This review discusses the physical nature and conditions governing the phenomenon of slow nuclear burning in a breeding medium - “nuclear deflagration”- specifically in the breeding zone of a fast breeder reactor. A brief overview is provided of various theoretical approaches to describing this phenomenon and the results obtained based on them [1–4]. The results of our study of the nuclear...
Quasi-Linkage Equilibrium (QLE) is a theory developed by Kimura (1965) and Neher & Shraiman (2009:2011) to explain the emergency of distributions of genotypes in a population akin to the canonical ensemble in statistical physics, referred to as a QLE state. Recombination (exchange of genetic material between individuals) acts analogously to molecular collisions in kinetic gas theory, and...
Studies of low-temperature ordering in long-range interacting many-particle systems continue to attract significant interest. While such systems are common in nature, some features of their critical behavior remain unexplained. We address the combined impact of weak structural disorder and weak long-range interactions decaying in $d$-dimensional space as $x^{-d-\sigma}$ with $\sigma > 0$ on...
Analytical [1] and numerical [2] study of the magnetic field impact on the dynamics of electrosolitons, i.e., charged Davydovs solitons, in one-dimensional systems has shown that in the presence of the field soliton velocity and acceleration attains oscillations with the frequency determined by the field. It has been shown that the impact of a magnetic field within both approaches depends not...
We analyse the possibility of the application of the statistical-mechanical approaches developed in the modern theory of associative fluids for the description of associative phenomena on different properties in soft matter theory [1]. In developed theoretical formalism, the potentials of intermolecular interactions are split into three parts. One of them is the short-range repulsive part...
"Designs" are sets of points, for example on a sphere, that have the property that averages of polynomials over the set coincide with averages over the whole sphere. Similarly for the unitary group.
One can treat these points as interacting particles, and use liquid theory to study the problem. I will present the problem as seen from a physicist's point of view.
The relationship between the macroscopic dynamics of matter, viewed as a continuous medium, and that of its microscopic corpuscular constituents is a paramount challenge in physics. Its prominent 20th-century formulation is Hilbert’s sixth problem, which specifically calls for 'developing mathematically the limiting processes... which lead from the atomistic view to the laws of motion of...
Entanglement in parameterized quantum circuits and its quantification on quantum computers
Kh. P. Gnatenko
Ivan Franko National University of Lviv, Professor Ivan Vakarchuk Department for Theoretical Physics, 12 Drahomanov St., Lviv, 79005
SoftServe Inc., 2d Sadova St., 79021 Lviv, Ukraine
We study entanglement in multi-qubit variational quantum circuits with different...
We investigate the hydrodynamic and quantum evolution of dark matter (DM) modeled as a Bose–Einstein condensate (BEC) with axion-like self-interaction within dwarf galaxies. The periodic nature of the interaction induces a multiphase halo structure with alternating stability zones, where low-density spatial tails undergo spinodal decomposition and fragment into clump- and foam-like structures...
The exchange of matter and energy between an open system and its surroundings triggers thermally activated spontaneous processes that drive entropy toward a maximum. Consequently, thermal equilibration is fundamentally entropy-driven, establishing a final equilibrium state whose population increases with temperature. In certain cases, this behavior manifests as an entropy-driven thermal...
An important problem in the statistical description of big data random sequences is identifying macroscopic characteristics that summarize the essential properties of the system while ignoring microscopic details. These characteristics are analogous to thermodynamic variables that describe the macroscopic state of a physical system composed of many interacting degrees of freedom. Markov chains...
A system consisting of a large number of relativistic charged particles is considered. An expression for the friction coefficient in momentum space has been derived based on particle dynamics under the action of the total force of binary interaction between charged particles. The derived formulas determine the particle friction coefficients in momentum space, both during the kinetic stage of...
Transport of a passive scalar in a given field is a common problem in plasma systems, the atmosphere, ocean flows, etc. It can be formulated as a problem to recover the temporal evolution of a particle ensemble in a given field based on known statistical characteristics of this field. An important peculiarity in such a system concerns the interplay of two time scales, namely the correlation...
The report presents results of the Heisenberg Cut study in the theory of quantum measurement. The solution to the problem was obtained thanks to perception of the impossibility of direct quanta measurement. An indirect test requires a deepening of the random variable definition via the Kolmogorov triad by the Frechet representation of a random element.
Measurement in general is a...
