Particle Creation Research Articles

Schwinger pair creation for monolayer graphene in a constant electromagnetic field, and in noncommutative phase space coordinates

In this paper, we study the creation of particles from the vacuum in monolayer graphene by an electromagnetic field in a noncommutative (NC) phase space coordinate considering the Schwinger method. For two different gauges, the probability of particle creation is calculated using the effective action, and special cases are considered. The essential result is that the noncommutativity of the phase space contributes to the effective action and consequently it has an influence on the process of pair creation from the vacuum.

Wave correlations and quantum noise in cosmology

Wave noise is correlated. While it may look random in space, correlations appear in space–time, because the noise is carried by wave propagation. These correlations of wave noise give rise to fluctuation forces such as the Casimir force, they are responsible for the particle creation in the dynamical Casimir effect and in the expanding Universe. This paper considers the noise correlations for light waves in non-exponentially expanding flat space. The paper determines the high-frequency asymptotics of the correlation spectrum in the conformal vacuum. These noise correlations give rise to a nontrivial vacuum energy that may appear as the cosmological constant.

Stochastic Particle Creation: From the Dynamical Casimir Effect to Cosmology

We study a stochastic version of the dynamical Casimir effect, computing the particle creation inside a cavity produced by a random motion of one of its walls. We first present a calculation perturbative in the amplitude of the motion. We compare the stochastic particle creation with the deterministic counterpart. Then, we go beyond the perturbative evaluation using a stochastic version of the multiple scale analysis, that takes into account stochastic parametric resonance. We stress the relevance of the coupling between the different modes induced by the stochastic motion. In the single-mode approximation, the equations are formally analogous to those that describe the stochastic particle creation in a cosmological context, that we rederive using multiple scale analysis.

The Dual Role of Oxidative-Stress-Induced Autophagy in Cellular Senescence: Comprehension and Therapeutic Approaches.

The contemporary lifestyle of the last decade has undeniably caused a tremendous increase in oxidative-stress-inducing environmental sources. This phenomenon is not only connected with the rise of ROS levels in multiple tissues but is also associated with the induction of senescence in different cell types. Several signaling pathways that are associated with the reduction in ROS levels and the regulation of the cell cycle are being activated, so that the organism can battle deleterious effects. Within this context, autophagy plays a significant role. Through autophagy, cells can maintain their homeostasis, as if it were a self-degradation process, which removes the "wounded" molecules from the cells and uses their materials as a substrate for the creation of new useful cell particles. However, the role of autophagy in senescence has both a "dark" and a "bright" side. This review is an attempt to reveal the mechanistic aspects of this dual role. Nanomedicine can play a significant role, providing materials that are able to act by either preventing ROS generation or controllably inducing it, thus functioning as potential therapeutic agents regulating the activation or inhibition of autophagy.

Motion by Mean Curvature from Glauber-Kawasaki Dynamics with Speed Change

We derive a continuum mean-curvature flow as a certain hydrodynamic scaling limit of Glauber-Kawasaki dynamics with speed change. The Kawasaki part describes the movement of particles through particle interactions. It is speeded up in a diffusive space-time scaling. The Glauber part governs the creation and annihilation of particles. The Glauber part is set to favor two levels of particle density. It is also speeded up in time, but at a lesser rate than the Kawasaki part. Under this scaling, a mean-curvature interface flow emerges, with a homogenized `surface tension-mobility' parameter reflecting microscopic rates. The interface separates the two levels of particle density. Similar hydrodynamic limits have been derived in two recent papers; one where the Kawasaki part describes simple nearest neighbor interactions, and one where the Kawasaki part is replaced by a zero-range process. We extend the main results of these two papers beyond nearest-neighbor interactions. The main novelty of our proof is the derivation of a `Boltzmann-Gibbs' principle which covers a class of local particle interactions.

