Annals of Physics最新文献

Some time ago, it has been suggested that gravitons can acquire mass in the process of spontaneous symmetry breaking of diffeomorphisms through the condensation of scalar fields [Chamseddine and Mukhanov, JHEP, 2010]. Taking this possibility into account, in the present paper, first we show how the graviton mass intricately reshapes the gravitational potential akin to a Yukawa-like potential at large distances. Notably, this long-range force modifies the Newton’s law in large distances and might explain the phenomena of dark matter. The most important finding in the present paper is the derivation of a modified Newtons law of gravity by modifying the Verlinde’s entropic force relation due to the graviton contribution. The graviton contribution to the entropy basically measures the correlation of graviton and matter fields which then reproduces the Bekenstein–Hawking entropy at the horizon. This result shows the dual description of gravity: in the language of quantum information and entropy the gravity can be viewed as an entropic force, however in terms of particles and fields, it can be viewed as a long range force. Further we have recovered the corrected Einstein field equations as well as the $\Lambda$CDM where dark matter emerges as an apparent effect.

We investigate the dynamics and the phase-space evolution for the scalar nonmetricity cosmology with a Chameleon mechanism. In particular, we consider a spatially flat Friedmann–Lemaître–Robertson–Walker geometry and within the framework of scalar nonmetricity theory, we consider a generalization of the Brans–Dicke theory in nonmetricity gravity. Introducing a pressureless gas as the matter source, we also incorporate a coupling function responsible for the interaction. Our findings reveal that the choice of connection in nonmetricity gravity significantly impacts the interaction between the scalar field and the matter source. For one particular connection, we discover the absence of asymptotic solutions with a nontrivial interacting component. More precisely, in this scenario, the matter source does not directly interact with the scalar field; however, there is an interaction with the dynamical degrees of freedom provided by the connection.

In this paper, we examine the bound state solutions of the $D$-dimensional Klein–Gordon equation for a deformed Deng–Fan potential in generalized form along with Yukawa potential class. The supersymmetric quantum mechanics method and Nikiforov–Uvarov method are employed, utilizing a proper correspondence to the centrifugal potential term. Remarkably, in both methods, we obtain the same analytical expressions for normalized wave functions and energy eigenvalues, expressed in closed form by hypergeometric functions and Jacobi polynomials, for all $l$ and $n$ quantum states. Additionally, we explore the thermodynamic quantities (internal energy, partition function, specific heat, entropy and free energy) in case of both relativistic and non-relativistic regimes for the aforementioned potential. Finally, we demonstrate energy variation against various potential parameters for a few diatomic molecules pictorially.

This study presents novel and physically plausible wormhole solutions within the framework of $f(Q,T)$ gravity theory, incorporating conformal symmetries. The investigation explores the feasibility of traversable wormholes under diverse scenarios, considering traceless, anisotropic, and barotropic equations of state. Additionally, the influence of model parameters on the existence and characteristics of these wormhole structures is thoroughly examined. Notably, the derived shape function satisfies all the necessary criteria. Furthermore, in one of the cases, the presence of non-exotic fluid is confirmed, while in others, exotic matter is only required near the wormhole throat.

The Wu–Yang fiber bundle approach to magnetic charge is extended with a disk-like sheet current density and associated magnetic field in the overlap region between the Northern hemisphere and Southern hemisphere, where the different vector potentials connect. This disk magnetic field plays a role similar to the Dirac string in the Dirac approach to magnetic charge — it brings an inward magnetic flux of $4\pi g$ which then gives rise to an outward Coulomb magnetic flux of $4\pi g$. As with the Dirac string approach we show that placing an electric charge near this disk magnetic field gives rise to a non-zero electromagnetic field momentum. We discuss some of the possible physical consequences of this electromagnetic field momentum. We conclude by showing that the non-singular, but non-single valued Banderet monopole potential also has a disk-like magnetic flux and non-zero electromagnetic field momentum in the presence of an electric charge.

We propose a protocol based on a tunneling plus particle-detection process aimed at generating tripartite entanglement in a system of 3 indistinguishable fermions in a triple-well potential, initially prepared in a state exhibiting only exchange correlations. Particular attention is paid to the generation of fermionic ghz- and w-type states, which are analogous to the usual ghz- and w-type states defined in composites of distinguishable qubits. The protocol succeeds in generating fermionic w-type states, and the ensuing state becomes effectively equivalent to a 3-distinguishable-qubit w-type state shared among three localized parties. The protocol, however, is unable to generate ghz-type states, a result that highlights the fundamental inequivalence between these two types of states, and throws light into the characterization of processes that guarantee the emergence of specific kinds of multipartite entanglement in systems of identical parties. Our findings suggest new paths for the exploration, generation and exploitation of multipartite entanglement in composites of indistinguishable particles, as a useful resource for quantum information processing.

Ever since Hawking highlighted the puzzle of the existence of a singularity in the classical spacetime of general relativity, implying breakdown of all laws of physics living in the classical spacetime, singularity resolution became a problem of significantly high importance. This undesirable feature, indicating loss of predictability, has intrigued physicists over several decades. It has been hoped that the classical singularity would be resolved in a quantum theory of gravity. However, no appropriate wave function in the vicinity of the black hole singularity has been obtained so far to reach a definite conclusion.

