bluuebunny/crossref_metadata_2025_split huggingface dataset:
3D parton imaging of the nucleon in high‐energy pp and pA collisions*
Authors: Frankfurt L. , Strikman M. , Weiss C. 
Published: June 2022

AbstractWe discuss several examples of how the transverse spatial distribution of partons in the nucleon, as well as multiparton correlations, can be probed by observing hard processes (dijets) in high‐energy and pA (dA collisions. Such studies can complement the information gained from measurements of hard exclusive processes in ep scattering. The transverse spatial distribution of partons determines the distribution over pp impact parameters of events with hard dijet production. Correlations in the transverse positions of partons can be studied in multiple dijet production. We find that the correlation cross section measured by the CDF Collaboration, σeff = 14.5±1.7+ 1.7‐2.3 mb, can be explained by “constituent quark” type quark–gluon correlations with rq ≊ rN / 3, as suggested by the instanton liquid model of the QCD vacuum. Longitudinal and transverse multiparton correlations can be separated in a model‐independent way by comparing multiple dijet production in pp and pA collisions. Finally, we estimate the cross section for exclusive diffractive Higgs production in pp collisions at LHC (rapidity gap survival probability), by combining the impact parameter distribution implied by the hard partonic process with information about soft interactions gained in pp elastic scattering.
SU(3) systematization of baryons: Theoretical methods and mixing with the antidecuplet*
Authors: Guzey V. , Polyakov M.V. 
Published: June 2022

AbstractWe take a fresh look at the SU(3) systematization of all known baryons with mass less than 2000 MeV. We describe well‐known and new theoretical tools used in grouping elementary particles into unitary multiplets and present the emerging picture of the unitary multiplets and their mixing. The issue of multiplet mixing is discussed in detail with an emphasis on the mixing with the antidecuplet. While SU(3) does not strongly require that the antidecuplet mixes with any established octet or decuplet, it is still possible to mix the antidecuplet with a JP=1/2+ octet. However, the mixing parameters cannot be reliably determined this way. Instead, one should consider decays of the antidecuplet members.
Brownian motion: a paradigm of soft matter and biological physics
Authors: Frey E. , Kroy K. 
Published: June 2022

AbstractThis is a pedagogical introduction to Brownian motion on the occasion of the 100th anniversary of Einstein's 1905 paper on the subject. After briefly reviewing Einstein's work in a contemporary context, we pursue several lines of further developments and applications to soft condensed matter and biology. Over the last century Brownian motion has been promoted from an odd curiosity of marginal scientific interest to a guiding theme pervading all of the modern life sciences.
Brownian motors
Authors: Hänggi P. , Marchesoni F. , Nori F. 
Published: June 2022

AbstractIn systems possessing a spatial or dynamical symmetry breaking, thermal Brownian motion combined with unbiased, non‐equilibrium noise gives rise to a channelling of chance that can be used to exercise control over systems at the micro‐ and even on the nano‐scale. This theme is known as the “Brownian motor” concept. The constructive role of (the generally overdamped) Brownian motion is exemplified for a noise‐induced transport of particles within various set‐ups. We first present the working principles and characteristics with a proof‐of‐principle device, a diffusive temperature Brownian motor. Next, we consider very recent applications based on the phenomenon of signal mixing. The latter is particularly simple to implement experimentally in order to optimize and selectively control a rich variety of directed transport behaviors. The subtleties and also the potential for Brownian motors operating in the quantum regime are outlined and some state‐of‐the‐art applications, together with future roadways, are presented.
From Einstein's 1905 postulates to the geometry of flat space‐time
Authors: Mermin N.D. 
Published: June 2022

AbstractMinkowski diagrams in 1+1 dimensional flat space‐time are given a strictly geometric derivation, directly from two gedanken experiments incorporating the principle of the constancy of the velocity of light and the principle of (special) relativity. Rectangles of photon trajectories play a central role in determining the simultaneity convention and in establishing the invariance of the interval.
Gravitation: geometry and dynamics
Authors: Schäfer G. 
Published: June 2022

