract: The influence of thermal effects on neutrino–nucleus reactions occurring under supernova conditions is studied. The approach used is based on the quasiparticle random phase approximation extended to finite temperatures using the superoperator formalism. Using the example of the 56Fe and 82Ge nuclei, a detailed analysis of the influence of thermal effects on the strength function of Gamow–Teller transitions, which dominate in the lowenergy chargeneutral and chargeexchange reactions, is performed. Neutrino cross sections for inelastic scattering and capture by hot nuclei are calculated and compared with the results of the shell model calculations. The influence of thermal effects on the spectrum of scattered neutrinos and on the process of energy exchange between neutrino radiation and nuclei is considered. The energyloss rates in the process of neutrino–antineutrino pair emission by deexcitation of hot nuclei are calculated.
PubDate: 20221201

 Magnetism in FerromagneticSuperconducting Layered Structures

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Abstract: The review presents the results of studies by neutrons of the magnetism phenomena in ferromagneticsuperconducting inhomogeneous structures carried out by the authors over fifteen years. The presence of superparamagnetic clusters, ferromagnetic domains, and superconducting vortices in real inhomogeneous layered structures leads to new magnetic phenomena. Reflectometry of polarized neutrons, being a powerful method for studying the spatial distribution of magnetization on a spatial scale from fractions of nanometers to tens of microns, makes it possible to study the whole spectrum of magnetic phenomena that occur in ferromagneticsuperconducting structures.
PubDate: 20221201

 A Noninvasive MuonographyBased Method for Exploration of Cultural
Heritage Objects
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Abstract: An innovative noninvasive method of muonography based on emulsion detectors has been developed. The new method enables detection of changes in the fluxes of atmospheric muons passing through the object under study and determination of the specific features of its internal structure. Owing to the use of the stateoftheart automated scanning facilities, largescale studies of natural and industrial objects can be carried out that require processing of large quantity of photoemulsion. A major muonography experiment, in which the internal structure of buildings and the territory of the SvyatoTroitsky Danilov Monastery had been examined, is described in detail.
PubDate: 20221201

 Results on Bose–Einstein Correlations of Charged Hadrons in pp
Collisions at 13 TeV in CMS
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Abstract: Femtoscopic correlations between charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons, in protonproton collisions at \(\sqrt s = \) 13 TeV. The results are based on data collected with the CMS detector at the LHC in 2015, during runs with a special low pileup configuration. Three analysis techniques with different dependencies on simulations are used to remove the nonBose–Einstein background from the correlation functions, and are found to give consistent results. Onedimensional studies of the lengthsofhomogeneity, \({{R}_{{{\text{inv}}}}}\) , and the intercept parameter, \(\lambda \) , have been carried out for both inclusive events and high multiplicity events selected using a dedicated online trigger. The measured lengths of homogeneity are studied as functions of particle multiplicity, pair average transverse momentum and pair average transverse mass. The results are compared with those from CMS collected at lower centerofmass energies and to data from other LHC experiments, as well as with theoretical expectations from the color glass condensate and from hydrodynamic models.
PubDate: 20221201

 Microscopically Derived Grodzins Relation and Prediction of the Excitation
Energies of the $$2_{1}^{ + }$$ States for Some Superheavy Nuclei
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Abstract: The microscopic variant of the Grodzins relation derived based on the Geometrical Collective Model and a microscopic approach to description of the lowenergy nuclear structure is applied to predict the excitation energies of the \(2_{1}^{ + }\) states of nuclei with Z \( \geqslant \) 100. It is shown that at the beginning of the chain of the studied nuclei the excitation energies of the \(2_{1}^{ + }\) states do not exceed 80 keV. Then \(E(2_{1}^{ + })\) sharply increases with A and reaches maximum value of 400–500 keV in \(^{{290}}\) Lv or \(^{{294}}\) Og depending on the microscopic variant of the Grodzins relation used in the calculations.
PubDate: 20221201