In this paper, we focus upon the interior of the Schwarzschild black hole, plagued by a non-removable classical singularity. We consider the interior spacetime of the black hole to be represented by the Kantowski–Sachs metric. Since in a quantum mechanical scenario, existence of spontaneous fluctuations of matter fields should not be ignored, we include a Klein–Gordon field in the system. Quantizing this simple gravity-matter model in the canonical scheme, we obtain the Wheeler–DeWitt equation and find an exact solution in the minisuperspace variables.

We find that there exist three classes of solutions belonging to three different subregions of the eigenvalue space. Two of these classes of solutions admit the DeWitt criterion, a necessary condition for singularity resolution, implied by vanishing of the wave function at the singularity. These solutions are well-behaved and finite in the vicinity of the singularity and they indicate the existence of regular black holes in quantum gravity. In these classes of solutions, we further find that the expectation value of the Kretschmann operator is well-behaved and regular near the singularity, confirming a definite resolution to the puzzle of classical black hole singularity. On the other hand, there exists a small subregion in the eigenvalue space where the solution does not satisfy both conditions, the DeWitt criterion and finiteness of the Kretschmann expectation value at the singularity. This last class of solutions does not represent regular quantum black holes.

A gauge invariant mathematical formalism based on deformation quantization is outlined to model an $N=2$ supersymmetric system of a spin $1/2$ charged particle placed in a nocommutative plane under the influence of a vertical uniform magnetic field. The noncommutative involutive algebra $(C^{\infty }\left(R^2\right)\left[\left[\vartheta \right]\right],{\ast }^r)$ of formal power series in $\vartheta$ with coefficients in the commutative ring $C^{\infty }\left(R^2\right)$ was employed to construct the relevant observables, viz., SUSY Hamiltonian $H$, supercharge operator $Q$ and its adjoint $Q^{†}$ all belonging to the 2 × 2 matrix algebra $M_2(C^{\infty }\left(R^2\right)\left[\left[\vartheta \right]\right],{\ast }^r)$ with the help of a family of gauge-equivalent star products ${\ast }^r$. The energy eigenvalues of the SUSY Hamiltonian all turned out to be independent of not only the gauge parameter $r$ but also the noncommutativity parameter $\vartheta$. The nontrivial Fermionic ground state was subsequently computed associated with the zero energy which indicates that supersymmetry remains unbroken in all orders of $\vartheta$. The Witten index for the noncommutative SUSY Landau problem turns out to be $-1$ corroborating the fact that there is no broken supersymmetry for the model we are considering.

A method is described for the extrapolation of perturbative expansions in powers of asymptotically small coupling parameters or other variables onto the region of finite variables and even to the variables tending to infinity. The method involves the combination of ideas from renormalization group theory, approximation theory, dynamical theory, and optimal control theory. The extrapolation is realized by means of self-similar factor approximants, whose control parameters can be uniquely defined. The method allows to find the large-variable behavior of sought functions knowing only their small-variable expansions. Convergence and accuracy of the method are illustrated by explicit examples, including the so-called zero-dimensional field theory and anharmonic oscillator. Strong-coupling behavior of Gell-Mann–Low functions in multicomponent field theory, quantum electrodynamics, and quantum chromodynamics is found, being based on their weak-coupling perturbative expansions.

We study the Uhlmann geometric phase of a spin-1 particle subjected to zero-field splitting (ZFS) interaction, modulated by a dimensionless parameter $\alpha$, under the effect of an external magnetic field with a tilting angle $\theta$. We show that the ZFS term induces a transition in the geometrical phase behavior, characterized by a critical parameter value, $\alpha ={\alpha }_c$. For $\alpha <{\alpha }_c$, this phase displays two critical temperatures at $\theta =\pi /2$, similar to spin-1 systems without ZFS, but with a separation that varies with $\alpha$. In contrast, for $\alpha >{\alpha }_c$, the phase exhibits two singularities at a single critical temperature but at different field orientations $\theta \ne \pi /2$. The phase disappears for significantly large $\left|\alpha \right|$, regardless of the values of the Hamiltonian parameters. This behavior clearly departs from the usual thermal Uhlmann phase observed in SU(2) systems. In addition, we analytically calculate the heat capacity, which, for $\theta =\pi /2$ and nearby values, displays two different regimes according to the sign of $\alpha$. For $\alpha <0$, it develops two peaks associated to the multilevel nature of the system, while for $\alpha >0$ only a single Schottky-anomaly like peak appears as in two level systems. Interestingly, when $\theta =\pi /2$, the temperature centroids of the Uhlmann phase and the heat capacity coincide in the region between critical temperatures for a given value of $\alpha <{\alpha }_c$. Furthermore, we demonstrate that when $\alpha =0$, the Uhlmann phase, a global topological property of the system, can be expressed as a function of the thermal component of the Bures metric, a local geometric property related to the heat capacity.