Spacetime Dimensions Research Articles

МУЗЕИ МАЛЫХ ГОРОДОВ РОССИИ: ОСОБЕННОСТИ МЕДИАЦИИ ЛОКАЛЬНОЙ ИСТОРИИ

The museum functions as an institution of memory, constructing images of the past and transmitting them to new generations. They are based on scientific ideas, social order and visitor requests, i.e. they differ from historical reality. This process is defined by the term “mediation”, which correlates with the concepts of “communication” and “interpretation”. Taking into account the specifics of the museum (historical, memorial, art), the features of mediation, the images of the past have their own differences and complement each other, constructing a unique image of the place. A special role in this process is played by local history museums aimed at comprehensive modeling and presentation of the local past. The image of the local history created by historical museums is reflected in the exposition and has some specifics. It has a space-time dimension, often supplemented by “action” (interactivity), and is also characterized by abstractness and conventionality, which is directly related to the language of description (scientific and / or literary). The current trend is characterized by active visualization and mythologization of the historical image, which is especially typical for museums in small towns. The article is based on the materials of a historical and sociological survey of 12 small towns in Russia using interview, observation, mind map methods (RSF grant No. 21-18-00418 “Museum of a small town. Tthe multiplicity of cultures of memory”). The program included the study of not only museums (state, municipal, school, home, folk, private), but also archives, libraries, media, i.e. all institutions of memory. Such an integrated approach made it possible to clarify the specifics of the museum “genre” of memorization.

Flow As An Operative Methodology Generating The Time Of Intersection Through The Relationship Between Architecture And Artwork In Public Space

Time has always fascinated men for its (apparently) inviolable structure and for the poetic dimension that this concept brings with it. During the history of civilization, time has been a crucial concept to understanding reality. At the beginning of the Twentieth century, thanks to the scientific discoveries, above all, Albert Einstein’s general relativity theory, the notion of time became an important element also for science for understanding the structure of the universe. The continuous and ever-faster scientific discoveries have also dissolved the linearity of time and its very nature, offering new possibilities to rethink space-time, as a series of connected, but not necessarily linear, events. Something we are experiencing today through the multi-temporality of the digital world, but which at the same time also shifts our way of perceiving physical reality.Everything we do and produce is inevitably part of a space-time dimension. We can therefore interpret time - also - as a distinctive structural element of the things that human beings build, whether small or large, from tools to metropolises.In this background, it is very interesting to understand how time works in two of the most symbolic categories of objects of human creation, art, and architecture, focusing more specifically on the category of art in public space. The time that works into the artwork is naturally different from the time that works into architecture, that is, observing art in public space, there are two different times that overlap, or rather the architectural space (and time) houses inside of it, the space (and time) of the work of art. The overlapping of these two different times, inevitably creates a third time, that we will call a “Time of Intersection”, which becomes the subject of this paper.

Geometric action for extended Bondi-Metzner-Sachs group in four dimensions

The constrained Hamiltonian analysis of geometric actions is worked out before applying the construction to the extended Bondi-Metzner-Sachs group in four dimensions. For any Hamiltonian associated with an extended BMS4 generator, this action provides a field theory in two plus one spacetime dimensions whose Poisson bracket algebra of Noether charges realizes the extended BMS4 Lie algebra. The Poisson structure of the model includes the classical version of the operator product expansions that have appeared in the context of celestial holography. Furthermore, the model reproduces the evolution equations of non-radiative asymptotically flat spacetimes at null infinity.

Hubbard Bands, Mott Transition and Deconfinement in Strongly Correlated Systems

The problem of deconfinement phases in strongly correlated systems is discussed. In space–time dimension d = 3 + 1, a competition of confinement and Coulomb phases occurs, but in d = 2 + 1 the confining phase dominates owing to monopole proliferation, but Dirac points can change the situation. Combining the Kotliar–Ruckenstein representation and fractionalized spin-liquid deconfinement picture, the Mott transition and Hubbard subbands are treated, general expressions in the case of an arbitrary bare band spectrum being obtained. The transition into a metallic state is determined by condensation of a gapless boson mode. The spectrum picture in the insulating state is considerably influenced by the spinon spin-liquid spectrum and hidden Fermi surface.

Higher derivative corrections to black brane thermodynamics and the weak gravity conjecture

We study higher derivative corrections to black brane thermodynamics and their implications for the weak gravity conjecture for p-form gauge fields. In particular we show that higher derivative corrections decrease tension-to-charge ratios of extremal black branes as implied by the weak gravity conjecture, if four-derivative couplings follow scattering positivity bounds. We also demonstrate that entropy corrections in the micro canonical ensemble are positive under the same assumptions. This extends earlier works in the Einstein-Maxwell theory to p-form gauge fields in general spacetime dimensions.

