Abstract The reason for the present accelerated expansion of the Universe stands as one
of the most profound questions in the realm of science, with deep connections to
both cosmology and fundamental physics. From a cosmological point of view,
physical models aimed at elucidating the observed expansion can be categorized
into two major classes: dark energy and modified gravity. We
review various major approaches that employ a single scalar field to account for the
accelerating phase of our present Universe.
Dynamical system analysis is employed in several important models to seek for cosmological solutions that exhibit an accelerating phase as an attractor.
For scalar field models of dark energy, we consistently focus on addressing challenges related to the fine-tuning and coincidence problems in cosmology, as well as exploring potential solutions to them. For scalar-tensor theories and their generalizations, we emphasize the importance of constraints on theoretical parameters to ensure overall consistency with experimental tests. 
Models or theories that could potentially explain the Hubble tension are also emphasized throughout this review.

Recently, a dual relation T 0(n + 1) = T HP (n) between the minimum temperature (T 0(n + 1)) black hole phase and the Hawking–Page transition (T HP (n)) black hole phase in two successive dimensions was introduced by Wei et al (2020 Phys. Rev. D 102 10411); this was reminiscent of the anti-de Sitter/conformal field theory (AdS/CFT) correspondence, as the Hawking–Page transition temperature could be treated as the temperature of the dual physical quantity on the boundary and the latter corresponds to that in the bulk. In this paper, we discuss the Hawking–Page transition and the dual relations in AdS black holes surrounded by dark energy in general dimensions. Our findings reveal the occurrence of the Hawking–Page transition between the thermal AdS radiation and thermodynamically stable large AdS black holes, in both the spacetime surrounded by phantom dark energy and the spacetime surrounded by quintessence dark energy. We discuss the effects of the phantom dark energy and quintessence dark energy on the Hawking–Page transition temperature. For the dual relation in particular, it works well for the case of an AdS black holes surrounded by phantom dark energy. For the case of an AdS black hole surrounded by quintessence dark energy, the dual relation should be modified under an open assumption that the state parameter and the density parameter of the quintessence dark energy depend on the dimensions of the spacetime.

Abstract By means of the multilinear variable separation(MLVS) approach, new interaction solutions with low-dimensional arbitrary functions of the (2+1)-dimensional NNV-type system are constructed. Four-dromion structure, ring-parabolic soliton structure and corresponding fusion phenomena for the physical quantity U=ln f_{xy} are revealed for the first time. This MLVS approach can also be used to deal with the (2+1)-dimensional Sasa-Satsuma system.

Abstract We explore the variable generalized Chaplygin gas (VGCG) model in the theory of matter creation cosmology within the framework of a spatially homogeneous and isotropic flat Friedmann - Lema\^{i}tre - Robertson - Walker space-time. Matter creation cosmology is based on reinterpretation of energy-momentum tensor in Einstein's field equations. This creation corresponds to an irreversible energy flow from the gravitational field to the created matter constituents. The variable Chaplygin gas (VCG) is also studied as a particular solution. We use the Markov Chain Monte Carlo method to constrain the free parameters of three models, namely, $\Lambda$CDM, VGCG and VCG models with and without matter creation from the latest observational data from baryon acoustic oscillations, cosmic chronometer, type Ia supernovae (Pantheon) including gamma-ray burst, quasars, and the local measurement of $H_0$ from R21 data. Two different combinations of dataset provide a fairly tight constraint on the parameters of the $\Lambda$CDM, VGCG and VCG models. The present values of various cosmological parameters are obtained which give very close to $\Lambda$CDM model. Furthermore, we perform the stability analysis, Bayesian evidence analysis and information criteria analysis for these models through studying the sound speed, Bayes factor, and AIC and BIC selection criterion. The values of sound speed for VGCG and VCG models shows that both the models are stable. According to AIC, it is observed that VGCG and VCG models with matter creation are supported considerably less by current observations whereas BIC shows that these models are not favoured by observational data.