 Superoperator Approach to the Theory of Hot Nuclei and Astrophysical
Applications: I—Spectral Properties of Hot Nuclei
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Abstract: The method of superoperators in Liouville space was applied to study spectral properties of hot nuclei. It is shown that properly defined fermionic superoperators allow us to generalize the equationofmotion method to hot nuclei. Within the superoperator approach, for the nuclear model with separable particle–hole residual interaction of Landau–Migdal type, we derived the equations of thermal quasiparticle random phase approximation, which allow the spectral densities and strength functions of chargeexchange and chargeneutral excitations of hot nuclei to be calculated in a thermodynamically consistent way, i.e., without violating the principle of detailed balance. For the quasiparticlephonon nuclear model, a thermodynamically consistent way is proposed for going beyond the random phase approximation by considering the interaction of thermal phonons. Using the Donnelly–Walecka method and the superoperator approach, expressions for cross sections of semileptonic weak reactions with hot nuclei are obtained.
PubDate: 20221001
DOI: 10.1134/S1063779622050033

 Superoperator Approach to the Theory of Hot Nuclei and Astrophysical
Applications: II—Electron Capture in Stars
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Abstract: Electron captures on nuclei play an essential role in the dynamics of the collapsing core of a massive star that leads to a supernova explosion. We propose a novel thermodynamically consistent approach to calculate capture rates and cross sections of \({{e}^{  }}\) capture on hot nuclei in the stellar interior. The method is based on the quasiparticle random phase approximation extended to finite temperature using the tool of the superoperator formalism. By the example of \(^{{54,56}}\) Fe it is shown that thermodynamically consistent incorporation of thermal effects leads to a stronger temperature dependence of the \({{e}^{  }}\) capture rates and cross sections for iron group nuclei than predicted by the shellmodel calculations. The combined action of thermal effects and pairing correlations on the unblocking of Gamow–Teller \(p \to n\) transitions is considered for neutronrich nuclei around N = 50. It is shown that it is thermal effects that lead to the unblocking of lowenergy transitions. Due to this, as well as to the contribution of forbidden transitions, the electron capture does not stop at nuclei with N = 50.
PubDate: 20221001
DOI: 10.1134/S1063779622050045

 Topical Problems of Beam Dynamics in the NICA Collider

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Abstract: — The NICA project is under development at the Joint Institute for Nuclear Research (Dubna, Russia). The accelerator complex is at the stage of stepwise assembly and commissioning. The facility is created for solution of fundamental problems in the field of the quark–gluon plasma and a number of applied experiments; it consists of two superconducting synchrotrons and a superconducting collider. Two linear accelerators play the role of injectors; particles from protons to heavy highly ionized ions are produced by ion sources. The main stage of the project will be commissioning of the Collider. Multiple studies of the beam dynamics at the design stage were the basis of design development of the Collider systems: the accelerator lattice, and the beam correction and control. The choice of its operation parameters is based on numerical calculation of movement of charged particles in the Collider rings, which were multiply performed by different groups of researchers using various methods, algorithms, and simulation codes. Some tasks still remain topical. Some of them are fundamental, and directly affect the understanding of the beam motion in the facility and require thorough study using threedimensional particle tracking taking account of all the main physical phenomena in beams and nonlinearities in the system. In the NICA, such problems are collective effects, which are mainly the subject of this work. The motion of ions is considered, taking into account the action of space charge of the beam, intrabeam scattering, effects of interacting beams, and the electron cooling system. The problem of the interaction of the circulating beam with beam elements of the Collider and the effect of electron clouds are discussed. The first results of numerical calculations with threedimensional particle tracking codes are presented. The paper describes the current state of numerical and theoretical calculations of the beam stability in NICA and the plans for solution of the uncompleted tasks.
PubDate: 20221001
DOI: 10.1134/S1063779622050057

 Cascade Models in Simulation of Extended Heavy Targets Irradiated by
Accelerated Proton and Deuteron Beams
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Abstract: The paper presents a survey of the main numerical models used for simulation of interaction of accelerated particle beams with target nuclei. These models form the core of the software for simulation of various experiments and experimental facilities both for scientific and applied purposes. The beam and target parameters considered in detail in this study (protons and deuterons with energies from 0.66 to 4 AGeV and bulk U targets) cover the range of interest in development of new concepts of nuclear power production aided by accelerated particle beams.
PubDate: 20221001
DOI: 10.1134/S1063779622050021