AbstractThe paper reviews general relativity, Einstein's theory of gravitation. Emphasis is put on the invariance groups of general coordinate and local Lorentz transformations. The presentation of the dynamics is based on Schwinger's action principle and the Hamiltonian approach. The machinery of accelerated reference frames in Minkowski space is discussed. Observer‐relevant results from post‐Newtonian calculations are presented, experimental tests of the foundations and the predictions of the theory are summarized.
Cosmological constant and vacuum energy
Authors: Volovik G.E. 
Published: June 2022

AbstractThe general thermodynamic analysis of the quantum vacuum, which is based on our knowledge of the vacua in condensed‐matter systems, is consistent with the Einstein earlier view on the cosmological constant. In the equilibrium Universes the value of the cosmological constant is regulated by matter. In the empty Universe, the vacuum energy is exactly zero, λ=0. The huge contribution of the zero point motion of the quantum fields to the vacuum energy is exactly cancelled by the higher‐energy degrees of freedom of the quantum vacuum. In the equilibrium Universes homogeneously filled by matter, the vacuum is disturbed, and the energy density of the vacuum becomes proportional to that of matter, λ=ρvac∼ρmatter. This consideration applies to any vacuum in equilibrium irrespective of whether the vacuum is false or true, and is valid both in Einstein's general theory of relativity and within the special theory of relativity, i.e. in a world without gravity.
Properties of entanglement in interacting spin systems
Authors: Fazio R. , Macchiavello C. 
Published: June 2022

AbstractWe briefly review recent work on entanglement with particular emphasis on its behaviour in interacting spin systems. As already pointed out by several authors a general understanding of the properties of entanglement in condensed matter systems may lead to a deeper comprehension of both dynamics and thermodynamics of many‐body systems. After a brief resume of known means to identify and quantify entanglement, we take interacting spins on a network as an example. We briefly discuss critical properties of entanglement, if the system undergoes a quantum phase transition, and some aspects of its dynamical behaviour.
On the axioms of topological electromagnetism
Authors: Delphenich D.H. 
Published: June 2022

AbstractThe axioms of topological electromagnetism that were given by Hehl, Obukhov, and Rubilar are refined by the use of geometrical and topological notions that are found on orientable manifolds. The central problem of defining the spacetime electromagnetic constitutive law in terms of the geometrical and topological structure of the spacetime manifold is elaborated upon in the linear and nonlinear cases. The manner by which the spacetime metric might follow from the electromagnetic constitutive law is examined in the linear case. The possibility that the intersection form of the spacetime manifold might play a role in defining a topological basis for a nonlinear electromagnetic constitutive law is explored. The manner by which electromagnetic wave motion relates to the geometric structure is also discussed.
Darboux transformation for two‐level system
Authors: Bagrov V. , Baldiotti M. , Gitman D. , Shamshutdinova V. 
Published: June 2022

AbstractWe develop the Darboux procedure for the case of the two‐level system. In particular, it is demonstrated that one can construct the Darboux intertwining operator that does not violate the specific structure of the equations of the two‐level system, transforming only one real potential into another real potential. We apply the obtained Darboux transformation to known exact solutions of the two‐level system. Thus, we find three classes of new solutions for the two‐level system and the corresponding new potentials that allow such solutions.
Magnetic impurities in small metal clusters
Authors: Pastor G.M. 
Published: June 2022

AbstractDedicated to Bernhard Mühlschlegel on the occasion of his 80th birthdayMagnetic impurities in small metallic clusters are investigated in the framework of the Anderson model by using exact diagonalization and geometry optimization methods.The singlet‐triplet spin gap ΔE shows a remarkable dependence as a function of band‐filling, cluster structure, and impurity position that can be interpreted in terms of the environment‐specific conduction‐electron spectrum. The low‐energy spin excitations involve similar energies as isomerizations. Interesting correlations between cluster structure and magnetic behavior are revealed. Finite‐temperature properties such as specific heat, effective impurity moment, and magnetic susceptibility are calculated exactly in the canonical ensemble. A finite‐size equivalent of the Kondo effect is identified and its structural dependence is discussed.
Mirage phenomena in superconducting quantum corrals
Authors: Schmid M. , Kampf A.P. 
Published: June 2022