Popcorn Drude weights from quantum symmetry

Integrable models provide emblematic examples of non-ergodic phenomena. One of their most distinguished properties are divergent zero-frequency conductivities signalled by finite Drude weights. Singular conductivities owe to long-lived quasiparticle excitations that propagate ballistically through the system without any diffraction. The case of the celebrated quantum Heisenberg chain, one of the best-studied many-body paradigms, turns out to be particularly mysterious. About a decade ago, it was found that the spin Drude weight in the critical phase of the model assumes an extraordinary, nowhere continuous, dependence on the anisotropy parameter in the shape of a ‘popcorn function’. This unprecedented discovery has been afterwards resolved at the level of the underlying deformed quantum symmetry algebra which helps explaining the erratic nature of the quasiparticle spectrum at commensurate values of interaction anisotropy. This work is devoted to the captivating phenomenon of discontinuous Drude weights, with the aim to give a broader perspective on the topic by revisiting and reconciling various perspectives from the previous studies. Moreover, it is argued that such an anomalous non-ergodic feature is not exclusive to the integrable spin chain but can be instead expected in a number of other integrable systems that arise from realizations of the quantum group , specialized to unimodular values of the quantum deformation parameter q. Our discussion is framed in the context of gapless anisotropic quantum chains of higher spin and the sine-Gordon quantum field theory in two space-time dimensions.

Nonperturbative bounds on scattering of massive scalar particles in d ≥ 2

We study two-to-two scattering amplitudes of a scalar particle of mass m. For simplicity, we assume the presence of ℤ2 symmetry and that the particle is ℤ2 odd. We consider two classes of amplitudes: the fully nonperturbative ones and effective field theory (EFT) ones with a cut-off scale M. Using the primal numerical method which allows us to impose full non-linear unitarity, we construct novel bounds on various observables in 2 ≤ d ≤ 4 space-time dimensions for both classes of amplitudes. We show that our bounds are much stronger than the ones obtained by using linearized unitarity or positivity only. We discuss applications of our bounds to constraining EFTs. Finally, we compare our bounds to the amplitude in ϕ4 theory computed perturbatively at weak coupling, and find that they saturate the bounds.

The fate of infrared divergences in a finite formulation of field theory: QED revisited

Within the framework of the recently proposed Taylor–Lagrange regularization procedure, we reanalyze the calculation of radiative corrections in quantum electrodynamics (QED) at next to leading order. Starting from a well-defined local bare Lagrangian, the use of this regularization procedure enables us to manipulate fully finite elementary amplitudes in the ultra-violet (UV) as well as infrared (IR) regimes, in physical [Formula: see text] space–time dimensions and for physical massless photons, as required by gauge invariance. We can thus separately calculate the electromagnetic form factors of the electron and the cross-section for real photon emission, each quantity being finite in these physical conditions. We then discuss the renormalization group (RG) equations within this regularization procedure. Thanks to the taming of IR divergencies, the RG equation associated to the (physical) effective charge exhibits an UV stable fixed point at [Formula: see text], showing an asymptotic freedom-type behavior. We finally consider the case of two mass scales, one low and one heavy, paying particular attention to the natural decoupling properties between heavy and light degrees of freedom. As a direct consequence, the fine structure constant should be zero in the limit of massless electrons.

Cohen-Macaulay Property of Feynman Integrals

The connection between Feynman integrals and GKZ A-hypergeometric systems has been a topic of recent interest with advances in mathematical techniques and computational tools opening new possibilities; in this paper we continue to explore this connection. To each such hypergeometric system there is an associated toric ideal, we prove that the latter has the Cohen-Macaulay property for two large families of Feynman integrals. This implies, for example, that both the number of independent solutions and dynamical singularities are independent of space-time dimension and generalized propagator powers. Furthermore, in particular, it means that the process of finding a series representation of these integrals is fully algorithmic.

A handbook of holographic 4-point functions

We present a comprehensive discussion of tree-level holographic 4-point functions of scalar operators in momentum space. We show that each individual Witten diagram satisfies the conformal Ward identities on its own and is thus a valid conformal correlator. When the β = ∆ − d/2 are half-integral, with ∆ the dimensions of the operators and d the spacetime dimension, the Witten diagrams can be evaluated in closed form and we present explicit formulae for the case d = 3 and ∆ = 2, 3. These correlators require renormalization, which we carry out explicitly, and lead to new conformal anomalies and beta functions. Correlators of operators of different dimension may be linked via weight-shifting operators, which allow new correlators to be generated from given ‘seed’ correlators. We present a new derivation of weight-shifting operators in momentum space and uncover several subtleties associated with their use: such operators map exchange diagrams to a linear combination of exchange and contact diagrams, and special care must be taken when renormalization is required.

Chiral Approach to Massive Higher Spins.

