bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear electrostatics: steps towards a neoclassical electron model
Authors: Delphenich D.H.
Published: June 2022

The equations of electrostatics are presented in pre‐metric form, and it is pointed out that if the origin of the nonlinearity is the constitutive law for the medium then the differential equations themselves remain linear, while the nonlinearity is confined to an algebraic equation. These equations are solved for a general class of electric fields that include the common textbook examples, namely, fields that are adapted to a coordinate vector field. The special forms that they then take for particular electric constitutive laws of quantum origin, namely, the constitutive laws derived from the Born–Infeld and Heisenberg–Euler Lagrangians, are then discussed. Finally, the classical problem of modeling the electron is redefined in light of the established facts of quantum physics.
Planck, units, and modern metrology*
Authors: Flowers Jeff L. , Petley Brian W.
Published: June 2022

Max Planck was an early proponent of the use of units based on fundamental constants, his particular system included one involving the Planck constant which emerged from his work on black‐body radiation. In this review we discuss a number of such systems and how they have a strong interplay with modern metrology and the SI system of units.
Rigorous solution of a Hubbard model extended by nearest‐neighbour Coulomb and exchange interaction on a triangle and tetrahedron
Authors: Schumann R.
Published: June 2022

The Hubbard model extended by both nearest‐neighbour (nn) Coulomb correlation and nearest‐neighbour Heisenberg exchange is solved rigorously for a triangle and tetrahedron. All eigenvalues and eigenvectors are given as functions of the model parameters in a closed analytical form. For fixed electron numbers we found a multitude of level crossings, both in the ground state and in the excited states in dependence on the various model parameters. By coupling an ensemble of clusters to an electron bath we get the cluster gas model or the cluster gas approximation, if an extended array of weak‐interacting clusters is considered. The grand‐canonical potential Ω (μ, T, h) and the electron occupation N (μ, T, h) of the related cluster gases were calculated for arbitrary values (attractive and repulsive) of the three interaction constants. For the cluster gases without the additional interactions we found various steps in N (μ, T = 0, h = 0) higher than one. The reason is the degeneration of ground states differing in their electron occupation by more than one electron. For the triangular cluster gas we have one such degeneration point. For the tetrahedral cluster gas two. As a consequence, we do not find areas with one electron in the μ‐U ground‐state phase diagram of the triangular cluster gas or with one, two and five electrons in the case of the tetrahedral cluster gas. The degeneration point of the triangular cluster gas can not be destroyed by an applied magnetic field. This holds also for the lower degeneration point of the tetrahedral cluster gas. Otherwise, the upper degeneration point breaks down at a critical magnetic field hc. The dependence of hc on U shows a maximum for strong on‐site correlation. The influence of nn‐exchange and nn‐Coulomb correlation on the ground‐state phase diagrams is calculated. Whereas antiferromagnetic nn‐exchange breaks the degeneration points of the tetrahedral cluster gas partially only, a repulsive nn‐Coulomb correlation lifts the underlying degeneracies completely. Otherwise both ferromagnetic nn‐exchange and attractive nn‐Coulomb interaction stabilise the degeneration points. The consequences of the cluster gas results for extended cluster arrays are discussed.
A novel approach to Ising problems
Authors: Hoede C. , Zandvliet H.J.W.
Published: June 2022

In 2000 Istrail suggested that calculating the partition function of non‐planar Ising models is an NP‐complete problem, implying that these problems are intractable and thus essentially unsolvable. In this note we discuss the validity of this suggestion and introduce the idea of gauging on an exact equation. We illustrate how this method works by applying it to two non‐planar Ising models, namely the 2D model with nearest and weak next nearest neighbor interactions and the anisotropic 3D model.
“… you can't say to anyone to their face: your paper is rubbish.” Max Planck as Editor of theAnnalen der Physik*
Authors: Hoffmann D.
Published: June 2022

Max Planck's place in the history of theAnnalen der Physik, which spans some two hundred years, can be characterized as unique. Planck not only published the majority of his own scientific papers in this periodical but was also connected to it personally in various editorial positions. Thus for over half a century, from 1894 until 1947, he contributed decisively toward its promotion as a leading international professional journal of modern physics. This paper documents Planck's diverse relationships with theAnnalen der Physikand analyzes his editorship against the backdrop of the evolving physics in the first quarter of the 20th century.
Ettore Majorana and his heritage seventy years later
Authors: Esposito S.
Published: June 2022

The physicists working in several areas of research know quite well the name of Ettore Majorana, since it is currently associated to fundamental concepts likeMajorana neutrinosin particle physics and cosmology orMajorana fermionsin condensed matter physics. But, probably, very few is known about other substantial contributions of that ingenious scholar, and even less about his personal background. For non specialists, instead, the name of Ettore Majorana is usually intimately related to the fact that he disappeared rather mysteriously on March 26, 1938, just seventy years ago, and was never seen again. The life and the work of this Italian scientist is the object of the present review, which will also offer a summary of the main results achieved in recent times by the historical and scientific researches on his work.
On the construction of Fermi‐Walker transported frames
Authors: Maluf J.W. , Faria F.F.
Published: June 2022

