bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrodynamics of spin currents in superconductors
Authors: Hirsch J.E. 
Published: June 2022

AbstractIn recent work we formulated a new set of electrodynamic equations for superconductors as an alternative to the conventional London equations, compatible with the prediction of the theory of hole superconductivity that superconductors expel negative charge from the interior towards the surface. Charge expulsion results in a macroscopically inhomogeneous charge distribution and an electric field in the interior, and because of this a spin current is expected to exist. Furthermore, we have recently shown that a dynamical explanation of the Meissner effect in superconductors leads to the prediction that a spontaneous spin current exists near the surface of superconductors (spin Meissner effect). In this paper we extend the electrodynamic equations proposed earlier for the charge density and charge current to describe also the space and time dependence of the spin density and spin current. This allows us to determine the magnitude of the expelled negative charge and interior electric field as well as of the spin current in terms of other measurable properties of superconductors. We also provide a `geometric' interpretation of the difference between type I and type II superconductors, discuss how superconductors manage to conserve angular momentum, discuss the relationship between our model and Slater's seminal work on superconductivity, and discuss the magnitude of the expected novel effects for elemental and other superconductors.
Waiting times and noise in single particle transport
Authors: Brandes T. 
Published: June 2022

AbstractThe waiting time distribution w(τ), i.e. the probability for a delay τ between two subsequent transition (‘jumps’) of particles, is a statistical tool in (quantum) transport. Using generalized Master equations for systems coupled to external particle reservoirs, one can establish relations between w(τ) and other statistical transport quantities such as the noise spectrum and the Full Counting Statistics. It turns out that w(τ) usually contains additional information on system parameters and properties such as quantum coherence, the number of internal states, or the entropy of the current channels that participate in transport.
On the advancements of conformal transformations and their associated symmetries in geometry and theoretical physics*
Authors: Kastrup H.A. 
Published: June 2022

AbstractThe historical developments of conformal transformations and symmetries are sketched: Their origin from stereographic projections of the globe, their blossoming in two dimensions within the field of analytic complex functions, the generic role of transformations by reciprocal radii in dimensions higher than two and their linearization in terms of polyspherical coordinates by Darboux, Weyl's attempt to extend General Relativity, the slow rise of finite dimensional conformal transformations in classical field theories and the problem of their interpretation, then since about 1970 the rapid spread of their acceptance for asymptotic and structural problems in quantum field theories and beyond, up to the current AdS/CFT conjecture. The occasion for the present article: hundred years ago Bateman and Cunningham discovered the form invariance of Maxwell's equations for electromagnetism with respect to conformal space‐time transformations.
Maxwell's equations in Minkowski's world: their premetric generalization and the electromagnetic energy‐momentum tensor
Authors: Hehl F.W. 
Published: June 2022

AbstractIn December 1907, Minkowski expressed the Maxwell equations in the very beautiful and compact 4‐dimensional form: lor f = ‐s, lor F*= 0. Here ‘lor’, an abbreviation of Lorentz, represents the 4‐dimensional differential operator. We study Minkowski's derivation and show how these equations generalize to their modern premetric form in the framework of tensor and exterior calculus (valid also in general relativity). After mentioning some applications of premetric electrodynamics, we turn to Minkowski's discovery of the energy‐momentum tensor of the electromagnetic field. We discuss how he arrived at it and how its premetric formulation looks like.
Backwards on Minkowski's road. From 4D to 3D Maxwellian electromagnetism
Authors: Itin Y. , Friedman Y. 
Published: June 2022

AbstractMinkowski's concept of a four‐dimensional physical space is a central paradigm of modern physics. The three‐dimensional Maxwellian electrodynamics is uniquely generalized to the covariant four‐dimensional form. Is the (1+3) decomposition of the covariant four‐dimensional form unique? How do the different sign assumptions of electrodynamics emerge from this decomposition? Which of these assumptions are fundamental and which of them may be modified? How does the Minkowski space‐time metric emerge from this preliminary metric‐free construction? In this paper we are looking for answers to the problems mentioned. Our main result is the derivation of four different possible sets of electrodynamic equations which may occur in different types of isotropic electromagnetic media. The wave propagation in each of these media is described by the Minkowskian optical metrics. Moreover, the electric and magnetic energies are nonnegative in all cases. We also show that the correct directions of the Lorentz force (as a consequence of the Dufay and the Lenz rules) hold true for all these cases. However, the differences between these four types of media must have a physical meaning. In particular, the signs of the three electromagnetic invariants are different.
No‐go result for supersymmetric gauge theories in the causal approach
Authors: Grigore D.R. , Scharf G. 
Published: June 2022

