Exotic Matter Research Articles

Imprints of Casimir wormhole in Einstein Gauss–Bonnet gravity with non-vanishing complexity factor

This article investigates Casimir wormhole solutions in Einstein Gauss–Bonnet (EGB) gravity. We are familiar that Null energy conditions (NEC) need not be satisfied for a stable wormhole due to the existence of exotic matter. As the Casimir effect acts as a negative energy source, it can be treated as a classical applicant for the exotic matter to discuss the stable dynamics of the wormhole. This work explores the Casimir effects with the Generalized Uncertainty Principle (GUP) on wormhole geometry in EGB gravity by confining our results for D=5. We have examined two GUP procedures, e.g., Kempf, Mangano, Mann (KMM) and Dentournay, Gabriel, and Spindel (DGS). We have developed shape functions for Casimir wormholes, and GUP corrected Casimir wormholes and studied their existence. In addition, we investigate the behavior of the Gauss–Bonnet (GB) Coupled parameter and minimal uncertainty (MU) parameter on the Equation of state (EOS) parameter. The active gravitational mass and embedding diagrams for all developed shape functions are analysed. Moreover, the violation of the NEC by an exotic matter, the equilibrium forces, and the complexity factor of Casimir wormholes and GUP-corrected Casimir wormholes have also been explored.

Wormhole solutions in [formula omitted] gravity

In this work, we intend to explore wormhole geometries in the framework of f(R,Lm) gravity. We derive the field equations for the generic f(R,Lm) function by assuming the static and spherically symmetric Morris–Thorne wormhole metric. Then we consider two non-linear f(R,Lm) model, specifically, f(R,Lm)=R2+Lmα and f(R,Lm)=R2+(1+λR)Lm, where α and λ are free model parameters. We obtain the wormhole solutions by assuming three cases, namely, a linear barotropic EoS, anisotropic EoS, and isotropic EoS corresponding to model I. We observe that for both barotropic and anisotropic cases, the corresponding wormhole solutions obey the flaring-out condition under asymptotic background, while for the isotropic case, the shape function does not follow the flatness condition. Also, we find that the null energy condition exhibits negative behavior in the vicinity of the throat. Further, we consider two different shape functions to investigate the behavior of model II. We find some constraints on the model parameter for which the violation of the null energy condition exhibits. Finally, we employ the volume integral quantifier to calculate the amount of exotic matter required near the wormhole throat for both models. We conclude that the modification of standard GR can efficiently minimize the use of exotic matter and provide stable traversable wormhole solutions.

Development of Bethe–Salpeter theory for dealing with unstable system

In the framework of relativistic quantum field theory, the solution of homogeneous Bethe–Salpeter equation for two-body bound state can not describe unstable system, so we develop Bethe–Salpeter theory to investigate resonance which is regarded as an unstable two-body system. Based on Bethe–Salpeter wave function, we consider the time evolution of two-body bound state determined by the total Hamiltonian. The total matrix element for arbitrary decay channel is expressed in terms of the Heisenberg picture, and Mandelstam’s approach is generalized to calculate the matrix element between bound states with respect to arbitrary value of the final state energy. Some innovations to Feynman diagram are made so that the key features of dispersion relation can be more clearly exhibited. This new resonance theory in quantum field theory is applied to investigate exotic particle which is considered as an unstable meson–meson molecular state.

On possible wormhole solutions supported by non-commutative geometry within [formula omitted] gravity

Non-commutativity is a key feature of spacetime geometry. The current article explores the traversable wormhole solutions in the framework of f(R,ℒm) gravity within non-commutative geometry. By using the Gaussian and Lorentzian distributions, we construct tideless wormholes for the nonlinear f(R,ℒm) model f(R,ℒm)=R2+ℒmα. For both cases, we derive shape functions and discuss the required different properties with satisfying behavior. For the required wormhole properties, we develop some new constraints. The influence of the involved model parameter on energy conditions is analyzed graphically which provides a discussion about the nature of exotic matter. Further, we check the physical behavior regarding the stability of wormhole solutions through the TOV equation. An interesting feature regarding the stability of the obtained solutions via the speed of sound parameters within the scope of average pressure is discussed. Finally, we conclude our results.