We consider tetrad fields as reference frames adapted to observers that move along arbitrary timelike trajectories in spacetime. By means of a local Lorentz transformation we can transform these frames into Fermi‐Walker transported frames, which define a standard of non‐rotation for accelerated observers. Here we present a simple prescription for the construction of Fermi‐Walker transported frames out of an arbitrary set of tetrad fields.
Pressure driven transport of glassy solid helium in cylindrical nanopores at very low temperature regime
Authors: Kwang‐Hua Chu Z.
Published: June 2022

By using the glassy helium model and boundary perturbation method, we can obtain the velocity fields (as well as the flow rate up to the second order) at very low temperature regime inside the wavy‐rough cylindrical nanopores. Our results show that the velocities of solid helium reported before by many groups could be reproduced by carefully selecting relevant physical parameters.
Coherence theory and coherence phenomena in a closed spin‐1/2 system
Authors: Dannenberg O.
Published: June 2022

A simplified Heisenberg spin model is studied in order to examine the idea of decoherence in closed quantum systems. For this purpose, we present a quantifiable definition to quantum coherence Ξ, and discuss in some detail a general coherence theory and its elementary results. As expected, decoherence is understood as a statistical process that is caused by the dynamics of the system, similar to the growth of entropy. It appears that coherence is an important measure that helps to understand quantum properties of a system, e.g., the decoherence time can be derived from the coherence function Ξ(t), but not from the entropy dynamics. Moreover, the concept of decoherence time is applicable in closed and finite systems. However, in most cases, the decay of off‐diagonal elements differs from the usual exp(‐t/τd) behaviour. For concreteness, we report the form of decoherence time τdin a finite Heisenberg model with respect to the number of particles N, density nρ, spatial dimension D and ϵ in a η/rϵ‐type of potential.
Entanglement in a periodic quench
Authors: Eisler V. , Peschel I.
Published: June 2022

We consider a chain of free electrons with periodically switched dimerization and study the entanglement entropy of a segment with the remainder of the system. We show that it evolves in a stepwise manner towards a value proportional to the length of the segment and displays in general slow oscillations. For particular quench periods and full dimerization an explicit solution is given. Relations to equilibrium lattice models are pointed out.
Strings in strongly correlated electron systems
Authors: Fulde P. , Pollmann F.
Published: June 2022

It is shown that strongly correlated electrons on frustrated lattices like pyrochlore, checkerboard or kagomè lattice can lead to the appearance of closed and open strings. They are resulting from nonlocal subsidiary conditions which propagating strongly correlated electrons require. The dynamics of the strings is discussed and a number of their properties are pointed out. Some of them are reminiscent of particle physics.
Electronic structure calculations for inhomogeneous systems: Interfaces, surfaces, and nanocontacts
Authors: Schwingenschlögl U. , Schuster C.
Published: June 2022

The article gives an introduction into the application of density functional theory (DFT) to inhomogeneous systems. To begin with, we describe the interplay of specific materials at interfaces, resulting in structure relaxation and modifications of the chemical bonding. We address interfaces between YBa2Cu3O7 and a normal metal, in order to quantify the intrinsic interface charge transfer into the superconductor. Moreover, we study the internal interfaces in a V6O13 battery cathode and the effects of ion incorporation during the charging and discharging process. The second part of the article deals with the influence of surfaces on the nearby electronic states. Here, we investigate a LaAlO3/SrTiO3 heterostructure in a thin film geometry. We particularly explain the experimental dependence of the electronic states at the heterointerface on the surface layer thickness. Afterwards, surface relaxations are studied for both the clean Ge(001) surface and for self‐assembled Pt nanowires on Ge(001). In the third part, we turn to atomic and molecular contacts. We compare the properties of prototypical Al nanocontact geometries, aiming at insight into the chemical bonding and the occupation of the atomic orbitals. Finally, the local electronic structure of a benzene‐1,4‐dithiol molecule between two Au electrodes is discussed as an example for a molecular bridge.
Proof of a decomposition theorem for symmetric tensors on spaces with constant curvature
Authors: Straumann N.
Published: June 2022

In cosmological perturbation theory a first major step consists in the decomposition of the various perturbation amplitudes into scalar, vector and tensor perturbations, which mutually decouple. In performing this decomposition one uses – beside the Hodge decomposition for one‐forms – an analogous decomposition of symmetric tensor fields of second rank on Riemannian manifolds with constant curvature. While the uniqueness of such a decomposition follows from Gauss' theorem, a rigorous existence proof is not obvious. In this note we establish this for smooth tensor fields, by making use of some important results for linear elliptic differential equations.
Special relativity in the 21st century*
Authors: Cacciatori S. , Gorini V. , Kamenshchik A.
Published: June 2022