It is well known that nonlocal coherence reflects nonclassical correlations better than quantum entanglement. Here, we analyze nonlocal coherence harvesting from the quantum vacuum to particle detectors adiabatically interacting with a quantum scalar field in Minkowski spacetime. We find that the harvesting-achievable separation range of nonlocal coherence is larger than that of quantum entanglement. As the energy gap grows sufficiently large, the detectors harvest less quantum coherence, while the detectors could extract more quantum entanglement from the vacuum state. Compared with the linear configuration and the scalene configuration, we should choose the model of equilateral triangle configuration to harvest tripartite coherence from the vacuum. Finally, we find a monogamous relationship, which means that tripartite l1-norm of coherence is essentially bipartite types.

We consider generating maximally entangled states (Bell states) between two qubits coupled to a common bosonic mode, based on f-STIRAP. Utilizing the systematic approach developed by Wang et al (2017 New J. Phys. 19 093016), we quantify the effects of non-adiabatic leakage and system dissipation on the entanglement generation, and optimize the entanglement by balancing non-adiabatic leakage and system dissipation. We find the analytical expressions of the optimal coupling profile, the operation time, and the maximal entanglement. Our findings have broad applications in quantum state engineering, especially in solid-state devices where dissipative effects cannot be neglected.

Abstract The role of the delta isobar degrees of freedom in nucleon-nucleon scattering is revisited. We attempt to understand why the dimensionally regularized two-pion exchanges with the explicit delta isobar is much stronger than the ones with spectral function regularization. When the cutoff value of spectral function regularization is varied, the isoscalar central component exhibits a rather large cutoff variation. This reveals a surprisingly large numerical factor of the deltaful two-pion exchange potentials. The power counting is adjusted accordingly and we discuss the results and how to improve upon this finding.

The Hubble tension persists as a challenge in cosmology. Even early dark energy (EDE) models, initially considered the most promising for alleviating the Hubble tension, fall short of addressing the issue without exacerbating other tensions, such as the S 8 tension. Considering that a negative dark matter (DM) equation of state (EoS) parameter is conducive to reduce the value of the σ 8 parameter, we extend the axion-like EDE model in this paper by replacing the cold dark matter (CDM) with DM characterized by a constant EoS w dm (referred to as WDM hereafter). We then impose constraints on this axion-like EDE extension model, along with three other models: the axion-like EDE model, ΛWDM, and ΛCDM. These constraints are derived from a comprehensive analysis incorporating data from the Planck 2018 cosmic microwave background, baryon acoustic oscillations, and the Pantheon compilation, as well as a prior on H 0 (i.e. H 0 = 73.04 ± 1.04, based on the latest local measurement by Riess et al) and a Gaussianized prior on S 8 (i.e. S 8 = 0.766 ± 0.017, determined through the joint analysis of KID1000+BOSS+2dLenS). We find that although the new model maintains the ability to alleviate the Hubble tension to ∼1.4σ, it still exacerbates the S 8 tension to a level similar to that of the axion-like EDE model.

Abstract One of the most influential physical models for explaining the transmission of an optical soliton in optical fibre theory is the nonlinear Schrödinger equation (NLSE). Due to its many potential uses in communications and ultrafast signal routing systems, chiral soliton propagation in nuclear physics is a subject that holds a great deal of interest. This work employs a number of in-depth analytical techniques to deal with the (1+1)-dimensional chiral NLSE that describes the soliton behaviour in transmission of data and has application in the fields of nuclear physics, optics, ionised science, particle physics, and in other applied disciplines mathematical sciences. With the help of applied strategies, we are able to develop different types of solutions that demonstrate behaviour of singular soliton solution, periodic soliton solution, v-shaped soliton, chiral soliton and bell shaped soliton solutions behaviour. Additionally, we discuss the stability analysis for the established solution of the governing model to validate the scientific computations. For the best understanding of solutions behaviour the 3D, contour, and 2D graphics are included. The strategies used are reliable, simple, and efficient. The obtained solution has applications in various computational physics phenomena as well as in other real-world situations and a wide range of academic disciplines.