We present a unified framework connecting Calabi--Yau geometry, singularity theory, and early-universe cosmology within heterotic and Type IIB string compactifications. Starting from the Tian--Yau threefold defined by its complete-intersection configuration matrix $P^3$ [3 0 1] ${P}^3$ [0 3 1], we demonstrate how a free $\mathbb{Z}_3$ quotient reduces the Euler characteristic to...
Ya. D. Krivenko-Emetov$^{1,2,3,*}$ and B. I. Sydorenko$^{2,\dagger}$
$^{1}$National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", Kyiv, Ukraine;$^{2}$Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv, Ukraine;$^{3}$Taras Shevchenko National University of Kyiv, Kyiv, Ukraine$^{*}$y.kryvenko-emetov@kpi.ua; $^{\dagger}$former member of...
We construct a simple equation of state of strongly interacting matter at zero chemical potentials that provides a unified description of lattice QCD thermodynamics in terms of hadronic and partonic degrees of freedom. The hadronic phase is described by the quantum van der Waals hadron resonance gas, extended by excluded-volume repulsion between mesons, while the quark-gluon plasma is modeled...
Theoretical analysis of astrophysical S-factors of nuclear reactions
$^{7}$Be(n,$\alpha )^{4}$He and $^{7}$Be(n,p)$^{7}$Li
V.I. Zhaba, V.S. Vasilevsky, Yu.A. Lashko
Bogolyubov Institute for Theoretical Physics, National Academy of Sciences
of Ukraine
In this report, we study a range of reactions induced by the interactions $^{7}$Li+p, $^{7}$Be+n and $^{6}$Li+d. Special attention is...
We study an interacting relativistic system of charged bosons at finite temperature and fixed isospin density within a thermodynamically consistent mean-field approach. Two forms of repulsive self-interaction, $φ^4$ and $φ^6$, are considered. The interactions lead to a density-dependent effective mass $M$ of the bosonic quasiparticles and an associated excess-pressure contribution. The...
It was shown earlier that size effect of soft phonon dispersion is principally important in nanosized ferroics [1]. Also, the size and strain effects can determine the anomalous polarization reversal in strained thin films of van der Waals ferrielectrics [2]. It has been shown recently that the influence of the flexoelectric coupling (shortly “flexocoupling”) on the fluctuations of electric...
One of the problems of analyzing experimental electrophysical dependences is determining the parameters of the theoretical model that best reproduces the form of measured dielectric response of ferroelectric-dielectric nanocomposites. For complex nonlinear models, such a problem may have several close solutions, be sensitive to the initial approximation, and require significant computational...
Metallized DNA is of considerable interest due to its potential application in molecular electronics. Therefore, the fundamental properties of this system are of paramount interest, in particular those related to electronic structure and dynamics of metallized base pairs. In this work, two different structural motifs of Ag-DNA known from the experiment [1,2] were investigated: one that...
The complexes of monovalent ions (Li$^+$, Na$^+$, K$^+$) with DNA phosphate groups are considered in the present work. The complexes are studied from the simplest to the more complicated ones. In addition, chloride ions (Cl$^-$) and water molecules are introduced to make the complexes more realistic. Optimized geometries, interaction energies, and vibrational spectra are calculated using...
The DNA macromolecule has nanometer dimensions, a double helix structure consisting of chemically bonded atoms, and a large negative charge. Being in an aqueous environment or inside cells, the DNA macromolecule interacts mainly through electrostatic forces, hydrogen bonds, hydration and biochemical bonding, including medium ions, so the environment strongly influences DNA conformation,...
DNA is a strong polyanionic polyelectrolyte with the properties, which are largely governed by interactions with charged ions (counterions) in aqueous solution. Alkali metal cations differ substantially in ionic radius, charge density, and hydration enthalpy, which in turn determine how strongly they bind to the phosphate backbone, reorganize the surrounding hydration shell, and affect...
The non-stationary longitudinal Josephson effect in bilayer systems with pairing of spatially separated electrons and holes is investigated [1]. The tunneling current between two weakly coupled electron-hole condensates (right and left) is analyzed in the presence of an external voltage applied along the layers. Two limiting regimes are considered: the high-density regime, where pairing occurs...
Quantum chemical study of methanol interaction with a pyrene-based acid
Kremen O. S.1, Bychko I. B.2, Nikolaienko T.Y.3, Lobanov V. V.1, Strizhak P. E.2
1Chuiko Institute of Surface Chemistry of the NAS of Ukraine,
Oleh Mudrak Str., 17, Kyiv-03164, Ukraine, kremenoksana@ukr.net
2L. V. Pisarzhevskii Institute of Physical Chemistry of the NAS of Ukraine,
Prospect Nauki, 31,...