AbstractDedicated to Bernhard Mühlschlegel on the occasion of his 80th birthdayWe investigate the local density of states and the order parameter structure inside an elliptic quantum corral on surfaces of isotropic and anisotropic superconductors. The Bogoliubov‐de Gennes equations are solved in the presence of non‐magnetic and magnetic impurities. We observe and discuss a variety of mirage and anti‐mirage phenomena, which specifically reflect the nature of the superconducting pairing state.
The Bose‐Hubbard model: from Josephson junction arrays to optical lattices
Authors: Bruder C. , Fazio R. , Schön G. 
Published: June 2022

AbstractDedicated to Bernhard Mühlschlegel on the occasion of his 80th birthdayThe Bose‐Hubbard model is a paradigm for the study of strongly correlated bosonic systems. We review some of its properties with emphasis on the implications on quantum phase transitions of Josephson junction arrays and quantum dynamics of topological excitations as well as the properties of ultra‐cold atoms in optical lattices.
Quasiparticles in transition metals with strong local correlations: band formation and collective effects
Authors: Grewe N. 
Published: June 2022

AbstractDedicated to Bernhard Mühlschlegel on the occasion of his 80th birthdayWe address the question, whether low lying one‐particle excitations in the Fermi‐liquid phase of highly correlated electron systems can form well defined bands of nearly stable quasiparticles, and comment on features of a universal band picture for these systems. We outline how to derive a description of instabilities to magnetic, charged ordered or superconducting phases, which bears a close analogy to Stoner theory and lends itself to an interpretation in terms of quasiparticle bands and residual interactions at low temperatures. Concepts and problems are illustrated via calculations for some standard models of solid‐state theory using modern many‐body techniques like NRG, NCA and DMFT. Differences to conventional band structure theory are pointed out. We shortly comment on the relevance of these questions to the physics of inhomogeneous systems and small particles.
Sound in biased piezoelectric materials of general anisotropy
Authors: Declercq N.F. , Degrieck J. , Leroy O. 
Published: June 2022

AbstractA theoretical model is presented that describes the propagation of sound in biased piezoelectric crystals of any kind of symmetry. The symmetry relations for the higher order material constants of trigonal 3m crystals, are calculated and listed in the appendix. The example of Lithium Niobate is highlighted, under influence of a bias pressure. The change of slowness (inverse velocity), because of this pressure, is calculated for every direction. Also the influence of stress on the acoustic polarization and the energy flow is outlined. Furthermore, the difference between the case where piezoelectricity is included and the case where it is omitted, is discussed. The description of changing slowness surfaces, because of a bias field, is not limited to homogeneous plane waves, but also inhomogeneous plane waves are taken into account.
Relativity and technology
Authors: Lämmerzahl C. 
Published: June 2022

AbstractIn this paper we first give a short outline of the principles and experimental status of tests of relativity, which indicates the huge still ongoing progress during the last years. Then emphasize is laid on the fact that relativity, either special or general, already enters a status of an applied technology in daily life. Examples are presented from positioning, metrology, earth sciences, and material sciences.
Cosmic black holes – from stellar to supramassive black holes in galaxies
Authors: Camenzind M. 
Published: June 2022

AbstractThe collapse of massive stars produces the most bizarre objects in the Universe. In the last ten years, astronomers have been successfully searching for real black holes in the Universe. Black hole astrophysics began in the 1960s with the discovery of quasars and other active galactic nuclei (AGN) in distant galaxies. Already in the 1960s it became clear that the most natural explanation for the quasar activity is the release of gravitational energy through accretion of gas onto supermassive black holes. The remnants of this activity have now been found in the centers of about 50 nearby galaxies. BH astrophysics received a new twist in the 1970s with the discovery of the X‐ray binary Cygnus X‐1. The X‐ray emitting compact object was too massive to be explained by a neutron star. Today, about 20 excellent BH candidates are known in XRBs. On the extragalactic scale, more than 100,000 quasars have been found in large galaxy surveys. At the redshift of the most distant ones, the Universe was younger than one billion year. The most enigmatic black hole candidates identified in the last years are the compact objects behind the Gamma‐Ray Bursters. The formation of all these types of black holes is accompanied by extensive emission of gravitational waves. The detection of these strong gravity events is one of the biggest challenges for physicists in the near future.
Quantum gravity: general introduction and recent developments
Authors: Kiefer C. 
Published: June 2022