We propose a new, chiral description for massive higher-spin particles in four spacetime dimensions, which facilitates the introduction of consistent interactions. As proof of concept, we formulate three theories, in which higher-spin matter is coupled to electrodynamics, non-Abelian gauge theory, or gravity. The theories are chiral and have simple Lagrangians, resulting in Feynman rules analogous to those of massive scalars. Starting from these Feynman rules, we derive tree-level scattering amplitudes with two higher-spin matter particles and any number of positive-helicity photons, gluons, or gravitons. The amplitudes reproduce the arbitrary-multiplicity results that were obtained via on-shell recursion in a parity-conserving setting, and which chiral and nonchiral theories thus have in common. The presented theories are currently the only examples of consistent interacting field theories with massive higher-spin fields.

Echoes from braneworld wormholes

We have studied the stability of wormhole geometries, under massless scalar, electromagnetic and axial gravitational perturbations, in the context of higher dimensional spacetimes. Intriguingly, the construction of a wormhole spacetime in the presence of higher dimensions, known as braneworld wormholes, \emph{does not} require the existence of exotic matter fields, unlike the scenario in four spacetime dimensions. Being a nonvacuum spacetime, the effective potential experienced by the axial gravitational perturbation differs considerably from the scenarios involving black holes. In particular, the present work provides one of the first attempts to study the gravitational perturbations of the wormhole spacetimes. Our analysis, involving both analytical and numerical techniques, demonstrates that there are echoes in the time domain signal of all the perturbations and the echo time delay is intimately related to the parameters originating from higher dimensions. Thereby combining the attempt to search for wormholes and extra dimensions, with the existence of gravitational wave echoes. Implications and future directions have also been discussed.

A single-particle framework for unitary lattice gauge theory in discrete time

We construct a real-time lattice-gauge-theory (LGT)-type action for a spin-1/2 matter field of a single particle on a -dimensional spacetime lattice. The framework is based on a discrete-time quantum walk, and is hence inherently unitary and strictly local, i.e. transition amplitudes exactly vanish outside of a lightcone on the lattice. We then provide a lattice Noether’s theorem for internal symmetries of this action. We further couple this action to an electromagnetic field by a minimal substitution on the lattice. Finally, we suggest a real-time LGT-type action for the electromagnetic field in arbitrary spacetime dimensions, and derive its classical equations of motion, which are lattice versions of Maxwell’s equations.

Chirality distributions inside baryons in QCD2

The connection between the spin distribution and the topological structure of the baryon is an open and important problem. Here we address it using QCD in $(1+1)$ spacetime dimensions, which is exactly solvable at large number of colors $N$. It is found that the distribution of chirality inside a baryon is drastically different from a chirality distribution inside states with zero baryon number, ``mesons". This difference is shown to arise from the topological structure of the baryon -- at large $N$, all of the baryon's chirality is concentrated near $x=0$, whereas in a meson state it vanishes in the small $x$ limit. Our results illustrate how the constituent features of the baryon reemerge and are tied to the topological features of the bosonized solitonic solution. Possible implications for QCD in $(3+1)$ dimensions and for deep inelastic scattering experiments are discussed.

Asymptotic structure of Carrollian limits of Einstein-Yang-Mills theory in four spacetime dimensions

In this paper, three things are done. First, we study from an algebraic point of view the infinite-dimensional Bondi-Metzner-Sachs (BMS)-like extensions of the Carroll algebra relevant to the asymptotic structure of the electric and magnetic Carrollian limits of Einstein gravity. In the course of this study we exhibit by the ``Carroll-Galileo duality'' a new infinite-dimensional BMS-like extension of the Galilean algebra and of its centrally extended Bargmann algebra. Second, we consider the electric Carrollian limit of the pure Einstein theory and indicate that more flexible boundary conditions than the ones that follow from just taking the limit of the Einsteinian boundary conditions are actually consistent. These boundary conditions lead to a bigger asymptotic symmetry algebra that involves spatial supertranslations depending on three functions of the angles (instead of one). Third, we turn to the Carrollian limit of the coupled Einstein-Yang-Mills system. An infinite-dimensional color enhancement of the gauge algebra is found in the electric Carrollian limit of the Yang-Mills field, which allows angle-dependent Yang-Mills transformations at spatial infinity, not available in the Einstein-Yang-Mills case prior to taking the Carrollian electric limit. This enhancement does not occur in the magnetic limit.

Nonperturbative Double Copy in Flatland

We derive a nonperturbative, Lagrangian-level formulation of the double copy in two spacetime dimensions. Our results elucidate the field theoretic underpinnings of the double copy in a broad class of scalar theories which can include masses and higher-dimension operators. An immediate corollary is the amplitudes-level double copy at all orders in perturbation theory. Applied to certain integrable models, the double copy defines an isomorphism between Lax connections, Wilson lines, and infinite towers of conserved currents. We also implement the double copy at the level of nonperturbative classical solutions, both analytically and numerically, and present a generalization of the double copy map that includes a fixed tower of higher-dimension corrections given by the Moyal algebra.