AbstractWe consider the massless supersymmetric vector multiplet in a purely quantum framework and propose a power counting formula. Then we prove that the interaction Lagrangian for a massless supersymmetric non‐Abelian gauge theory (SUSY‐QCD) is uniquely determined by some natural assumptions, as in the case of Yang‐Mills models. The result can be easily generalized to the case when massive multiplets are present, but one finds out that the massive and the massless Bosons must be decoupled, in contradiction with the standard model. Going to the second order of perturbation theory produces an anomaly which cannot be eliminated. We make a thorough analysis of the model working only with the component fields.
Approximate l‐state solutions of the D‐dimensional Schrödinger equation for Manning‐Rosen potential
Authors: Ikhdair S.M. , Sever R. 
Published: June 2022

AbstractThe Schrödinger equation in D‐dimensions for the Manning‐Rosen potential with the centrifugal term is solved approximately to obtain bound states eigensolutions (eigenvalues and eigenfunctions). The Nikiforov‐Uvarov (NU) method is used in the calculations. We present numerical calculations of energy eigenvalues to two‐ and four‐dimensional systems for arbitrary quantum numbers n and l with three different values of the potential parameter α. It is shown that because of the interdimensional degeneracy of eigenvalues, we can also reproduce eigenvalues of a upper/lower dimensional system from the well‐known eigenvalues of a lower/upper dimensional system by means of the transformation (n,l,D) → (n,l ± 1,D ∓ 2). This solution reduces to the Hulthén potential case.
DMRG studies of critical SU(N) spin chains
Authors: Führinger M. , Rachel S. , Thomale R. , Greiter M. , Schmitteckert P. 
Published: June 2022

AbstractThe DMRG method is applied to integrable models of antiferromagnetic spin chains for fundamental and higher representations of SU(2), SU(3), and SU(4). From the low energy spectrum and the entanglement entropy, we compute the central charge and the primary field scaling dimensions. These parameters allow us to identify uniquely the Wess–Zumino–Witten models capturing the low energy sectors of the models we consider.
Superfluid to Mott‐insulator transition in an anisotropic two‐dimensional optical lattice
Authors: Polak T.P. , Kopeć T.K. 
Published: June 2022

AbstractWe study the superfluid to Mott‐insulator transition of bosons in an optical anisotropic lattice by employing the Bose‐Hubbard model living on a two‐dimensional lattice with anisotropy parameter κ. The compressible superfluid state and incompressible Mott‐insulator (MI) lobes are efficiently described analytically, using the quantum U(1) rotor approach. The ground state phase diagram showing the evolution of the MI lobes is quantified for arbitrary values of κ, corresponding to various kind of lattices: from square, through rectangular to almost one‐dimensional.
A look at the abandoned contributions to cosmology of Dirac, Sciama, and Dicke
Authors: Unzicker A. 
Published: June 2022

AbstractThe separate contributions to cosmology of the above researchers are revisited and a cosmology encompassing their basic ideas is proposed. We study Dirac's article (1938) on the large number hypothesis, Sciama's proposal (1953) of realizing Mach's principle, and Dicke's considerations (1957) on a flat‐space representation of general relativity with a variable speed of light (VSL). Dicke's tentative theory can be formulated in a way which is compatible with Sciama's hypothesis on the gravitational constant G. Additionally, such a cosmological model is shown to satisfy Dirac's second ‘large number’ hypothesis on the total number of particles in the universe being proportional to the square of the epoch. In the same context, Dirac's first hypothesis on an epoch‐dependent G – contrary to his prediction – does not necessarily produce a visible time dependence of G. While Dicke's proposal reproduces the classical tests of GR in first approximation, the cosmological redshift is described by a shortening of measuring rods rather than an expansion of space. Since the temporal evolution of the horizon R is governed by , the flatness and horizon problems do not arise in the common form.
The momentum of electromagnetic waves in dielectric materials*
Authors: Dick R. 
Published: June 2022