Traversable wormhole models supported by a string cloud in rainbow gravity

The traversable wormholes are fascinating as the shortcuts in space–time. This work discusses the geometry of a traversable wormhole with a string cloud as a source in rainbow gravity. The field equations are developed and solved to obtain the wormhole’s shape function, cloud’s mass density, and string tension. We have calculated the shape function and made it specific to study the dynamics for toy model. Based on the three well-known pairs of rainbow functions (mentioned by Ali and Khalil), the string cloud’s dynamical variables including mass density and string tension are graphically presented. The corresponding energy conditions are also visually depicted. It is found that the source matter (string cloud) of the traversable wormhole must be exotic. However, the positive values of the string tension led to the presence of Casimir and dark energy effects. It is found that the toy model respects the null energy condition for a single pair of rainbow functions, i.e., Rainbow Function Type II. We have concluded that in rainbow gravity theory, the traversable wormhole solutions originating from a string cloud requires the presence of exotic matter to achieve a stable structure.

Traversable thin-shell wormhole in the 4D Einstein–Gauss–Bonnet theory

This work investigates the spherically symmetric thin-shell wormhole solutions in four-dimensional Einstein–Gauss–Bonnet theory and explores their stabilities under radial, linear perturbations. These solutions are typically traversable and characterized by a thin-shell throat in accordance with Israel’s junction conditions. In asymptotically flat and AdS spacetimes with a negative Gauss–Bonnet coupling constant, stable neutral wormholes are encountered when the magnitude of the coupling constant becomes significant. The throats of such wormholes are sustained by ordinary matter and possess finite radii. In asymptotically dS spacetimes, no stable neutral wormhole featuring ordinary matter is observed. On the other hand, for positive Gauss–Bonnet coupling constant, stable thin-shell wormhole solutions can be established when the throats are exclusively supported by exotic matter. Moreover, stable charged wormholes comprised of ordinary matter are found universally in the asymptotically flat, AdS, and dS spacetimes. Unlike their neutral counterparts, the throat radii of such charged wormholes can be arbitrarily small. However, as the charge becomes more significant, such solutions only remain stable when supported by exotic matter.

Quark matter supported wormhole in third order Lovelock gravity

It is generally believed that wormholes are supported by exotic matter violating Null Energy Condition (NEC). However, various studies of wormhole geometries under Lovelock theories of gravity have reported existence of wormhole supported by matter satisfying NEC. Being inspired by these results, we explore the possibility of the existence of wormhole supported by normal quark matter in third order Lovelock gravity theory. Well known MIT Bag Model Equation of state is chosen for describing the quark matter. Taking physically acceptable approximations, we solve the field equations for shape function which satisfies flare out condition. The residual of the approximate solution is studied for accuracy and found to be acceptable.

Frequencies of f - and p -oscillation modes in cold and hot compact stars

A large collection of equations of state (EOSs) built within the covariant density functional theory of hadronic matter and allowing for density dependent couplings is employed to study polar $f$- and $p$-oscillations of cold and hot compact stars. Correlations between oscillation frequencies of cold purely nucleonic neutron stars (NSs), their global parameters as well as properties of nuclear matter (NM) are investigated by considering a set of models from Beznogov and Raduta, [Phys. Rev. C 107, 045803 (2023)], where a number of constraints on the saturation properties of NM, pure neutron matter and the lower bound of the maximal NS mass were imposed within a Bayesian framework. The roles of finite temperature and exotic particle degrees of freedom, e.g., hyperons, $\mathrm{\ensuremath{\Delta}}$-resonances, antikaon condensates or a hadron to quark phase transition, are addressed by employing a family of models publicly available on compose and assuming idealized profiles of temperature or entropy per baryon and charge fraction. We find that finite temperature effects reduce the oscillation frequencies of nucleonic stars while the opposite effect is obtained for stars with exotic particle degrees of freedom. When the $\mathrm{\ensuremath{\Gamma}}$-law is employed to build finite temperature EOSs, errors in estimating oscillation modes frequencies are of the order of 10% to 30%, depending on the mass. Throughout this work the Cowling approximation is used.