This paper, which is meant to be a tribute to Minkowski's geometrical insight, rests on the idea that the basic observed symmetries of spacetime homogeneity and of isotropy of space, which are displayed by the spacetime manifold in the limiting situation in which the effects of gravity can be neglected, leads to a formulation of special relativity based on the appearance of two universal constants: a limiting speedcand a cosmological constant Λ which measures a residual curvature of the universe, which is not ascribable to the distribution of matter‐energy. That these constants should exist is an outcome of the underlying symmetries and is confirmed by experiments and observations, which furnish their actual values. Specifically, it turns out on these foundations that the kinematical group of special relativity is the de Sitter groupdS(c, Λ) =SO(1,4). On this basis, we develop at an elementary classical and, hopefully, sufficiently didactical level the main aspects of the theory of special relativity based onSO(1,4) (de Sitter relativity). As an application, we apply the formalism to an intrinsic formulation of point particle kinematics describing both inertial motion and particle collisions and decays.
Perfect electromagnetic conductor medium
Authors: Sihvola A. , Lindell I.V.
Published: June 2022

This article presents a review of a novel concept in electromagnetics, the Perfect Electromagnetic Conductor (PEMC). In the Minkowskian representation of the material response to electromagnetic fields, PEMC corresponds to the axion part of the constitutive tensor. From the electrical engineering point of view, PEMC is a generalization of the perfect electric conductor (PEC) and perfect magnetic conductor (PMC) materials which are useful concepts as ideal boundaries in the modeling of electromagnetic problems. PEMC is characterized by a pseudoscalar, admittance‐type parameterM, with limits 1/M→ (PEC) andM→ (PMC). This paper discusses how the PECM medium as a boundary or in particulate form generalizes earlier known electromagnetic problems (reflection, scattering, materials modeling, waveguides, resonators, image principles). The main effect of PEMC boundary is to rotate the polarization plane of the reflected electric field vector. Also practical realization aspects of a PEMC medium are discussed in the paper.
The Weinberg‐Witten theorem on massless particles: an essay
Authors: Loebbert F.
Published: June 2022

In this essay we deal with the Weinberg‐Witten theorem [1] which imposes limitations on massless particles. First we motivate a classification of massless particles given by the Poincaré group as the symmetry group of Minkowski spacetime. We then use the fundamental structure of the background in the form of Poincaré covariance to derive restrictions on charged massless particles known as the Weinberg‐Witten theorem. We address possible misunderstandings in the proof of this theorem motivated by several papers on this topic. In the last section the consequences of the theorem are discussed. We treat it in the context of known particles and as a constraint for emergent theories.
Vacuum driven accelerated expansion*
Authors: Broda B. , Bronowski P. , Ostrowski M. , Szanecki M.
Published: June 2022

It has been shown that an improved estimation of the quantum vacuum energy can yield not only theoretically acceptable but also experimentally realistic results. Our idea consists in a straightforward extraction of the gravitationally interacting part of the full quantum vacuum energy by means of gauge transformations. The implementation of this idea has been performed, in the background of a Friedmann‐Lemaître‐Robertson‐Walker geometry, by means of the euclidean version of the effective action formalism, in the language of Schwinger's proper time and Seeley‐DeWitt's heat kernel expansion.
Comment to “No‐go result for supersymmetric gauge theories in the causal approach”, by D. R. Grigore and G. Scharf (previous article: Ann. Phys. (Berlin) 17, 864 (2008))
Authors: Sibold K.
Published: June 2022

Fulfilling a request of the editor I try to put the aforementioned paper into perspective of relevant results obtained before. In particular I point out that supersymmetry of the S‐operator in cases where it exists is not necessarily in danger. Local couplings reveal however that some composite operators undergo a breaking of their supercovariance, a fact which has been established by Elisabeth Kraus.
Symanzik's method applied to fractional quantum Hall edge states
Authors: Blasi A. , Ferraro D. , Maggiore N. , Magnoli N. , Sassetti M.
Published: June 2022

The method of separability, introduced by Symanzik, is applied in order to describe the effect of a boundary for a fractional quantum Hall liquid in the Laughlin series. An Abelian Chern‐Simons theory with plane boundary is considered and the Green functions both in the bulk and on the edge are constructed, following a rigorous, perturbative, quantum field theory treatment. We show that the conserved boundary currents find an explicit interpretation in terms of the continuity equation with the electron density satisfying the Tomonaga‐Luttinger commutation relation.
Approximate record length constraints for experimental identification of dynamical fractals
Authors: Fleming S.W.
Published: June 2022

The ambiguity that can exist, for short datasets, between the observational power spectra of dynamical fractals and low‐order linear memory processes is demonstrated and explained. It is argued that it could be broadly useful to have a highly practical rule‐of‐thumb for assessing whether a data record is sufficiently long to permit distinguishing the two types of processes, and if it is not, to produce an approximate estimate of the amount of additional data that would be required to do so. Such an expression is developed using the AR(1) process as a loose benchmark. Various aspects of the technique are successfully tested using synthetic time series generated by a range of prescribed models, and its application and relevance to observational datasets is then demonstrated using examples from mathematical ecology (wild steelhead population size), geophysics (river flow volume), and econophysics (stock price volatility).
Conformal transformations and conformal invariance in gravitation
Authors: Da̧browski M.P. , Garecki J. , Blaschke D.B.
Published: June 2022