AbstractVariation of the generally covariant version of Minkowski's Lagrangian of macroscopic Maxwell theory with respect to the metric yields a symmetric tensor Tμν which reproduces the Poynting vector 𝒮i = cT0i, and therefore would seem to favor Abraham's proposal 𝒫Ai = 𝒮i/c2 for the momentum density in a macroscopic electromagnetic wave. However, the T00 component does not reproduce the standard energy density in the rest frame in the flat limit. The difference between the energy density and T00 has the same structure as the difference between the Minkowski momentum density 𝒫Mi = n2𝒮i/c2 and the Abraham momentum density. The result therefore adds further credibility to Minkowski's original energy‐momentum tensor and his proposal for the total momentum density of electromagnetic waves in dielectric materials. We draw attention to the facts that the covariant formulation of macroscopic Maxwell theory of dielectric materials requires a field strength‐velocity coupling term which could only be inferred in a long wavelength limit from quantum electrodynamics, and that the theory is clearly limited to interactions of sub‐UV photons with matter. Therefore, in spite of the fact that macroscopic Maxwell theory can formally be written in generally covariant terms, the theory for n ≠ 1 should be considered as inherently non‐relativistic, with non‐relativistic corrections of order n ‐ 1. The difference 𝒫M ‐ c‐2 𝒮 between Minkowski's momentum density and the rescaled Poynting vector is an example of an order n ‐ 1 correction.
Improved analytical approximation to arbitrary l‐state solutions of the Schrödinger equation for the hyperbolical potential
Authors: Ikhdair S.M. , Sever R. 
Published: June 2022

AbstractA new approximation scheme to the centrifugal term is proposed to obtain the l ≠ 0 bound‐state solutions of the Schrödinger equation for an exponential‐type potential in the framework of the hypergeometric method. The corresponding normalized wave functions are also found in terms of the Jacobi polynomials. To show the accuracy of the new proposed approximation scheme, we calculate the energy eigenvalues numerically for arbitrary quantum numbers n and l with two different values of the potential parameter σ0. Our numerical results are of high accuracy like the other numerical results obtained by using program based on a numerical integration procedure for short‐range and long‐range potentials. The energy bound‐state solutions for the s‐wave (l = 0) and σ0 = 1 cases are given.
A new look at Bell's inequalities and Nelson's theorem
Authors: Schulz B. 
Published: June 2022

AbstractIn 1985, Edward Nelson, who formulated the theory of stochastic mechanics, made an interesting remark about Bell's theorem. Nelson analysed the latter in the light of classical fields that behave randomly. He found that if a stochastic hidden variable theory fulfils certain conditions, the inequality of Bell can be violated. Moreover, Nelson was able to prove that this may happen without any instantaneous communication between the two spatially separated measurement stations. Since Nelson's article got almost overlooked by physicists, we try to review his comments on the theorem. We argue that a modification of stochastic mechanics published recently by Fritsche and Haugk can be extended to a theory which fulfils the requirements of Nelson's analysis. The article proceeds to derive the quantum mechanical formalism of spinning particles and the Pauli equation from this version of stochastic mechanics. Then, we investigate Bohm's version of the EPR experiment. Additionally, other setups, like entanglement swapping or time and position correlations, are shortly explained from the viewpoint of our local hidden‐variable model. Finally, we mention that this theory could perhaps be relativistically extended and useful for the formulation of quantum mechanics in curved space‐times.
Quantum field theory and composite fermions in the fractional quantum Hall effect
Authors: Kossow M. 
Published: June 2022