AbstractI briefly review the current status of quantum gravity. After giving some general motivations for the need of such a theory, I discuss the main approaches in quantizing general relativity: Covariant approaches (perturbation theory, effective theory, and path integrals) and canonical approaches (quantum geometrodynamics, loop quantum gravity). I then address quantum gravitational aspects of string theory. This is followed by a discussion of black holes and quantum cosmology. I end with some remarks on the observational status of quantum gravity.
The supersymmetric vistas of the supergravity landscape
Authors: Ortín T. 
Published: June 2022

AbstractIn the recent times a lot of effort has been devoted to improve our knowledge about the space of string theory vacua (“the landscape”) in order to find statistical grounds to justify how and why the theory selects its vacuum. Particularly interesting are those vacua that preserve some supersymmetry, which are always supersymmetric solutions of some supergravity theory. We are going to review some recent results on the problem of finding all the supersymmetric solutions of a supergravity theory. We will also review some interesting solutions that have been discovered using these methods.
The revival of cosmic strings
Authors: Sakellariadou M. 
Published: June 2022

AbstractCosmic strings are one‐dimensional topological defects which could have been formed in the early stages of our Universe. They triggered a lot of interest, mainly for their cosmological implications: they could offer an alternative to inflation for the generation of density perturbations. It was shown however that cosmic strings lead to inconsistencies with the measurements of the cosmic microwave background temperature anisotropies. The picture has changed recently. It was shown that, on the one hand, cosmic strings can be generically formed in the framework of supersymmetric grand unified theories and that, on the other hand, cosmic superstrings could play the role of cosmic strings. There is also some possible observational support. All this led to a revival of cosmic strings research and this is the topic of my lecture.
Inflationary cosmology and braneworld scenarios
Authors: Lidsey J.E. 
Published: June 2022

AbstractCosmology has undergone a significant advance in recent years both observationally and theoretically. New high quality data from a host of Cosmic Microwave Background and high redshift surveys has provided strong support for the inflationary paradigm, which postulates that the universe expanded exponentially fast when it was a fraction of a second old. A key question that has arisen is the nature of the underlying physics that drove such a phase of accelerated expansion. An exciting theoretical development has been the realization that the standard model interactions may be confined to a four–dimensional brane, whereas gravitational interactions may also propagate through the extra dimensions. The radical proposal of the ‘braneworld scenario’ is that our observable universe is a brane embedded in a higher–dimensional bulk. We will review some of the recent developments in this field.
Cosmological scaling solutions (and their applications to string scenarios)
Authors: de Carlos B. 
Published: June 2022

AbstractIn this review we will study the phase space of cosmologies consisting of a scalar field with an exponential potential and a barotropic fluid. This is a very simple system which, however, gives rise to many interesting solutions that can be classified according to the values of the parameters in the game, namely those that define the type of fluid and the steepness of the potential. We shall then pay particular attention to scaling solutions, where the scalar energy density tracks that of the fluid.In the second part of this review we shall turn to specific models in order to apply the previous results. The goal is to study the dynamics of scalar fields in the Early Universe, and the framework to do so is different types of string compactifications. The corresponding scalar fields are then the so‐called moduli for which non perturbative potentials, of an exponential type, usually arise. We shall see how, contrary to previous expectations, the existence of scaling in this context allows these fields to dynamically stabilise at their tiny minima for a large fraction of initial conditions. This represents a further step in the quest for finding a suitable Particle Physics model compatible with the existing cosmology.
Universe scenarios from loop quantum cosmology
Authors: Bojowald M. 
Published: June 2022

