Modern Physics Letters A

Advised by Prof. Chen Ning Yang, we review the early pioneering work by Chien-Shiung Wu on entangled photons created from the electron–positron annihilation. This paper formed a basis of the author’s speech at International Symposium Commemorating 110th Birth Anniversary of Chien-Shiung Wu, May 31, 2022, and of a few articles on the subject in Chinese.

In the framework of the singly charged scalar singlet model, we study the possibility of detecting the singly charged $\mathrm{\text{SU}}{(2)}_L$ singlet scalar S through the Drell–Yan process at the High-Luminosity-Large Hadron Collider (HL-LHC) with the center-of-mass energy $\sqrt{s}=14\mathrm{\text{TeV}}$ and the integrated luminosity $\mathcal{ℒ}=3{\mathrm{\text{ab}}}^{-1}$, the High-Energy-Large Hadron Collider (HE-LHC) with $\sqrt{s}=27\mathrm{\text{TeV}}$ and $\mathcal{ℒ}=10{\mathrm{\text{ab}}}^{-1}$ as well as the Future Circular Collider — hadron–hadron (FCC-hh) with $\sqrt{s}=100\mathrm{\text{TeV}}$ and $\mathcal{ℒ}=20{\mathrm{\text{ab}}}^{-1}$. Considering the constraints on the free parameters, after performing a detector level simulation for the signals and relevant backgrounds, we find that the scalar S might be detected in a certain range of the parameter space, which is not excluded by the current constraints.

In our study, we delved into the profound ramifications of string tension on the collapse of a string fluid, culminating in the formation of a black hole within the realm of $f(R)$ gravity. A string fluid is a perfect fluid model, each whose particle admits a radially stretched string. The outer region for the collapsing object is assumed to be the Schwarzschild spacetime, while the fluid collapses in the internal region are supposed to be Friedman–Robertson–Walker spacetime. The junction conditions are developed leading to gravitational mass and energy. The time frame for apparent horizon and singularity formation was estimated, showing a black hole as the outcome. String tension emerged as a pivotal factor in prolonging horizon creation. Our findings illuminate the relation among $f(R)$ gravity, string tension, and collapse dynamics, enriching our understanding of cosmic phenomena.

In this study, we explore white holes using noncommutative Painlevé–Gullstrand (PG) coordinates, integrating noncommutative geometry within the framework of general relativity to describe white holes and eliminate metric singularities at the event horizon. We derive modified Wheeler–DeWitt (WdW) equations and perturbative solutions to address noncommutative effects, finding that these reduce the event horizon radius, decrease entropy, and increase temperature compared to classical Schwarzschild black holes. Additionally, we analyze the probability of quantum tunneling transitions between black holes and white holes, demonstrating that noncommutativity increases this probability, especially for higher mass black holes. The dynamics of massive and massless particles in the vicinity of these noncommutative objects are also explored, revealing significant alterations in effective potential and stability of particle trajectories due to noncommutative effects. This theoretical framework offers novel insights into high-energy physics by bridging general relativity with quantum mechanics through the lens of noncommutative geometry.

In this paper, we implement the Einsenhart–Duval lift in scalar–tensor gravity as a means to construct integrable cosmological models and analytic cosmological solutions. Specifically, we employ a geometric criterion to constrain the free functions of the scalar–tensor theory such that the field equations can be written in the equivalent form of linear equations. This geometric linearization is achieved by the introduction of an extended minisuperspace description. The results are applied to construct analytic solutions in modified theories of gravity such as the $f(R)$-theory and the hybrid metric-Palatini $f({ℛ})$-gravity.

We investigate the time evolutions of purity, coherence and entanglement in two superconducting qubits coupled through Josephson junctions. The system is modeled by coupling strength, energy, Josephson energy and phase difference. Meanwhile, the structure is under the action of thermal field and classical Ornstein–Uhlenbeck (OU) noise. According to our findings, quantum correlations are notably developed governed by the system parameters. Purity and entanglement generally increase for the energetic qubit regimes. The state’s entanglement and purity degrade with increased coupling strength and temperature. On the other hand, the optimal preservation of quantum correlations reqires the adjustment to intermediate Josephson energies ($E_j=0.5$) and phase differences ($\varphi =\pi ∕4$). The coherence measurement shows completely opposite traits compared to the entanglement and purity in the system. These results reveal that quantum states need proper parametrization for the considered state while providing optimization for the higher performance of superconducting qubits in quantum information processing.