AbstractWe derive a composite fermion model for the fractional quantum Hall effect from relativistic quantum electrodynamics. With simple arguments it is shown that a special Chern Simons transformation of the Dirac electrons in four spacetime dimensions leads in the low energy limit to a single particle Hamiltonian for composite fermions in three dimensions with correction terms such as Rashba‐ or Dresselhaus‐spin‐orbit coupling and zitterbewegung. Furthermore we provide a mechanism to quantum‐mechanically project the quantum fields defined in the four dimensional Minkowski space to three dimensions. This leads to a relativistic field theory and especially a composite fermion field theory in three dimension. This projection map can be combined with the projection onto a Landau level or composite fermion Landau level respectively. This results in a quasi relativistic quantum field theory on a noncommutative plane. The phenomenological models resulting from this approach are discussed and allow a systematical exploration of the effects of the spin and the condensation in a Landau level. We expect from the relativistic approach corrections in terms of spin‐orbit coupling effects. From the projection onto Landau levels we expect a modification of the dispersion relation and a modified composite fermion mass. Furthermore, the BRST quantization for Chern Simons theories with compact gauge group is reviewed and the phenomenological consequences within a composite fermion model with spin are discussed. The connection to Wess Zumino Witten theories is recalled and a possible link between the corresponding central charge of the related affine Lie algebra and the composite fermion filling factor is pointed out.
The mathematical pendulum from Gauß via Jacobi to Riemann
Authors: Dittrich W. 
Published: June 2022

AbstractThe goal of this article is to introduce double‐periodic elliptic functions on the basis of a “simple” mechanical system, that of the mathematical pendulum. Thereby it is not geometry that is in the foreground, as in Gauß's analysis of the lemniscatian curve, but rather the calculation of the specific attributes of elliptic functions with the aid of a periodic integrable system. Not the spatial degree of freedom, but the time variable is continued into the complex plane. This will make it possible for us to not only identify the known real period of the pendulum oscillation, but also to detect a second imaginary period. Only then does the solution of the equation of motion become a Jacobi‐type elliptic function. Using the Cauchy integral theorem, which Gauß was already familiar with, as well as the simplest Riemannian surface of the function

we want to calculate the analytic and topological characteristics of the oscillatory motion of a pendulum. Our intent is to show that elliptic functions could have appeared much earlier than 1796 in the literature. Admittedly, for this the field of complex numbers was necessary, as represented in the Gaußian plane of complex numbers. However, Gauß was unwilling to publish his findings because of his “fear of the cry of the Boeotians”.
Gravitoelectromagnetic cavitons in the kinetic regime
Authors: Li X.Q. , Liu S.Q. , Tao X.Y. 
Published: June 2022

AbstractWe consider the interaction of gravitational fields (including “gravitoelectromagnetism”) with interstellar matter dealing with resonant wave‐particle and wave‐wave interactions on the basis of magnetic‐type Maxwell‐Vlasov equations. It is found that the behavior of the perturbed GEM fields, the perturbed density and self‐generated gravitomagnetic field with very low frequency, can be described by the nonlinear coupling Eqs. (98–100). Numerical results show that they may collapse. In other words, due to self‐focusing, a stronger GEM fields magnified up to 103 times, could be produced; they are the GEM cavitons, describing gravity shielding and filament effects. And the self‐generated gravitomagnetic field is concurrently focused by the background material to a small space where it may be detected.
Intrinsic decoherence in the interaction of two fields with a two‐level atom
Authors: Juárez‐Amaro R. , Escudero‐Jiménez J.L. , Moya‐Cessa H. 
Published: June 2022

AbstractWe study the interaction of a two‐level atom and two fields, one of them classical. We obtain an effective Hamiltonian for this system by using a method recently introduced that produces a small rotation to the Hamiltonian that allows to neglect some terms in the rotated Hamiltonian. Then we solve a variation of the Schrödinger equation that models decoherence as the system evolves through intrinsic mechanisms beyond conventional quantum mechanics rather than dissipative interaction with an environment.
Ultra‐fast dynamics in solids: non‐equilibrium behaviour of magnetism and atomic structure
Authors: Bennemann K.H. 
Published: June 2022