The 𝒫(𝜑)₂ Model on de Sitter Space

In 1975 Figari, Høegh-Krohn and Nappi constructed theP(φ)2{\mathscr P}(\varphi )_2model on the de Sitter space. Here we complement their work with new results, which connect this model to various areas of mathematics. In particular, i.) we discuss the causal structure of de Sitter space and the induces representations of the Lorentz group. We show that the UIRs ofSO0(1,2)SO_0(1,2)for both the principal and the complementary series can be formulated on Hilbert spaces whose functions are supported on a Cauchy surface. We describe the free classical dynamical system in both its covariant and canonical form, and present the associated quantum one-particle KMS structures in the sense of Kay (1985). Furthermore, we discuss the localisation properties of one-particle wave functions and how these properties are inherited by the algebras of local observables.ii.) we describe the relations between the modular objects (in the sense of Tomita-Takesaki theory) associated to wedge algebras and the representations of the Lorentz group. We connect the representations of SO(1,2) to unitary representations ofSO(3)SO(3)on the Euclidean sphere, and discuss how theP(φ)2{\mathscr P}(\varphi )_2interaction can be represented by a rotation invariant vector in the Euclidean Fock space. We present a novel Osterwalder-Schrader reconstruction theorem, which shows that physicalinfrared problemsare absent on de Sitter space. As shown in Figari, Høegh-Krohn, and Nappi (1975), the ultraviolet problems are resolved just like on flat Minkowski space. We state the Haag–Kastler axioms for theP(φ)2{\mathscr P}(\varphi )_2model and we explain how thegeneratorsof the boosts and the rotations for the interacting quantum field theory arise from thestress-energy tensor. Finally, we show that the interacting quantum fields satisfy theequations of motionin their covariant form. In summary, we argue that the de SitterP(φ)2{\mathscr P}(\varphi )_2model is the simplest and most explicit relativistic quantum field theory, which satisfies basic expectations, like covariance, particle creation, stability and finite speed of propagation.

From the Hubble Constant to the Black Hole Model. Universe Expansion with Matter Creation and a New Perspective on Dark Energy Observations

From the Hubble Constant to the Black Hole Model. Universe Expansion with Matter Creation and a New Perspective on Dark Energy Observations

Bioinspired Jellyfish Microparticles from Microfluidics.

Nonspherical particles have attracted increasing interest because of their shape anisotropy. However, the current methods to prepare anisotropic particles suffer from complex generation processes and limited shape diversity. Here, we develop a piezoelectric microfluidic system to generate complex flow configurations and fabricate jellyfish-like microparticles. In this delicate system, the piezoelectric vibration could evolve a jellyfish-like flow configuration in the microchannel and the in situ photopolymerization could instantly capture the flow architecture. The sizes and morphologies of the particles are precisely controlled by tuning the piezoelectric and microfluidic parameters. Furthermore, multi-compartmental microparticles with a dual-layer structure are achieved by modifying the injecting channel geometry. Moreover, such unique a shape endows the particles with flexible motion ability especially when stimuli-responsive materials are incorporated. On the basis of that, we demonstrate the capability of the jellyfish-like microparticles in highly efficient adsorption of organic pollutants under external control. Thus, it is believed that such jellyfish-like microparticles are highly versatile in potential applications and the piezoelectric-integrated microfluidic strategy could open an avenue for the creation of such anisotropic particles.

Fabrication of Aluminum 5083/SiC Surface Composite on Tungsten Inert Gas Weld Joint by Novel Direct Friction Stir Processing Technique

For the creation of surface reinforcement particles in the metal matrix, friction stir processing is frequently utilized. Formation of aluminum/SiC surface composite on Tungsten Inert Gas (TIG) butt weld of Al5083 by a novel technique of direct friction stir processing (DFSP) using a hollow tool is successfully demonstrated in this present work. Deposition of SiC in the stir zone of DFSP was confirmed by X-Ray diffraction (XRD) method. Micro analysis of weld joint was achieved using metallographic microscope and scanning electron microscope (SEM). Microstructure of stir zone of DFSP shows finely distributed SiC reinforcement particles in aluminum matrix. Absence of detrimental intermetallics was confirmed by energy dispersive spectroscopy (EDS) analysis. Tensile strength of DFSPed specimen was found to be 227.3 MPa which is 19.5% lower than UTS of autogenous TIG weld specimen. Microhardness of SZ of DFSP was found to be increased from TIG weld microhardness of 86 Hv to 107 Hv due to presence of SiC particles.