AbstractLoop quantum cosmology is an application of recent developments for a non‐perturbative and background independent quantization of gravity to a cosmological setting. Characteristic properties of the quantization such as discreteness of spatial geometry entail physical consequences for the structure of classical singularities as well as the evolution of the very early universe. While the singularity issue in general requires one to use difference equations for a wave function of the universe, phenomenological scenarios for the evolution are based on effective equations implementing the main quantum modifications. These equations show generic bounces as well as inflation in diverse models, which have been combined to more complicated scenarios.
Time evolution of relativistic d + Au and Au + Au collisions
Authors: Wolschin G. , Biyajima M. , Mizoguchi T. , Suzuki N. 
Published: June 2022

AbstractThe evolution of charged‐particle production in collisions of heavy ions at relativistic energies is investigated as function of centrality in a nonequilibrium‐statistical framework. Precise agreement with recent d + Au and Au + Au data at = 200 GeV is found in a Relativistic Diffusion Model with three sources for particle production. Only the midrapidity source comes very close to local equilibrium, whereas the analyses of the overall pseudorapidity distributions show that the systems remain far from statistical equilibrium.
The posthumous impact of Paul Drude*
Authors: Cardona M. , Marx W. 
Published: June 2022

AbstractIn this study the long‐term impact of the works of Paul Drude has been analyzed by bibliometric methods. His overall citation impact and rank within the pre‐1910 authors in chemistry and physics has been determined. The time‐dependent number of mentions of his name, the overall citation impact and the citation numbers of single articles and books have been investigated. The impact time curves of his most frequently cited articles and books are presented and discussed. The scientific contributions of the most influential Drude works for solid state physics are analyzed, in particular their impact on recent research.
Ionics versus electronics, and the general case of mixed conductor *
Authors: Maier J. 
Published: June 2022

AbstractThe article emphasizes the importance of ion transport for solid state physics in view of the significance of ionic charge carriers for compositional changes and electrochemical applications, but also in view of their importance for defining the electronic charge carrier density. Special emphasis is given (i) to the mixed conductor as the general case which encompasses the pure electronic conductor and the pure ionic conductor as special cases, (ii) to the bridge between high temperature and room temperature situation and (iii) to the modern fields of interfacial ion transport and nano‐ionics.
Anomalous Hall effect in ferromagnetic disordered metals *
Authors: Wölfle P. , Muttalib K.A. 
Published: June 2022

AbstractThe anomalous Hall effect in disordered band ferromagnets is considered in the framework of quantum transport theory. A microscopic model of electrons in a random potential of identical impurities including spin‐orbit coupling is used. The Hall conductivity is calculated from the Kubo formula for both, the skew scattering and the side‐jump mechanisms. The recently discussed Berry phase induced Hall current is also evaluated within the model. The effect of strong impurity scattering is analyzed and it is found to affect the ratio of the non‐diagonal (Hall) and diagonal components of the conductivity as well as the relative importance of different mechanisms.
The Drude model in correlated systems *
Authors: Degiorgi L. 
Published: June 2022

AbstractThe Drude model provides a useful phenomenological approach for the discussion of the metallic properties in conducting materials, particularly from the perspective of their electrodynamic response. We first introduce the model and its generalization, which accounts for the frequency dependence of the scattering rate and effective mass of the quasiparticles. Three selected examples, from the optical research on the topic of strongly correlated metals, will illustrate the variety of issues and broad spectrum of informations, which can be addressed and achieved within this approach.
Eigentensors of the Lichnerowicz operator in Euclidean Schwarzschild metrics*
Authors: Martínez‐Morales J.L. 
Published: June 2022

AbstractProperties of the eigentensors of the Lichnerowicz Laplacian for the Euclidean Schwarzschild metric are discussed together with possible applications to the linear stability of higher‐dimensional instantons. The main statement of the article is that any eigentensor of the Lichnerowicz operator in a Euclidean (possibly higher‐dimensional) Schwarzschild metric is essentially singular at infinity.