Decays of a bino-like particle in the low-mass regime

We study the phenomenology associated with a light bino-like neutralino with mass \lsim m_{\tau}≲mτ in the context of the R-parity violating Minimal Supersymmetric Standard Model. This is a well-motivated example of scenarios producing potentially light and long-lived exotic particles, which might be testable in far-detector experiments, such as the FASER experiment at the Large Hadron Collider. A quantitative assessment of the discovery potential or the extraction of limits run through a detailed understanding of the interactions of the light exotic fermion with Standard Model matter, in particular, the hadronic sector. Here, we propose a systematic analysis of the decays of such a particle and proceed to a model-independent derivation of the low-energy effects, so that this formalism may be transposed to other UV-completions or even stand as an independent effective field theory. We then stress the diversity of the possible phenomenology and more specifically discuss the features associated with the R-parity violating supersymmetric framework, for example neutron-antineutron oscillations.

Search for long-lived particles decaying to a pair of muons in proton-proton collisions at sqrt{s} = 13 TeV

An inclusive search for long-lived exotic particles decaying to a pair of muons is presented. The search uses data collected by the CMS experiment at the CERN LHC in proton-proton collisions at sqrt{s} = 13 TeV in 2016 and 2018 and corresponding to an integrated luminosity of 97.6 fb−1. The experimental signature is a pair of oppositely charged muons originating from a common secondary vertex spatially separated from the pp interaction point by distances ranging from several hundred μm to several meters. The results are interpreted in the frameworks of the hidden Abelian Higgs model, in which the Higgs boson decays to a pair of long-lived dark photons ZD, and of a simplified model, in which long-lived particles are produced in decays of an exotic heavy neutral scalar boson. For the hidden Abelian Higgs model with m(ZD) greater than 20 GeV and less than half the mass of the Higgs boson, they provide the best limits to date on the branching fraction of the Higgs boson to dark photons for cτ(ZD) (varying with m(ZD)) between 0.03 and ≈0.5 mm, and above ≈0.5 m. Our results also yield the best constraints on long-lived particles with masses larger than 10 GeV produced in decays of an exotic scalar boson heavier than the Higgs boson and decaying to a pair of muons.

Thin-shell wormholes in N-dimensional F(R) gravity

In this work, spherically symmetric thin-shell wormholes with a conformally invariant Maxwell field for [Formula: see text]-dimensional [Formula: see text] gravity and constant scalar curvature [Formula: see text] are built. Two cases are considered: wormholes symmetric across the throat and asymmetric ones having different values of the scalar curvature across the throat. Their stability under radial perturbations is analyzed, finding that unstable and stable solutions are possible for suitable values of the parameters, always made of exotic matter. The stable solutions are found for a short range, slightly over a large critical value of charge.

Geometric structures of Morris-Thorne wormhole metric in f(, ℒ m ) gravity and energy conditions

The aim of this manuscript is to study the traversable wormhole (WH) geometries in the curvature matter coupling gravity. We investigate static spherically symmetric Morris-Thorne WHs within the context of gravity. To accomplish this, we examine the WH model in four different cases (i) linear model, with anisotropic matter distribution having the relation p r = mp t (ii) linear model having anisotropic matter distribution along with the equation of state parameter, p r = ω ρ, (iii) non-linear model with specific form of energy density and (iv) non-linear model, with isotropic matter distribution and having the linear relation between pressure and energy density, p = ω ρ. Additionally, in the latter case, we consider a specific power-law shape function . Furthermore, we analyze the energy conditions for each WH model to verify their physical viability. As a novel outcome, we can see the validation of the null energy condition for the model that suggests ruling out the necessity of exotic matter for the traversability of the WH. At last, an embedding diagram for each model is illustrated that describes the WH geometry.