Conformal transformations are frequently used tools in order to study relations between various theories of gravity and Einstein's general relativity theory. In this paper we discuss the rules of these transformations for geometric quantities as well as for the matter energy‐momentum tensor. We show the subtlety of the matter energy‐momentum conservation law which refers to the fact that the conformal transformation “creates” an extra matter term composed of the conformal factor which enters the conservation law. In an extreme case of the flat original spacetime the matter is “created” due to work done by the conformal transformation to bend the spacetime which was originally flat. We discuss how to construct the conformally invariant gravity theories and also find the conformal transformation rules for the curvature invariants R2, RabRab, RabcdRabcd and the Gauss‐Bonnet invariant in a spacetime of an arbitrary dimension. Finally, we present the conformal transformation rules in the fashion of the duality transformations of the superstring theory. In such a case the transitions between conformal frames reduce to a simple change of the sign of a redefined conformal factor.
Information in asset pricing: a wave function approach
Authors: Ishio H. , Haven E.
Published: June 2022

This paper introduces a quantum‐like wave function as an information wave function. We show how the option pricing partial differential equation can be re‐written when we account for such information wave function. We use two stochastic differential equations, one of which relates to Nelson's hypothesis of Universal Brownian motion. We also provide for two examples which further highlight the proposed theory.
Integrability and the variational formulation of non‐conservative mechanical systems
Authors: Delphenich D.H.
Published: June 2022

It is shown that one can obtain canonically‐defined dynamical equations for non‐conservative mechanical systems by starting with a first variation functional, instead of an action functional, and finding their zeroes. The kernel of the first variation functional, as an integral functional, is a 1‐form on the manifold of kinematical states, which then represents the dynamical state of the system. If the 1‐form is exact then the first variation functional is associated with the first variation of an action functional in the usual manner. The dynamical equations then follow from the vanishing of the dual of the Spencer operator that acts on the dynamical state. This operator, in turn, relates to the integrability of the kinematical states. The method is applied to the modeling of damped oscillators.
The odd couple: Boltzmann, Planck and the application of statistics to physics (1900–1913)
Authors: Badino M.
Published: June 2022

In the last forty years a vast scholarship has been dedicated to the reconstruction of Planck's theory of black‐body radiation and to the historical meaning of quantization. Since the introduction of quanta took place for combinatorial reasons, Planck's understanding of statistics must have played an important role. In the first part of this paper, I sum up the main theses concerning the status of the quantum and compare the arguments supporting them. In the second part, I investigate Planck's usage of statistical methods and the relation to Boltzmann's analogous procedure. I will argue that this way of attacking the problem is able to give us some interesting insights both on the theses stated by the historians and on the general meaning of Planck's theory.
On the multipole moments of a rigidly rotating fluid body
Authors: Filter R. , Kleinwächter A.
Published: June 2022

Based on numerical simulations and analytical calculations we formulate a new conjecture concerning the multipole moments of a rigidly rotating fluid body in equilibrium. The conjecture implies that the exterior region of such a fluid is not described by the Kerr metric.
Stripe segregation and magnetic coupling in the nickelate La5/3Sr1/3NiO4
Authors: Schwingenschlögl U. , Schuster C. , Frésard R.
Published: June 2022

We investigate the consequences of the stripe formation in the nickelate La5/3Sr1/3NiO4 for the details of its crystal structure and electronic states. Our data are based on numerical simulations within density functional theory (DFT) and the generalized gradient approximation (GGA). The on‐site Coulomb interaction is included in terms of the LDA+U scheme. Structure optimization of preliminary experimental data indicates a strong interaction between the structural and electronic degrees of freedom. In particular, we find a segregation of the diagonal filled stripes induced by a delicate interplay with the magnetic coupling. Beyond the cooperative effect of stripe segregation and spin order, distinct octahedral distortions are essential for the formation of an insulating state.
Deformation kinetics within cylindrical micropores of glassy solid 4He at very low temperatures
Authors: K.‐H. Chu Z. , Liu S.‐J. , Qin C.
Published: June 2022

The deformation kinetics for glassy solid helium confined in microscopic domain at very low temperature regime was investigated using a transition‐rate‐state dependent model considering the shear thinning behavior which means, once material being subjected to high shear rates, the viscosity diminishes with increasing shear rate. The preliminary results show that there might be nearly frictionless fields for rate of deformation due to the almost vanishing shear stress in micropores at very low temperature regime subjected to some surface conditions: The relatively larger roughness (compared to the macroscopic domain) inside micropores and the slip. As the pore size decreases, the surface‐to‐volume ratio increases and therefore, surface roughness will greatly affect the deformation kinetics in micropores. By using the boundary perturbation method, we obtained a class of temperature and activation energy dependent fields for the deformation kinetics at low temperature regime with the presumed small wavy roughness distributed along the walls of an cylindrical micropore. The critical deformation kinetics of the glassy matter is dependent upon the temperature, activation energy, activation volume, orientation dependent and is proportional to the (referenced) shear rate, the slip length, the amplitude and the orientation of the wavy‐roughness. Finally, we also discuss the quantitative similarity between our results with Ray and Hallock [Phys. Rev. Lett. 100, 235301 (2008)].
On the pre‐metric foundations of wave mechanics I: massless waves
Authors: Delphenich D.H.
Published: June 2022