Organic solar cells based on non-fullerene acceptors (NFAs) are a promising direction in the development of organic photovoltaics due to the possibility of targeted molecular design and control of their electronic and optical properties. Particular attention is paid to A–D–A-type acceptors, including ITIC and its fluorinated derivatives, for which the introduction of fluorine atoms provides an...
A hypercomplex method for solving the piecewise-continuous Dirichlet problem for the Lamé system in domains with corner points has been developed, which is based on the representation of solutions using the components of a monogenic function in a commutative biharmonic algebra. Using a biharmonic integral of the Cauchy type, the Dirichlet problem has been reduced to a system of integral...
The Boltzmann equation [1] that describes the evolution of rarefied gases is one of the main equations of the kinetic theory of gases. For a model of rough spheres, the equation has the form:
\begin{equation}
D(f)= Q(f,f),
\end{equation}
where the left-hand side of the equation is the differential operator:
$$ D(f)\equiv\frac{\partial f}{\partial t}+\left(V,\frac{\partial f}{\partial...
By a copolynomial we mean here a linear functional on the space of polynomials $\mathbb{R}[x]$. The space of copolynomials is denoted by $\mathbb{R}[x]'$. If $T\in\mathbb{R}[x]'$ and $p\in\mathbb{R}[x]$, then the result of application of $T$ to $p$ is written as $(T,p)$. The derivative $T'$ of a copolynomial $T\in\mathbb{R}[x]'$ is defined in the same way as in the classical theory of...
We study a mathematical model describing viscous fingering induced by the chemical reaction $A+B \to C$, introduced in [T. Gerard and A. De Wit, Phys. Rev. E, 2009]. The model couples the concentrations of the reactants, $u(t,x,y)$ and $v(t,x,y)$, and their product, $w(t,x,y)$, with the pressure $p(t,x,y)$ and the two-dimensional velocity field $U=(U_1,U_2)$, and is given by
$ \nabla\cdot...
$\quad$Using the set of independent Symmetric Tamm-Dancoff (STD) type $q$-deformed quantum oscillators [1] with the standard linear-in-$N$ Hamiltonian, we construct respective gas of $q$-bosons. Such a deformed $q$-Bose gas model admits [2] exact analytic expressions for the $r$-particle momentum correlation function, and corresponding intercepts, of any $r$th order. This is the third example...
The speed of quantum state evolution is a fundamental characteristic of quantum dynamics. As shown in [1], for pure quantum states, it is directly governed by energy fluctuations. In the present work, we examine the speed of quantum evolution in a spin system described by the Ising model and subjected to a longitudinal magnetic field. We perform analytical derivations and quantum computing...
We predict an anomalous collision-energy dependence of proton-number
fluctuations as a consequence of the onset of deconfinement in heavy-ion collisions at the nucleon-pair centre-of-mass energy (8 − 12) GeV. The effect arises from the change of properties of the effective degrees of freedom during the transition from confined and deconfined matter. The proposed interpretation provides a...
Understanding the properties of strongly interacting matter is one of the central challenges in high-energy physics. In heavy-ion collisions, nuclei are smashed together at relativistic speeds to recreate extreme conditions of temperature and density, briefly producing a state of matter known as the quark-gluon plasma. This hot, dense matter behaves as a nearly perfect liquid — flowing with...
The multiplicity dependence of the two-particle Bose-Einstein momentum correlation radii in pp collisions at the LHC has been measured at a fixed energy of collisions. One notable feature of these measurements is that the effective system’s volume, when extracted from the correlation radius parameters, appears to scale nearly linearly with charged-particle multiplicity [1-3], except for low...
The macroscopic model for neutron stars (NSs) as a cold perfect fluid in equilibrium within the Tolman-Oppenhiemer-Volkoff (TOV) theory is extended to a small rotational angular momentum I around the symmetry axis. The deformed NS surface was taken into account in the leptodermic approximation $a/R<<1$, where $a$ is an inner crust thickness and $R$ is the NS radius. Using the linear...
Effective field theories (EFTs) allow for a systematic description of processes at a particular energy scale, even for strongly interacting systems where no small coupling constants exist. EFTs link scattering and matter, topics of a great tradition of research at BITP. I will discuss two contemporary systems where structure emerges from essentially one parameter: $^4$He atoms and nucleons.