New classes of wormhole model in [formula omitted] gravity by assuming conformal motion

The two models of wormhole in f(R,T) gravity using relationship between radial and transverse pressure is discussed in the article. To obtain the wormhole model, we used a separable functional form given by f(R,T)=f1(R)+f2(T). R is the Ricci scalar, and T is the trace of the energy momentum tensor, with f1(R) and f2(T) being arbitrary functions of R and T, respectively. We also explored the possibility of wormhole (WH) solutions by assuming that the spacetime admits conformal killing vectors. Using different values for the coupling parameter γ, we studied the viable solutions and graphically analyzed the various features of these models. It can also be noted that the energy conditions are violated for our anisotropic model and isotropic model violates null energy condition (NEC) for γ = 0,−2,−4 while holds NEC for γ = 2,4. Hence, the anisotropic WH throat is supported by exotic matter and the isotropic by exotic/non-exotic (i.e. γ = 0,−2,−4 & γ = 2,4) although not an interesting model as there is no opening throat.

Cosmic bounce and phantom-like equation of state from tunnelling

We allow a scalar field on a flat FLRW background metric to tunnel between two degenerate vacua. The resulting true vacuum state then violates the Null Energy Condition, and the corresponding homogeneous fluid induces a bounce, after which it has a phantom-like equation of state and asymptotically leads to a de Sitter phase. The mechanism presented here requires no exotic matter or modified gravity, it is purely generated by quantum fluctuations and is valid for a generic double well potential.

Magnetic‐Field Regulation of Nodal Topological Superconducting States in Monolayer Ising Superconductor NbSe2

The nodal topological superconducting (NTSC) state with Majorana flat bands (MFBs) is an exotic matter of state hosting Majorana fermions that obey non‐Abelian statistics. Recently, monolayer Ising superconductor NbSe2 is shown to be an ideal platform for realizing an NTSC state. Through tight‐binding calculations based on the Bogoliubov–de–Gennes Hamiltonian, it is demonstrated that the in‐plane magnetic field B combined with superconducting pairing Δs, Rashba spin–orbit coupling (SOC) Vr, and chemical potential μ can regulate the topological properties of the NTSC state. First, B larger than Δs effectively induces an NTSC state with nodal points (NPs) located on the high‐symmetry line of the Brillouin zone. The length of the resulting MFBs in the ribbon increases with B. Second, Rashba SOC greatly affects the number and locations of NPs by tilting bands near Fermi level (EF), leading to unidirectional Majorana edge states. Finally, when B > Δs, μ affects the bulk band structure at EF, resulting in an NTSC state with 6, 12, 18, 24 NPs and 0, 2, 3, 4 MFBs. These results are important to clarifying the behavior of the NTSC state under a B and designing a quantum computing platform based on exotic Majorana fermions.

Complexity factor parameterization for traversable wormholes

It is known that static traversable wormholes in Einstein gravity are supported by matter that violates null energy conditions (NEC). Essentially, such wormholes will be characterized by a central throat with anisotropic matter lining the throat that violates NEC. This, in turn, provides viable geometry for the wormhole to sustain. In 2018, Herrera [Phys. Rev. D 97, 044010 (2018)] introduced a new classification for spherically symmetric bodies called “complexity factor.” It was proposed that a spherically symmetric non-trivial geometry can be classified as complex or non-complex based on the nature of the inhomogeneity and anisotropy of the stress–energy tensors with only homogeneous and isotropic matter distribution leading to null complexity. Mathematically, there was also another way of obtaining zero complexity geometry. In this context, since static traversable wormholes, by default, are characterized by anisotropic and inhomogeneous matter stress tensors, the question we answer is whether it is possible to obtain zero complexity class of wormholes supported by exotic matter.