The mechanics of wave motion in a medium are founded in conservation laws for the physical quantities that the waves carry, combined with the constitutive laws of the medium, and define Lorentzian structures only in degenerate cases of the dispersion laws that follow from the field equations. It is suggested that the transition from wave motion to point motion is best factored into an intermediate step of extended matter motion, which then makes the dimension‐codimension duality of waves and trajectories a natural consequence of the bicharacteristic (geodesic) foliation associated with the dispersion law. This process is illustrated in the conventional case of quadratic dispersion laws, as well as quartic ones, which include the Heisenberg–Euler dispersion law. It is suggested that the contributions to geodesic motion from the non‐quadratic nature of a dispersion law might represent another source of quantum fluctuations about classical extremals, in addition to the diffraction effects that are left out by the geometrical optics approximation.
Nonequilibrium quantum anharmonic oscillator and scalar field: high temperature approximations
Authors: Alvarez‐Estrada R.F.
Published: June 2022

We treat a relativistic quantum boson gas, described by a scalar quantum field, with quartic self‐interaction (ϕ4) in three spatial dimensions: we review the known equilibrium case and present new proposals off‐equilibrium. For high temperature and large spatial scales, the behaviour of the gas at equilibrium simplifies nonperturbatively (equilibrium dimensional reduction or EDR): its thermodynamics is described by classical statistical mechanics with some quantum field effects. By assumption, the initial state of the gas off‐equilibrium includes interactions and inhomogeneities and is not far from thermal equilibrium. We employ real‐time generating functionals and obtain the free nonequilibrium correlators at non‐zero temperature. The nonequilibrium quantum gas appears to simplify nonperturbatively in the regime of high temperature and large temporal and spatial scales (nonequilibrium dimensional reduction or NEDR), its dynamics being described by classical statistical mechanics with some quantum field effects. We outline the renormalization of the ϕ4 theory, the nonequilibrium statistical mechanics of a quantum anharmonic oscillator and the high temperature simplifications, all of which provide very useful hints for NEDR in the field case. Our main proposals are NEDR and the associated new (renormalized) real‐time nonequilibrium generating functionals for the ϕ4 theory.
Five‐dimensional relativity and extended elementary particles
Authors: Lessner G.
Published: June 2022

Five‐dimensional relativity, based on the 5‐dimensional vacuum equations Rμν = 0, is interpreted as a general relativistic field theory describing the inner structure of extended elementary particles. The most general} spherically symmetric, purely electric and asymptotically flat solution of the field equations is calculated. The mass formula of this solution depends on two parameters h > 0 and q > 0, and the mass surface over the (h‐q)‐plane shows two slits at h= and

These slits can be tentatively identified as hadron branch for h= and lepton branch for

In the slits hadrons and leptons with their masses and extensions can be settled in local minima.
(0,2) Gauged linear sigma model on supermanifold
Authors: Okame Y. , Hayashi M.J.
Published: June 2022

We construct (0,2), D = 2 gauged linear sigma model on supermanifold with both an Abelian and non‐Abelian gauge symmetry. For the purpose of checking the exact supersymmetric (SUSY) invariance of the Lagrangian density, it is convenient to introduce a new operator for the Abelian gauge group. The operator provides consistency conditions for satisfying the SUSY invariance. On the other hand, it is not essential to introduce a similar operator in order to check the exact SUSY invariance of the Lagrangian density of non‐Abelian model, contrary to the Abelian one. However, we still need a new operator in order to define the (0,2) chirality conditions for the (0,2) chiral superfields. The operator can be defined from the conditions assuring the (0,2) supersymmetric invariance of the Lagrangian density in superfield formalism for the (0,2) U(N) gauged linear sigma model. We found consistency conditions for the Abelian gauge group which assure (0,2) supersymmetric invariance of Lagrangian density and agree with (0,2) chirality conditions for the superpotential. The supermanifold ℳ︁m|n becomes the super weighted complex projective space WCPm‐1|n in the U(1) case, which is considered as an example of a Calabi‐Yau supermanifold. The superpotential W(ϕ,ξ) for the non‐Abelian gauge group satisfies more complex condition for the SU(N) part, except the U(1) part of U(N), but does not satisfy a quasi‐homogeneous condition. This fact implies the need for taking care of constructing the Calabi‐Yau supermanifold in the SU(N) part. Because more stringent restrictions are imposed on the form of the superpotential than in the U(1) case, the superpotential seems to define a certain kind of new supermanifolds which we cannot identify exactly with one of the mathematically well defined objects.
The influence of self‐citation corrections and the fractionalised counting of multi‐authored manuscripts on the Hirsch index
Authors: Schreiber M.
Published: June 2022