 Studying the Variation of Fundamental Constants at the Cosmic Ray
Extremely Distributed Observatory
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Abstract: The study of the variation of fundamental constants through time or in localized regions of space is one of the goals of the Cosmic Ray Extremely Distributed Observatory which consists of multiple detectors over the Earth. In this paper, the various effects which can be potentially identified through cosmic rays detections by CREDO are presented.
PubDate: 20220801
DOI: 10.1134/S1063779622040025

 Precision Spectroscopy of the Hydrogen Molecular Ions: Present Status of
Theory and Experiment
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Abstract: We review recent experiments on HD+ spectroscopy. The reduced protondeuteron mass to electron mass ratio, \({{\mu }_{{pd}}}{\text{/}}{{m}_{e}}\) , is inferred from the comparison of theory and experiment. Theoretical issues related to the calculations of the spin structure, which are currently the main limiting factor of theoretical accuracy, are discussed.
PubDate: 20220801
DOI: 10.1134/S1063779622040086

 Advantages of a Novel Approach to the Numerical Evaluation of the Muon g
– 2 Anomaly
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Abstract: Few advantages of the novel approach of a numerical evaluation of the muon g – 2 anomaly in comparison with the classical approach are discussed, which lead to a deviation from the world averaged experimental value by \(1.6{\kern 1pt} \sigma \) .
PubDate: 20220801
DOI: 10.1134/S1063779622040062

 Hyperfine Spectroscopy of Antihydrogen, Hydrogen, and Deuterium

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Abstract: The prospects of tests of CPT symmetry using precision spectroscopy of antihydrogen are discussed with special emphasis on the groundstate hyperfine structure, a measurement of which is the aim of the ASACUSA collaboration at the AD/ELENA facility of CERN. Ongoing parallel experiments using hyperfine spectroscopy of hydrogen and deuterium aiming at studying Lorentz invariance by determining coefficients of the Standard Model Extension framework are described.
PubDate: 20220801
DOI: 10.1134/S1063779622040141

 Critical Exponents of Model with Matrix Order Parameter from Resummation
of SixLoop Results for Anomalous Dimensions
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Abstract: In this contribution an application of two techniques for resummation of asymptotic series namely Borel–Pade technique and Borel–Leroy technique with conformal mapping to the case of a model with multiple coupling constants will be discussed and the results of application of these methods to the \(O(n)\) symmetric \({{\phi }^{4}}\) model with a real antisymmetric tensor order parameter will be presented.
PubDate: 20220801
DOI: 10.1134/S1063779622040104

 The Complete α8m Contributions to the 1s Lamb Shift in Hydrogen

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Abstract: Precision studies of simple atoms, such as hydrogen, play an essential role in tests of boundstate QED and determining fundamental constants, such as the Rydberg constant and the proton charge radius. One of the QED predictions is for the Lamb shift of hydrogenic energy levels and, in particular, of the ground state. The value of the \(1s\) Lamb shift in hydrogen and deuterium is required for an accurate determination of the Rydberg constant and the proton charge radius utilizing data from highresolution spectroscopy of hydrogen and deuterium atoms, as well as for precision tests of boundstate QED. The dominant QED contribution to the uncertainty is due to the \({{\alpha }^{8}}m\) externalfield contributions. We discuss here our recent results on the two and threeloop contributions, which essentially reduce the theoretical uncertainty. Combined with recent calculations of Laporta on the slope of the Dirac form factor in the threeloop level, our results allow for completion of calculations of \({{\alpha }^{8}}m\) contributions to the Lamb shift of the ground state in the hydrogen atom.
PubDate: 20220801
DOI: 10.1134/S1063779622040074