Critique of the use of geodesics in astrophysics and cosmology

Since particles obey wave equations, in general one is not free to postulate that particles move on the geodesics associated with test particles. Rather, for this to be the case one has to be able to derive such behavior starting from the equations of motion that the particles obey, and to do so one can employ the eikonal approximation. To see what kind of trajectories might occur we explore the domain of support of the propagators associated with the wave equations, and extend the results of some previous propagator studies that have appeared in the literature. For a minimally coupled massless scalar field the domain of support in curved space is not restricted to the light cone, while for a conformally coupled massless scalar field the curved space domain is only restricted to the light cone if the scalar field propagates in a conformal to flat background. Consequently, eikonalization does not in general lead to null geodesics for curved space massless rays even though it does lead to straight line trajectories in flat spacetime. Equal remarks apply to the conformal invariant Maxwell equations. However, for massive particles one does obtain standard geodesic behavior this way, since they do not propagate on the light cone to begin with. Thus depending on how big the curvature actually is, in principle, even if not necessarily in practice, the standard null-geodesic-based gravitational bending formula and the general behavior of propagating light rays are in need of modification in regions with high enough curvature. We show how to appropriately modify the geodesic equations in such situations. We show that relativistic eikonalization has an intrinsic light-front structure, and show that eikonalization in a theory with local conformal symmetry leads to trajectories that are only globally conformally symmetric. Propagation of massless particles off the light cone is a curved space reflection of the fact that when light travels through a refractive medium in flat spacetime its velocity is modified from its free flat spacetime value. In the presence of gravity spacetime itself acts as a medium, and this medium can then take light rays off the light cone. This is also manifest in a conformal invariant scalar field theory propagator in two spacetime dimensions. It takes support off the light cone, doing so in fact even if the geometry is conformal to flat. We show that it is possible to obtain eikonal trajectories that are exact without approximation, and show that normals to advancing wavefronts follow these exact eikonal trajectories, with these trajectories being the trajectories along which energy and momentum are transported. In general then, in going from flat space to curved space one does not generalize flat space geodesics to curved space geodesics. Rather, one generalizes flat space wavefront normals (normals that are geodesic in flat space) to curved space wavefront normals, and in curved space normals to wavefronts do not have to be geodesic.

Nonminimal non-Abelian quantum vector fields in curved spacetime

The quantum effective action of non-minimal vector fields with Abelian or non-Abelian gauge degrees of freedom in curved spacetime is studied. The Proca or Yang-Mills fields are coupled to a local mass-like term acting in both coordinate and gauge spaces. Pathologies due to gauge invariance in the ultraviolet are avoided through the introduction of a non-Abelian version of the Stueckelberg field. It is found that the breaking of gauge invariance induced by the mass term affects only the tree level part of the effective action. The ultraviolet divergent part of the effective action to one loop is obtained using the method of covariant symbols and dimensional regularization. Formulas are given valid for any spacetime dimension and explicit results are shown for the two-dimensional case. As already happened for a single vector field, the ultraviolet divergences are local but not of polynomial type.

Renormalization of supersymmetric chiral theories in rational spacetime dimensions

We renormalize models with scalar chiral superfields with an odd superpotential to several orders in perturbation theory. These extensions of the cubic Wess–Zumino model are renormalizable in spacetime dimensions which are rational. When endowed with an O(N) symmetry it is shown that they share the same property as their non-supersymmetric counterparts in that at a particular fixed point there is an emergent OSp(1|n-1) symmetry, where n is the power of the superpotential. This is shown at a loop order beyond that for which it was established in the parallel non-supersymmetric theory.

Strange Quark Star (SQS) in Tolman IV potential with density dependent B-parameter and charge

In this paper, the solutions of Einstein–Maxwell Field Equations for relativistic strange quark star in Tolman-IV potential considering MIT bag model EoS p=frac{1}{3}(rho -4B) of interior matter in presence of charge in higher dimensions is presented, where B is bag parameter. Here we consider density dependent B as it has more practical application. We note some interesting results. It is observed that interior of a strange quark star may contain bulk stable quarks as a whole having energy per baryon E_B<930.4 MeV/fm^3 or stable quark matter core enclosed by a thin metastable quark matter layer enveloped by unstable quark matter. It is also found that interior composition depends on the value of space-time dimension (D) and net charge (Q). The model presented in this paper satisfies all the necessary stability and energy conditions for a viable stellar configuration. We also note the maximum mass of stable strange quark star is 1.773 M_{odot } for density dependent B and 1.684 M_{odot } for constant B.