The Hirsch index or h‐index is widely used to quantify the impact of an individual's scientific research output, determining the highest number h of a scientist's papers that received at least h citations. Fractionalised counting of the publications is an appropriate way to distribute the impact of a paper among all the coauthors of a multi‐authored manuscript in an easy way, leading to a simple modification hm of the h‐index. On the other hand the exclusion of self‐citations allows one to sharpen the index, what is appropriate, because self‐citations are usually not reflecting the significance of a publication. I have previously analysed the citation records of 26 physicists discussing the sharpened index hs as well as the modification hm of the original h‐index. In the present investigation I combine these two procedures yielding the modified sharpened index hms. For a better comparison, interpolated indices are utilized. The correlations between the indices are rather strong, but nevertheless the positions of some datasets change, in a few cases significantly, depending on whether they are put into order according to the values of h, hm, hs, or hms. This leads to the conclusion that the additional effort in determining the modified sharpened index hms is worth performing in order to obtain a fairer evaluation of the citation records.
Low‐frequency line temperatures of the CMB (Cosmic Microwave Background)
Authors: Hofmann R.
Published: June 2022

Based on SU(2) Yang‐Mills thermodynamics we interprete Aracde2's and the results of earlier radio‐surveys on low‐frequency cosmic microwave background (CMB) line temperatures as a phase‐boundary effect. We explain the excess at low frequencies by evanescent, nonthermal photon fields of the CMB whose intensity is nulled by that of Planck distributed calibrator photons. The CMB baseline temperature thus is identified with the critical temperature of the deconfining‐preconfining transition.
Nonlocal transformations for accelerated observers
Authors: Mashhoon B.
Published: June 2022

According to the locality postulate of special relativity, the measurements of physical fields by accelerated observers at a given event in Minkowski spacetime are related to each other by the representations of the Lorentz group. Nonlocal extensions of these representations are necessary, however, once acceleration‐induced nonlocality is taken into account. The particular case of Dirac spinors is treated in detail and the corresponding nonlocal transformation group is studied.
Indefinite oscillators and black‐hole evaporation
Authors: Kiefer C. , Marto J. , Moniz P.V.
Published: June 2022

We discuss the dynamics of two harmonic oscillators of which one has a negative kinetic term. This model mimics the Hamiltonian in quantum geometrodynamics, which possesses an indefinite kinetic term. We solve for the time evolution in both the uncoupled and coupled case. We use this setting as a toy model for studying some possible aspects of the final stage of black‐hole evaporation. We assume that one oscillator mimics the black hole, while the other mimics Hawking radiation. In the uncoupled case, the negative term leads to a squeezing of the quantum state, while in the coupled case, which includes back reaction, we get a strong entangled state between the mimicked black hole and the radiation. We discuss the meaning of this state. We end by analyzing the limits of this model and its relation to more fundamental approaches.
Manifestly covariant classical correlation dynamics I. General theory
Authors: Tian C.
Published: June 2022

In this series of papers we substantially extend investigations of Israel and Kandrup on nonequilibrium statistical mechanics in the framework of special relativity. This is the first one devoted to the general mathematical structure. Based on the action‐at‐a‐distance formalism we obtain a single‐time Liouville equation. This equation describes the manifestly covariant evolution of the distribution function of full classical many‐body systems. For such global evolution the Bogoliubov functional assumption is justified. In particular, using the Balescu‐Wallenborn projection operator approach we find that the distribution function of full many‐body systems is completely determined by the reduced one‐body distribution function. A manifestly covariant closed nonlinear equation satisfied by the reduced one‐body distribution function is rigorously derived. We also discuss extensively the generalization to general relativity especially an application to self‐gravitating systems.
Ageing in granular aluminium insulating thin films
Authors: Delahaye J. , Grenet T.
Published: June 2022

We present a new set of electrical field effect measurements on granular aluminium insulating thin films. We have explored how the conductance relaxations induced by gate voltage changes depend on the age of the system, namely the time elapsed since its quench at low temperature. A clear age dependence of the relaxations is seen, qualitatively similar to ageing effects seen in other well studied glassy systems such as spin glasses or polymers. We explain how our results differ from the previous ones obtained with different protocols in indium oxide and granular aluminium thin films. Our experimental findings bring new information on the dynamics of the system and put new constraints on the theoretical models that may explain slow conductance relaxations in disordered insulators.
1/f noise and slow relaxations in glasses
Authors: Amir A. , Oreg Y. , Imry Y.
Published: June 2022

Recently we have shown that slow relaxations in the electron glass system can be understood in terms of the spectrum of a matrix describing the relaxation of the system close to a metastable state. The model focused on the electron glass system, but its generality was demonstrated on various other examples. Here, we study the noise spectrum in the same framework. We obtain a remarkable relation between the spectrum of relaxation rates λ described by the distribution function P (λ) ∼ 1/λ and the 1/f noise in the fluctuating occupancies of the localized electronic sites. This noise can be observed using local capacitance measurements. We confirm our analytic results using numerics, and also show how the Onsager symmetry is fulfilled in the system.
Numerical study of the equilibrium thermodynamics of the Coulomb glass
Authors: Goethe M. , Palassini M.
Published: June 2022