To resolve a long-standing problem of nuclear astrophysics regarding of synthesis of $^{12}$C and heavier nuclei, in 1953, F. Hoyle suggested that the nuclei $^{12}$C were created in a collision of three alpha particles. This collision leads to the creation of a very narrow (long-lived) 0$^{+}$ resonance state, which emits a photon and then transforms into a bound state of $^{12}$C. Moreover,...
The momentum correlations in pairs of non-identical particles produced in heavy-ion collisions can be used to determine the space-time asymmetries in the radiation of the two particle species [1]. And these asymmetries, in turn, reflect the peculiarities of the underlying collision dynamics.
Since the system created in a relativistic heavy-ion collision undergoes collective expansion, one...
The graphene has become a widely investigated material since its controlled isolation and identification 20 years ago, and it started the boom of the two dimensional materials. The electronic, mechanical and other properties of graphene are affected by the native defects in it. Here we study the simple one, a mono-vacancy. A question about its mobility has been raised by the community of...
The "genealogy" of theoretical physics in Kharkiv from the beginning of the 1930s to the present is presented. The connection is traced both at the level of research topics and at the level of interpersonal relations between representatives of the Kyiv school of theoretical physics, founded by M.M. Bogolyubov, and the Kharkiv school of theoretical physics, founded by L.D. Landau and O.I....
TBA
Axion-like particles (ALPs) coupled to photons can modify electromagnetic spectra through conversion in astrophysical magnetic fields. In galaxy clusters, turbulence makes this effect stochastic and strongly dependent on the magnetic-field realisation for individual sightlines. Recent work showed that averaging over ensembles of background active galactic nuclei transforms these fluctuations...
The coherent effects present in atomic K-shell ionization and the subsequent emission of characteristic X-ray radiation (CXR) induced by ultrashort relativistic electron bunches are investigated [1]. The approach distinguishing close and distant collisions was applied to calculate the K-shell ionization cross section. The cross section associated with close collisions is independent on the...
In this talk the Standard Model of the neutron decay is described by the exchange of the electroweak $W$ boson. However, energy scales for this process ($\sim \mathrm{MeV}$) are well below the electroweak scale ($\sim 100~\mathrm{GeV}$). Consequently, the historical description within the low-energy effective field theory (EFT) is the correct physics picture for the neutron decay, on the one...
Research into stochastic processes with resetting is currently in a phase of intensive development. After the initial period, when the main effects of optimizing target search in basic random walk models were identified, researchers moved on to studying more complex problems with a focus on their practical aspects. One example is the process of sequentially locating/destroying multiple targets...
Recent experimental studies have shown that magnonics—an independent branch of spintronics—can realize its potential in nanotechnology applications involving magnetophotonics, thermal nanoconversion, magnonic capacitors, magnonic transistors, and other fields. Magnons are very good candidates for use in quantum communication. This is because the transport of magnons as uncharged quasiparticles...
Physical modeling of macroscopic properties of the complex many-particle, poly-dispersive micromechanical (granular) systems
O.I. Gerasymov, A.Ya. Spivak#
State University of Intelligent Technology and Telecommunications, Odesa
*National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute, Kyiv
Odesa National Mechnikov’s University
The study of the influence on the...
High-efficiency acceleration of charged particle beams in the plasma wakefield accelerator was studied experimentally and by numerical simulation. The most impressive experimental results [1] until now in electron accelerating by a wakefield, excited in a plasma, have been achieved using capillary-generated plasma. Plasma-wakefield acceleration provides high accelerating gradients [1,2],...
Analytic higher order perturbative calculations in quantum field theory lead to special function spaces representig the Feynman integrals. We report on the recently obtained $q$- and $\mu$-extensions of these special function spaces.
The talk provides an overview of recent progress in the mathematical understanding
of kinetic equations that govern quantum systems with many particles.
The talk will begin by discussing an approach to describing the evolution of correlations in systems of many quantum particles. This method is based on the von Neumann hierarchy of evolution equations for a sequence of correlation...
We investigate the critical behavior and phase structure of nonlinear sigma models on real Stiefel manifolds SO(N)/SO(N-k), with particular focus on the SO(5)/SO(2) model and its relation to the $SO(5)$-based Zhang model of competing antiferromagnetic and superconducting orders. The Stiefel model is characterized by two effective interaction coupling constants, which give rise to a...