AbstractNon‐equilibrium physics is of fundamental interest, for example, for extensions of statistical mechanics and thermodynamics. In particular, it is important to understand how conservation laws like energy conservation and angular‐momentum conservation in magnetic solids control the time scale of the dynamics. Laser irradiation may cause intense electronic excitations and thus a strong non‐equilibrium state. Results are presented for the ultra‐fast response of magnetism in ferromagnetic transition metals like Ni, Co, Fe, and Gd and furthermore of the atomic structure in semiconductors like Si, Ge, and InSb. Non‐thermal melting is a most spectacular example of ultra‐fast bond breaking. Time‐resolved magnetooptical experiments yielding sub‐picosecond spin dynamics are discussed. The spin dynamics is accompanied by THz light emission. The structural changes in semiconductors, bond changes sp3 → s2p2, and phase transitions occur within about 100 fs. The results also shed light on electron‐transfer processes, on ionization, and on molecular dissociation dynamics, which may occur during fs and as times. We discuss the application of time‐resolved analysis to tunnelling problems and the phase diagram of high‐Tc superconductivity.
Entanglement of spin chains with general boundaries and of dissipative systems
Authors: Stauber T. , Guinea F. 
Published: June 2022

AbstractWe analyze the entanglement properties of spins (qubits) close to the boundary of spin chains in the vicinity of a quantum critical point and show that the concurrence at the boundary is significantly different from the one of bulk spins. We also discuss the von Neumann entropy of dissipative environments in the vicinity of a (boundary) critical point, such as two Ising‐coupled Kondo‐impurities or the dissipative two‐level system. Our results indicate that the entanglement (concurrence and/or von Neumann entropy) changes abruptly at the point where coherent quantum oscillations cease to exist. The phase transition modifies significantly less the entanglement if no symmetry breaking field is applied and we argue that this might be a general property of the entanglement of dissipative systems. We finally analyze the entanglement of an harmonic chain between the two ends as function of the system size.
Thermal dynamics at surfaces
Authors: Brune H. 
Published: June 2022

AbstractThe present paper describes what happens at the surface of a crystal as its temperature steadily increases from zero Kelvin close to the bulk melting temperature. We treat thermal motion, such as the diffusion of individual adatoms establishing mass transport, the formation of adatom or vacancy gases coexisting with islands or steps of the condensed phase, surface phonons and the anharmonicity of the surface potential being markedly different from the one in bulk, as well as thermally induced reconstructions, surface roughening, and finally surface melting, which usually well precedes bulk melting. The paper intends to give an overview with references to the original and review literature.
The “writing on the cosmic wall”: Is there a straightforward explanation of the cosmic microwave background?
Authors: Fahr H.J. , Zönnchen J.H. 
Published: June 2022

AbstractTheCosmicMicrowaveBackground (CMB) is taken today as reflecting the thermodynamical state of the universe at these early cosmic times. Based on this assumption and standard cosmological principles meanwhile many fundamental cosmological facts have been deduced from the CMB state which, however, to some surprise reveal that the universe should be dominated by dark energy and dark matter, while for its energy content the usual baryonic matter is nearly negligible. Thus the question which we want to raise in this article is, whether this standard interpretation of the CMB phenomenon is solid and unequivocal enough to support the standard cosmological claims. We shall show, however, that in many details the standard explanation is not straightforward, but allows for important alternatives which seriously should be looked at. Especially arguments for a vanishing cosmic curvature (k = 0) are shown to be weak, and, contrary to the usual claim, the light distance to the recombination horizon is in fact strongly model‐biassed. We also show that the CMB dipole which is generally understood as a consequence of a peculiar motion by about 680 km/s with respect to rest system of the CMB can as well, and perhaps even better, be understood as indication of differerent cosmological expansion dynamics seen in an anisotropically expanding universe in different directions of the sky. We also discuss that the power amplitude (i.e. effective Planck temperature) in the dipolar CMB structure depends on wavelength even inverting the dipole maximum orientation in the Wien's branch. In addition unexpected properties of the lowest CMB multipoles could mean that we are at least partly seeing an unquantifyable foreground in the background. Only after its removal the CMB interpretation could at all then, but then on a completely new basis, become a subject of cosmological terms. At the end of this article we shall briefly discuss an alternative explanation of the CMB radiation which helps to better understand the mysterious cosmic photon‐to‐baryon ratio of about 109.