Global stability of a delayed HIV-1 dynamics model with saturation response with cure rate, absorption effect and two time delays

In this paper, we proposed a new HIV-1 infection model with saturation infection rate by incorporating, cure rate, absorption effect, and two-time delays namely intracellular time delay that representing the time viral passage into a target cell and creation of new infectious particles and maturation time delay representing the required time for newly produce virus to mature and the infect the susceptible cell. The mathematical investigation shows that the basic reproduction number R0 of the model totally decides the steadiness properties. Utilizing the characteristic equation of the model and Routh-Hurwitz steadiness basis, we affirmed that the infection-free equilibrium and the chronic disease equilibrium are locally asymptotically steady in case R0 ≤ 1 and R0 > 1, individually. If R0 ≤ 1, using the appropriate Lyapunov functions and LaSalle’s invariance principle, it has been shown that the infection-free equilibrium of the model is globally asymptotically stable. If R0 > 1 the model is persistent. Conversely, if R0 > 1, the infection-free equilibrium is unstable and a unique chronic infection equilibrium exists. We show that, if R0 > 1, the chronic infection is globally asymptotically stable. Moreover, numerical simulations are performed to verify the theoretical results.

Design and synthesis of unnatural coordination glycopolymer particles (CGPs): unleashing the potential of catechol-saccharide derivatives.

Our study unveils an innovative methodology that merges catechols with mono- and disaccharides, yielding a diverse array of compounds. This strategic fusion achieves robust yields and introduces ligands with a dual nature: encompassing both the chelating attributes of catechols and the recognition capabilities of carbohydrates. This synergistic design led us to couple one of the novel ligands with an Fe(iii) salt, resulting in the creation of Coordination Glycopolymer Particles (CGPs). These CGPs demonstrate remarkable qualities, boasting outstanding dispersion in both aqueous media and Phosphate Buffered Saline (PBS) solution (pH ∼7.4) at higher concentrations (0.26 mg μL-1). Displaying an average Z-size of approximately 55 nm and favourable polydispersity indices (<0.25), these particles exhibit exceptional stability, maintaining their integrity over prolonged periods and temperature variations. Notably, they retain their superior dispersion and stability even when subjected to freezing or heating to 40 °C, making them exceptionally viable for driving biological assays. In contrast to established methods for synthesizing grafted glycopolymers, where typically a glycopolymer is doped with catechol derivatives to create synergy between chelating properties and those inherent to the saccharide, our approach provides a more efficient and versatile pathway for generating CGPs. This involves combining catechols and carbohydrates within a single molecule, enabling the fine-tuning of organic structure from a monomer design step and subsequently transferring these properties to the polymer.

К конструированию энтропийно–силовой модели расширения Вселенной, обусловленного гравитационно-индуцированным производством темной материи и влиянием обменной энтропии на событийном горизонте

Within the framework of Prigogin's gravitational theory of the geometry-matter connection that ensures the production of particles in a cosmological fluid, a single-fluid model of the evolution of a spatially flat, homogeneous and isotropic Universe is thermodynamically constructed. In order to obtain it, the continuity equation (energy conservation equation) was derived from the first law of thermodynamics taking into account the gravity-induced creation of matter and energy exchange processes on the visible horizon of the Universe. Based on this equation and the fundamental Friedman equation describing the expansion of the Universe, in the context of the entropic formalitу modified Friedman-Robertson-Walker equations were constructed to model various scenarios of the evolution of the flat Universe with matter production. In their derivation, several forms of exchangeable phenomenological entropies associated by assumption with the region of the visible cosmological horizon were used. The resulting generalized Prigogine model agrees well with the standard cosmological ?-model for cold dark matter and allows us to explain the accelerated expansion of the late Universe, providing its cosmological history without the introduction of new fields.

Challenging \(\Lambda \)CDM with Scalar-tensor \(f(R,T)\) Gravity and Thermodynamics of Irreversible Matter Creation

Challenging \(\Lambda \)CDM with Scalar-tensor \(f(R,T)\) Gravity and Thermodynamics of Irreversible Matter Creation

Inconsistency of General Relativity Predictions for the Universe Expansion vs. the Black Hole Model

A consistency argument proves that the General Relativity predictions of a time power law decelerated Universe expansion in the matter dominated era to be untenable by more than an order of magnitude. This questions the usual matter conservation law and supports the black hole approach which predicts continuous matter creation for the expanding black hole we are living in. The role of homogeneity in the equations for gravity and its consequences in this respect are discussed. Further arguments in favour of the black hole model are presented.

Particle production in a rainbow background

The present study aims to investigate the particle creation process originating from electromagnetic and gravitational fields of the scalar and spin-1/2 particles in the rainbow formalism of general relativity. In this context, an external electric field decreasing with time for the anisotropic Bianchi I-type rainbow metric is considered. The number density of the created particles is obtained for both Klein–Gordon and Dirac particles. The obtained results were evaluated graphically.