We discuss the results of large‐scale Monte Carlo simulations of the lattice Coulomb glass model. Using the Exchange Monte Carlo algorithm we are able to equilibrate the system to very low temperature and obtain evidence against the existence of an equilibrium glass transition in three dimensions (3D). We also discuss results for the 3D Random Field Ising model that highlight the role of the interaction range. Finally, we report results for the 2D Coulomb glass, which show a behaviour very similar to the 3D case.
Study of two‐electron jumps in relaxation of Coulomb glasses
Authors: Bergli J. , Somoza A.M. , Ortuño M.
Published: June 2022

A long‐standing debate in the theory of hopping insulators concerns the role of multi‐electron transitions in the dynamics of the system. The natural assumption is that as temperature is lowered, two‐electron transitions will play an increasingly important role since they provide a way of tunneling through additional energy barriers which would be energetically unfavorable as successive one‐electron transitions. This was disputed in [1], but later it was seen in [2]. The reason for this discrepancy is not clear and deserves further attention. One point where the two approaches diverged was in the selection and weighting of the two‐electron transitions relative to one‐electron transitions. We present calculations of the transition rates to second order in the tunneling matrix element, which will be used in improved numerical studies. We compare results for only one‐electron jumps with results including also two‐electron jumps.
Effect of Fabry‐Perot resonances in disordered one‐dimensional array of alternating dielectric bi‐layers
Authors: Luna‐Acosta G.A. , Makarov N.M.
Published: June 2022

We study numerically and analytically the role of Fabry‐Perot resonances in the transmission through a one‐dimensional finite array formed by two alternating dielectric slabs. The disorder consists in varying randomly the width of one type of layers while keeping constant the width of the other type. Our numerical simulations show that localization is strongly inhibited in a wide neighborhood of the Fabry‐Perot resonances. Comparison of our numerical results with an analytical expression for the average transmission, derived for weak disorder and finite number of cells, reveals that such expression works well even for medium disorder up to a certain frequency. Our results are valid for photonic and phononic one‐dimensional disordered crystals, as well as for semiconductor superlattices.
Scaling law and critical exponent for α0 at the 3D Anderson transition
Authors: Vasquez L.J. , Slevin K. , Rodriguez A. , Roemer R.A.
Published: June 2022

We use high‐precision, large system‐size wave function data to analyse the scaling properties of the multifractal spectra around the disorder‐induced three‐dimensional Anderson transition in order to extract the critical exponents of the transition. Using a previously suggested scaling law, we find that the critical exponent ν is significantly larger than suggested by previous results. We speculate that this discrepancy is due to the use of an oversimplified scaling relation.
Spin‐dependent‐magnetoresistance control by regulation of heat treatment temperature for magnetite nano‐particle sinter
Authors: Kobori H. , Asahi T. , Yamasaki Y. , Sugimura A. , Taniguchi T. , Ando A. , Kawanaka H. , Naitoh Y. , Shimizu T.
Published: June 2022

The control of spin‐dependent‐magnetoresistance by regulation of the heat treatment (HT) temperature for magnetite (Fe3O3) nano‐particle sinter (MNPS) has been studied. The average nano‐particle size in the MNPS is 30nm and the HT was carried out from 400°C to 800°C. The HT of the MNPS varies the coupling form between adjacent magnetite nano‐particles and the crystallinity of that. The measurements on electrical resistance (ER), magnetoresistance (MR) and magnetization were performed between 4K and 300K. The behavior of the ER and MR considerably changes at the HT temperature of ∼600°C. Below ∼600°C the ER indicates the variable‐range‐hopping conduction behavior and the MR shows the large intensity in a wide temperature region. Above ∼600°C the ER shows the indication of the Verwey transition near 110K like a bulk single crystal and the MR designates the smaller intensity. We consider that below ∼600°C the ER and MR are dominated by the grain‐boundary conduction and above ∼600°C those are determined by the inter‐grain conduction. The magnetic field application to the grain‐boundary region is inferred to cause the large enhancement of the MR.
Magnetoresistance in dilute p‐Si/SiGe in parallel and tilted magnetic fields
Authors: Drichko I.L. , Smirnov I.Yu. , Suslov A.V. , Mironov O.A. , Leadley D.R.
Published: June 2022

We report the results of an experimental study of the magnetoresistance ρxx and ρxy in two samples of p‐Si/SiGe with low carrier concentrations p = 8.2 × 1010 cm‐2 and p = 2 × 1011 cm‐2. The research was performed in the temperature range of 0.3–2 K and in the magnetic fields of up to 18 T, parallel or tilted with respect to the two‐dimensional (2D) channel plane. The large in‐plane magnetoresistance can be explained by the influence of the in‐plane magnetic field on the orbital motion of the charge carriers in the quasi‐2D system. The measurements of ρxx and ρxy in the tilted magnetic field showed that the anomaly in ρxx, observed at filling factor ν = 3/2 is practically nonexistent in the conductivity σxx. The anomaly in σxx at ν = 2 might be explained by overlapping of the levels with different spins 0 ↑ and 1 ↓ when the tilt angle of the applied magnetic field is changed. The dependence of g‐factor g*(Θ)/g*(00) on the tilt angle Θ was determined.
A simple proof of the Kochen‐Specker theorem on the problem of hidden variables
Authors: Straumann N.
Published: June 2022