 Search for Light Bosons with King and SecondKing Plots Optimized for
Lithium Ions
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Abstract: The King plot technique widely used for isotopes of heavy atoms is extended to light heliumlike ions by taking second differences to eliminate large mass polarization corrections. The effect of a hypothetical electronneutron interaction propagated by light bosons is included and a comprehensive survey of all secondKing plot transitions for all states of Li+ up to \(n = 10\) and \(L = 7\) is presented in order to find the ones most sensitive to new physics due to light bosons. The sensitivity is found to be comparable to that for the recently studied case of Yb+.
PubDate: 20220801
DOI: 10.1134/S1063779622040037

 A New Mechanism for Sympathetic Cooling of Atoms and Ions in Atomic and
IonAtomic Traps
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Abstract: Sympathetic cooling of a Fermi gas with a buffer gas of bosonic atoms is an efficient way to achieve quantum degeneracy in Fermi systems. However, all attempts to use this method for cooling ions until recently were ineffective because of the unremovable ion “micromotion” in electromagnetic Paul traps, which prevents the realization of a number of hot projects with cold atomion systems. In this regard, we propose a new efficient method for sympathetic cooling of ions: the use for this purpose of cold buffer atoms in the region of atomion confinementinduced resonances (CIRs) [V.S. Melezhik, Phys. Rev. A103, 53109 (2021)]. We show that the destructive effect of “micromotion” on its sympathetic cooling can, however, be suppressed in the vicinity of the atomion CIR. Here, the resonant blocking of a close collision of an atom with an ion also resists its heating due to “micromotion”. We investigate the effect of sympathetic cooling around CIRs in atomion, and atomatom confined collisions within the quantumquasiclassical approach using the Li–Yb+ and Li–Yb confined systems as an example. In this approach, the Schrödinger equation for a cold light atom is integrated simultaneously with the classical Hamilton equations for a hotter heavyion or atom during a collision. We have found the region near the atomion CIR where the sympathetic cooling of the ion by cold atoms is possible in a hybrid atomion trap. We also show that it is possible to improve the efficiency of sympathetic cooling in atomic traps by using atomic CIRs.
PubDate: 20220801
DOI: 10.1134/S1063779622040116

 A Method of Fast Calculaion of Lepton Magnetic Moments in Quantum
Electrodynamics
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Abstract: A new method of divergence subtraction in Feynman parametric integrals is presented. The method is suitable for calculating the lepton anomalous magnetic moments (AMM) in quantum electrodynamics (QED). The subtraction procedure eliminates all divergences before integration and leads to a finite Feynman parametric integral for each individual Feynman diagram. It is based on a forest formula with linear operators applied to the Feynman amplitudes of ultravioletdivergent subdiagrams. The formula is similar to Bogoliubov–Parasiuk–Hepp–Zimmermann summation; the difference is only in the linear operators used and in the way of combining them. The subtraction is equivalent to the onshell renormalization from the beginning: for obtaining the final result we should only sum up the contributions of all Feynman diagrams after subtraction. The developed method is an improvement of the method presented by the author in 2016. The modification is specifically designed for calculating the contributions dependent on the relations of particle masses. In comparison with the old version, the new subtraction formula does not contain redundant terms and possesses some flexibility that can be used for improving the precision of calculations. Numerical test results are presented up to four loops.
PubDate: 20220801
DOI: 10.1134/S106377962204013X

 Complex Phase Dynamics of Overlimiting Electron Beams Propagating in
Opposite Directions
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Abstract: Results of PIC simulation of the phase dynamics of counterpropagating overlimiting electron beams injected in opposite directions into various axially symmetric cavities are reviewed. Multiple examples of the complex dynamics of the beams are presented, in which virtual cathodes, phasespace holes, and squeezed state regions containing a dense charged electron plasma are formed. Space and time characteristics of the processes and the density, temperature, and lifetime of the electron plasma are estimated. Possible experiments and potential applications of counterpropagating overlimiting electron beams in various areas of science and technology are considered, including RF electronics, ultrawideband electronics, particle accelerators, and electric discharges in gases.
PubDate: 20220801
DOI: 10.1134/S1063779622040049