경극과 판소리 화용도의 사설 비교 연구

This study compared and analyzed saseol (texts like lyrics and dialogues) of Chinese Peking opera Hwayongdo (華容道 The Huarong Path) and the passage of 'Hwayongdo' in Korean pansori (musical storytelling) Jeokbyeokga. To this end, reviewing the written materials related to the Peking opera Hwayongdo, it found that it was first included under the title Dangcao in Chewangfu quben, a collection of librettos of early Peking opera works from the mid-Qing Dynasty (1636-1912).
 The title Hwayongdo was first used in the 'Qingshengping ban ximu' (repertoire of plays by the Qingshengping troupe) of the Chinese literature Dao Xian yilai Liyuan xinian xiaolu (a small record of the theater from the Daoguang and Xianfeng) at the 4th year of the Daoguang Emperor (1824).
 The results of comparing the saseol of the Peking opera Hwayongdo included in Jingju chuantong juben huibian (a collection of traditional Peking opera scripts) with that of 'Hwayongdo' in Jeokbyeokga performed by Song Sun-seop are as follows. First, the Hwayongdo of the two countries were different in terms of saseol composition by each section. Scenes were added to the beginning section in Peking opera whereas they were added in the middle and final sections in pansori. Second, the development of saseol contents was generally similar, but there were differences in the focal point of the description. Pansori 'Hwayongdo' had a strong tendency to express the character's way of speaking, expression, and appearance vividly and realistically. However, the Peking opera Hwayongdo was concisely organized around the plot.
 This phenomenon is not only because Chinese audiences are more familiar with the contents of the novel The Romance of the Three Kingdoms , but also because the dialogue, acting, and makeup of Peking opera actors were able to vividly express Hwayongdo and thus a realistic description was unnecessary. On the other hand, Korean audiences would have been very curious about the exotic subject matter and characters appearing in 'Hwayongdo' and to satisfy this curiosity, a more detailed description and added content would have been needed.
 This study are significant in that they confirm how the traditional performing art of China and Korea, both based on the same novel The Romance of the Three Kingdoms , has developed as different types of contents in the process of accommodating the performance environment and the taste of audiences.

Embedding procedure and wormhole solutions in Rastall gravity utilizing the class I approach

This paper investigates the wormhole solutions in Rastall theory of gravity using the Karmarkar conditions. For this purpose, we choose a shape function (SF) that connects two asymptotically flat regions. We also discuss the wormhole configuration by plotting three-dimensional (3D) analysis of the embedding diagram in Euclidean space. Furthermore, we also observe the detailed graphical representation of energy conditions using the considered SF. The violation of energy conditions, especially null energy conditions (NEC), indicates the existence of exotic matter and wormholes. Hence, it can be concluded that our calculated results in the background of Rastall theory of gravity are viable and stable. The exciting feature of this work is the 3D analysis to discuss the viability of wormhole geometry

Multipole decomposition of tensor interactions of fermionic probes with composite particles and BSM signatures in nuclear reactions

A multipole decomposition of a cross section is a useful tool to simplify the analysis of reactions due to their symmetry properties. By using a new approach to decompose antisymmetric tensor-type interactions within the multipole analysis, we introduce a general mathematical formalism for working with tensor couplings. This allows us to present a general tensor nuclear response, which is particularly useful for ongoing $\ensuremath{\beta}$-decay experiments looking for physics beyond the Standard Model (BSM), as well as other exotic particle scatterings off nuclei, e.g., in dark matter direct detection experiments. Using this method, BSM operators identify with the known Standard Model operators, eliminating the need for calculations of additional matrix elements. We present in detail BSM expressions useful for $\ensuremath{\beta}$-decay experiments and give an exemplary application for $^{6}\mathrm{He}$ $\ensuremath{\beta}$-decay, although the formalism is easily generalizable for calculating other exotic scattering reactions.

Traversable wormholes with electric charge and scalar field in f(R,T) gravity

Kim and Lee [Phys. Rev. D 63 (2001) 064014] studied charged wormholes and Morris–Thorne wormholes in the presence of scalar field using the concepts of general relativity. In this paper, we have also considered same wormholes affected with electric charge and scalar field and extended their study using the framework of [Formula: see text] gravity with [Formula: see text] gravity model, where [Formula: see text] and [Formula: see text] are constants. We have examined the possibility for minimization of the amount of exotic matter through energy conditions. Further, we have obtained the deflection angle, an important notion in gravitational lensing, by using strong field limit coefficients which may be helpful in the detection of wormholes.