In this contribution I present a simple derivation of an old result of Kochen and Specker, which is apparently unrelated to the famous work of Bell on hidden variables, but is presumably equally important. Kochen and Specker showed in 1967 that quantum mechanics cannot be embedded into a classical stochastic theory, provided the quantum theoretical probability distributions are reproduced and one additional highly desirable property is satisfied. This showed in a striking manner what were the difficulties in implementing the Einstein programme of a ‘complete’ version of quantum mechanics.
Grassmann, geometric algebra and cosmology
Authors: Lasenby A.N.
Published: June 2022

Starting with Grassmann's work, a short review is given of the development of ‘Geometric Algebra’, and the reasons why it is a useful system for describing much of physics. Applications are then discussed in cosmology, including a novel boundary condition for the universe, and efficient ways to encode Bianchi cosmology. Predictions for the Cosmic Microwave Background in such models, and in another area owing much to Grassmann (String Theory), are also discussed.
Deriving spacetime from first principles
Authors: Ambjørn J. , Jurkiewicz J. , Loll R.
Published: June 2022

Causal Dynamical Triangulation is a back‐to‐basics approach to nonperturbative, background‐independent quantum gravity, which relies on few ingredients and initial assumptions, has few free parameters and – crucially – is amenable to numerical simulations. After putting the approach in context, we briefly describe its set‐up and highlight some of its major, and sometimes unexpected findings. Prominent among them is the dynamical generation of a classical de Sitter universe from Planckian quantum fluctuations.
Varying alpha
Authors: Barrow J.D.
Published: June 2022

We review properties of cosmological theories for the variation of the fine structure ‘constant’. We highlight some general features of the cosmological models that exist in these theories with reference to recent quasar data that are consistent with time‐variation in the fine structure ‘constant’ since a redshift of 3.5.
What is the dark energy paradigm?
Authors: Polarski D.
Published: June 2022

The present accelerated expansion of the universe is a major challenge for cosmology. Dark Energy models aim to explain this unconventional expansion. We have at the present time a large variety of models which are conceptually very different. We review here some of them, especially those based on a modification of the laws of gravity. Future high precision observations probing both the background and the perturbations will significantly reduce the class of viable models.
Non‐standard loop quantum cosmology
Authors: Piechocki W.
Published: June 2022

We present results concerning the nature of the cosmological big bounce (BB) transition within the loop geometry underlying loop quantum cosmology (LQC). Our canonical quantization method is an alternative to the standard LQC. An evolution parameter we use has clear interpretation both at classical and quantum levels. The physical volume operator has discrete spectrum which is bounded from below. The minimum gap in the spectrum defines a quantum of the volume. The spectra of operators are parametrized by a free parameter to be determined.
Dark energy from temporal and spatial singularities of pressure
Authors: Da̧browski M.P.
Published: June 2022

I describe an opportunity to mimic dark energy leading to a current acceleration of the universe by the application of the pressure singularities surrounding an observer. Two essentially different models are investigated. In the first one, the acceleration is due to an approach to a pressure singularity which appears on a constant time hypersurface. In the second one, the acceleration is due to the existence of the pressure singularities in some regions of space. Both models are tested positively against observations.
Dark energy from quantum fluctuations
Authors: Broda B. , Szanecki M.
Published: June 2022

We have derived the quantum vacuum pressure pvac as a primary entity, removing a trivial and a gauge terms from the cosmological constant‐like part (the zeroth term) of the effective action for a matter field. The quantum vacuum energy density

appears a secondary entity, but both are of expected order. Moreover pvac and

are dynamical, and therefore they can be used in the Einstein equations. In particular, they could dynamically support the holographic dark energy model as well as the “thermodynamic” one.
Constraining unified dark matter models with weak lensing
Authors: Camera S.
Published: June 2022

Unified Dark Matter (UDM) models provide an intriguing alternative to Dark Matter (DM) and Dark Energy (DE) through only one exotic component, i.e. a classical scalar field φ(t, x). Thanks to a non–canonical kinetic term, this scalar field can mimic both the behaviour of the matter–dominated era at earlier times, as DM do, and the outcoming late–time acceleration, as a cosmological constant DE. Thus, it has been shown that these models can reproduce the same expansion history of the ΛCDM concordance model. In this work I review the first prediction of a physical observable, the power spectrum of the weak lensing cosmic convergence (shear). I present the weak lensing signal as predicted by the standard ΛCDM model and by a family of viable UDM models parameterized by the late–time sound speed c∞ of the scalar field.last–scattering surface and a series of background galaxies peaked at different redshifts and spread over different redshifts as described by a functional form of their distribution of sources.