In various statistically defined situations, like referendum, epidemic threshold, mass service process or a chemical sensor the probability of overall output coincides with the probability that a threshold $N_0$ number of elementary events has been achieved. The latter depends on the probability $p$ that a single elementary event happens. Elementary event for a referendum case is the positive...
In this talk, a notion of irregular conformal blocks in two-dimensional conformal
field theory will be presented. It is expected that such irregular conformal blocks are related to the isomonodromic tau functions of Painlevé equations. I will consider, as an example, the Painlevé I equation and give details of the relation to irregular conformal field theory.
We elaborate a systematic way to obtain higher order contributions in the nonlinear steepest descent method for Riemann-Hilbert problem associated with homogeneous Painleve II equation. The problem is reformulated as a matrix factorization problem on two circles and can be solved perturbatively reducing it to finite systems of algebraic linear equations. The method is applied to find...
Eleven years ago we developed the four-component nonlinear integrable dynamical system on a ribbon of two-leg triangular lattice with the common coherent and uncommon background-controlled intersite couplings [1, 2]. The system can be classified as a sort of semi-discrete nonlinear Schrödinger system. It characterized by four basic (independent) fields on zero background and two concomitant...
In one-dimensional quantum mechanics, shrinking a system to isolated points (set of Lebesgue's measure zero) leads to exactly solvable models. These models are referred to as point (contact or zero-range) interactions (PIs). In these cases,resolvents and spectra of Schroedinger operators, scattering coefficients and other characteristics can analytically be computed. Currently, because of the...
Direct numerical simulation of open quantum systems is limited by the quadratic memory cost of storing the density matrix. We present a deterministic low-rank propagation method for time-local Markovian dynamics. The method applies to Hamiltonians composed of a time-dependent diagonal part and terms that become tridiagonal after suitable permutations of the basis, as well as to collapse...
This talk concerns the Cauchy problem for the following two-component Novikov system:
$\begin{align}
&m_t+(uvm)_x+u_xvm=0,
&& m=m(t,x),\,u=u(t,x),\,v=v(t,x),\\
&n_t+(uvn)_x+uv_xn=0,
&& n=n(t,x),\\
&m=u-u_{xx},\,\,n=v-v_{xx},
&& u,v\in\mathbb{R},\quad
t,x\in\mathbb{R},
\end{align}$
It is well-known that this system admits the wave-breaking phenomena: the slope of solution...
The flexoelectric-type coupling between the gradients of electric polarization, described by a true polar vector $\vec{P}$, and the antiphase rotation of structural groups, described by an axial pseudovector $\vec{\Phi }$, can lead to the appearance of interfacial polarization at the twin walls, antiphase boundaries and surfaces of antiferrodistortive (AFD) ferroelastics [1]. The...
We investigate the emergence of correlated electron phases in rhombohedral $N$-layer graphene due to two-valley Coulomb interactions within a low-energy $k \cdot p$ framework. Analytical expressions for Lindhard susceptibilities in intra- and intervalley channels are derived, and the critical temperatures for phase transitions are estimated using both the random phase approximation (RPA) and...
It is demonstrated that the description of electron states in a one-dimensional crystal with account of electron spin should be based on the Dirac theory. Electron spin states are determined by the eigen states of the spinor invariants with their free parameters.
It is shown that in the case of atomic chain with the cylindric symmetry integrals of motion include a set of spinor operators...
It is widely accepted that phonons in a superfluid Bose gas are Goldstone bosons, and that the spontaneous breaking of $U(1)$ symmetry is the primary cause of superfluidity. The first statement is justified by spontaneous symmetry breaking (SSB), which is usually defined as follows: the Hamiltonian of the system is invariant under the $U(1)$ transformation $\hat{\Psi}(\mathbf{r},t)\rightarrow...
The magnon-driven transport properties of a two-dimensional model of a $d$-wave altermagnet are investigated. As a case study, we consider a rutile with easy-planar anisotropy (e.g., $\mathrm{NiF}_2$), where the sublattice magnetization vectors lie within the $xy$-plane in the equilibrium state. An external magnetic field is applied perpendicular to this plane, along the $z$-axis. The model...
This work presents a fully quantum-mechanical theoretical framework for describing electron dynamics and collective phenomena in a cylindrical crossed-field configuration subject to a spatially periodic boundary potential. The electron cloud is considered in orthogonal radial electric and axial magnetic fields. By solving the Schrödinger equation with the corresponding gauge potentials and an...