Perturbative understanding of nonperturbative processes and quantumization versus classicalization

In some instances of study of quantum evolution of classical backgrounds it is considered inevitable to resort to nonperturbative methods at the price of treating the system semiclassically. We show that a fully quantum perturbative treatment, in which the background is resolved as a multiparticle state, recovers the semiclassical nonperturbative results and allows going beyond. We reproduce particle creation by a classical field in a theory of two scalars as well as in scalar QED in terms of scattering processes of high multiplicity. The multiparticle treatment also gives a transparent picture of why a single-process transition from a classical to a quantum state, which we call quantumization, is exponentially suppressed, whereas the opposite process, classicalization, can take place swiftly if the microstate degeneracy of the classical state is high. An example is provided by the $N$-graviton portrait of a black hole: a black hole can form efficiently via a $2\ensuremath{\rightarrow}N$ classicalization process in the collision of high-energy particles, but its quantumization via a decay $N\ensuremath{\rightarrow}2$ is exponentially suppressed.

Microwave synthesized erbium vanadate nano-photocatalyst: Application for enhanced degradation of contaminated water

The subject of treatment of real or synthetic industrial effluents and photocatalysts has concerned a lot of consideration from scientists. Among the diverse metal oxide photocatalytic materials, the narrow bandgap compounds are of superior significance owing to appropriate efficiency in the optical application. In this work, we produced pristine ErVO4 through the microwave-assisted synthesis method. Diverse solvents and different power intensities have been employed in this preparation for size controlling and shape engineering, such as Ethylene glycol (EG), Propylene glycol (PG), and Polyethylene glycol (PEG-400) and power of 900, 750 and 600 W. XRD, FT-IR, and EDS analysis have been utilized to demonstrate the phase purity, and FE-SEM and TEM were employed to discover the shape of resultant ErVO4. The several attributes of the samples, such as the surface area, magnetic and optical features, were inquired by BET, VSM and DRS techniques, correspondingly. Microwave power of 900 W and Ethylene glycol solvent was selected as an optimal condition owing to the creation of uniform nanosized particles. So nanostructured ErVO4 was operated as a catalyst for the decolorization of colored pollutants (Erythrosine (ER), Methyl Orange (MO), and methylene blue (MB)). According to the discoveries, the MB with higher photocatalytic efficiency was compared in different dye concentrations and catalyst loading experiments to attain ideal performance.

COSMOLOGICAL CONCEPT OF ST. GREGORY OF NYSSA

The article discusses the concept of the creation of the universe according to St. Gregory of Nyssa (Cappadocian). This theme was in sharp contrast to ancient Greek philosophy, which was characterized by ontological diarchy. The problem that Gregory of Nyssa discusses is related to the creation of matter, how the matter acquire substantia and hypostasis from nothingness. According to Gregory, God creates all the properties that characterize matter, and their connection determines the existence of different elements. Also noteworthy is the dynamic of the universe, which means that the universe was not originally perfect. It is about the causal creation or properties of creatures, which are followed by the dynamic development of creatures in time. A special place is given to the creation of man - the crown of the universe. Initially humanity is formed and only later does a sexual difference occur. For the Patristic tradition, the process of dynamic development of creatures is not unknown and it is directly related to the completion of the universe, which is not a moral issue but an ontological and cosmological one

Cosmological particle creation in Weyl geometry

We investigated the possibility of the homogeneous and isotropic cosmological solution in Weyl geometry, which differs from the Riemannian geometry by adding the so called Weyl vector. The Weyl gravity is obtained by constructing the gravitational Lagrangian both to be quadratic in curvatures and conformal invariant. It is found that such solution may exist provided there exists the direct interaction between the Weyl vector and the matter fields. Assuming the matter Lagrangian is that of the perfect fluid, we found how such an interaction can be implemented. Due to the existence of quadratic curvature terms and the direct interaction the perfect fluid particles may be created straight from the vacuum, and we found the expression for the rate of their production which appeared to be conformal invariant. In the case of creating the Universe ‘from nothing’ in the vacuum state, we investigated the problem, whether this vacuum may persist or not. It is shown that the vacuum may persist with respect to producing the non-dust matter (with positive pressure), but cannot resist to producing the dust particles. These particles, being non-interactive, may be considered as the candidates for dark matter.

Thermodynamics of modified gravity theories with matter creation models

Thermodynamics of modified gravity theories with matter creation models