In this paper, we present a comprehensive examination of the Lie symmetry analysis, optimal system, exact solutions, and conservation laws pertaining to the variable-coefficient higher-order Boussinesq–Burgers system. The Lie symmetry analysis method is initially employed to derive the vector field, followed by the utilization of Olver’s method to determine the optimal system of one-dimensional subalgebras for the system. By utilizing the optimal system, the Boussinesq–Burgers system is similarly reduced. Subsequently, the $(\frac{G^{\prime }}{G})$-expansion method is applied to this reduced system, yielding kink soliton solution, dark soliton solution, trigonometric-function solution and rational solution for the variable-coefficient higher-order Boussinesq–Burgers system. By assigning various functions to the coefficient functions, different types of soliton solutions are obtained, and these solutions’ structural features are visualized through the use of three-dimensional figures. Last, an examination of the conservation laws governing the system is conducted.

In contemporary optical communications and information processing, solitons are of great interest due to their stability in nonlinear media. Spatiotemporal solitons are optical wave packets with localized structures in both time and space that demonstrate efficient transmission in multimode fibers. This study focuses on the generation and dynamics of spatiotemporal optical soliton molecules in graded-index multimode fibers. The bilinear Hirota’s method is utilized to solve the Gross–Pitaevskii (GP) equations governing the evolution of these solitons. By applying these solutions, the complex dynamical behavior of soliton molecules is investigated as it is influenced by variations in specific parameters. Additionally, this research analyzes the interactions among spatiotemporal soliton molecules in multimode fibers under different binding states through parametric manipulation. The findings provide novel insights into nonlinear optical phenomena in graded-index multimode optical fibers.

Tensor-scalar theories of gravitation are commonly employed as extensions of General Relativity that allow to describe a much wider phenomenology. They are also naturally generated as low energy limits of higher-dimensional or unified theories, and the gravitational scalar components can represent quantum corrections to the Einstein theory. The coupling of the scalars to an e.m. field does not introduce any relevant new physics if the e.m. action has the usual Maxwell form, implying a vanishing trace of the e.m. energy–momentum tensor. In the case of the extended Aharonov–Bohm electrodynamics, some interesting new situations are possible, which in this work are analyzed in the gravitational weak-field approximation and for a basic version of tensor-scalar gravity involving only a Brans–Dicke field plus another scalar. Since Aharonov–Bohm theory differs from Maxwell theory only in the presence of anomalous sources with local violation of charge conservation, which is thought to be possible only at a quantum level, the resulting formal framework can be useful for modeling interactions between gravitational and physical systems with macroscopic quantization. The theory contains some unknown parameters, the most important being the vacuum expectation value (VEV) ${\psi }_0$ of the second gravitational scalar and the level $\gamma$ of violation of local charge conservation in the e.m. sector. An attempt is made to relate these parameters to some experimental constraints. However, presently there is much space left for uncertainty.

The Amaterasu cosmic ray particle announced in November 2023 is extraordinary. Its direction points back to the Local Void which contains no galaxies or known source. It is possible to show that the direction could not have been bent significantly by magnetic fields within the Milky Way. This collection of facts constitutes a paradox. In this paper, we offer a resolution within the Electromagnetic Accelerating Universe (EAU) model in which a central rôle is played by charged Primordial Extremely Massive Black Holes (PEMBHs) whose Coulomb interactions underly accelerating expansion. Because structure formation of PEMBHs is electromagnetic while that for galaxies is gravitational, it is reasonable to expect PEMBHs inside the Local Void. We provide an example where the cosmic ray primary is an antiproton and present it as supporting evidence for the EAU model.