White dwarfs, one of the compact objects in the Universe, play a crucial role in astrophysical research and provide a platform for exploring nuclear physics. In this work, we extend the relativistic mean field approach by using a Walecka-type quantum hadrodynamics model to capture the intricate structure of white dwarfs. We calculate nuclear properties, Coulomb energy, and photon energy within white dwarfs in a unified framework. By carefully calibrating the model parameters to align with nuclear matter properties, we successfully reproduce the structures of several elements in white dwarfs, such as the isotopes of C and ¹⁶O, except for the unnaturally deeply bound state ⁴He. Furthermore, we predict the characteristics of white dwarfs composed of atom-like units and the gravitational waves stemming from binary white dwarf inspirals incorporating tidal deformability contributions up to the 2.5 post-Newtonian order. These results shed light on the structure of white dwarfs and provide valuable information for future gravitational wave detection. This methodological advancement allows for a cohesive analysis of white dwarfs, neutron stars, and the nuclear pasta within a unified theoretical framework.

In the framework of general relativity (GR), gravitational waves (GWs) travel at the speed of light across all frequencies. However, massive gravity and weak equivalence principle (WEP) violation may lead to frequency-dependent variations in the propagation speed of GWs, which can be examined by comparing the theoretical and observed discrepancies in the arrival times of GW signals at various frequencies. This provides us with an opportunity to test these theories. For massive gravity, we consider that gravitons may have a nonzero rest mass. For WEP violations, we hypothesize that different massless particles exposed to the same gravitational source should exhibit varying gravitational time delays. The gravitational time delay induced by massive gravitational sources is proportional to γ + 1, where the parameter γ = 1 in GR. Therefore, we can quantify these two deviations using phenomenological parameters m_g and ∣Δγ∣, respectively. In this study, we use selected GW data from binary black hole coalescences in the LIGO-Virgo catalogs GWTC-2.1 and GWTC-3 to place constraints on the parameters m_g and ∣Δγ∣. We also compute Bayes factors for models that assume the existence of graviton mass and WEP violation compared to the standard GW model, respectively. The absolute value of the natural logarithm of the Bayes factor is generally less than two. Our analysis reveals no significant preference for either model. Additionally, the Bayes factors between these two models do not provide obvious evidence in favor of either one.

We argue that the hypothesis that positive-parity charm meson resonances exhibit a compact tetraquark structure has some clear tension with recent lattice results for the S-wave πD system for an SU(3) flavor symmetric setting. In particular, we show that such a diquark–anti-diquark tetraquark scenario would call for the presence of a state in the flavor $[\overline{{\bf{15}}}]$ representation, not seen in the lattice analysis. Moreover, we show that analogous lattice data in the axial-vector channel are even more sensitive to the internal structure of these very interesting states.

This is a writeup of lectures delivered at the Asian Pacific Introductory School on Superstring and Related Topics in Beijing (2006) and an expanded version of these lectures given at the Third Summer School on Strings, Fields and Holography in Nanjing (2023). It aims to provide both a historical and pedagogical account of developments in finding 1/2 Bogomol'nyi-Prasad-Sommerfield (BPS) extended string solitons during the early stage of the so-called second string revolution, before which these objects were thought to be unrelated to strings. Non-supersymmetric solutions related to brane/anti brane systems or non-BPS systems are also discussed.

The Josephson junction is typically tuned by a magnetic field or electrostatic gate to realize a superconducting (SC) transistor, which manipulates the supercurrent in integrated SC circuits. Here, we propose a theoretical scheme for a light-controlled SC transistor, which is composed of two superconductor leads weakly linked by a coherent light-driven quantum dot. We discover a Josephson-like relation for the supercurrent ${I}_{{\rm{s}}}={I}_{c}({\rm{\Phi }})\,\sin {\rm{\Phi }}$, where both the supercurrent phase Φ and magnitude I_c can be completely controlled by the phase, intensity, and detuning of the driving light. Additionally, the supercurrent magnitude displays a Fano profile with the increase of the driving light intensity, which is understood by comparing the level splitting of the quantum dot under light driving with the SC gap. Moreover, when two such SC transistors form a loop, they constitute a light-controlled SC quantum interference device (SQUID). Such a light-controlled SQUID can demonstrate the Josephson diode effect, and the optimized non-reciprocal efficiency achieves up to 54%, surpassing the maximum record reported in recent literature. Thus, our scheme delivers a promising platform for performing diverse and flexible manipulations in SC circuits.

The theoretical challenges in understanding the nature of glass and glass transition raise significant questions in statistical and condensed matter physics. As a prototypical example of complex physical systems, glasses and the vitrification process have been central research topics, consistently attracting broad scientific interest. This focus has driven extensive studies on phenomena such as aging, non-exponential relaxation, dynamic anomalies, glass-forming ability, and the mechanical response of glasses under stress. Recent advances in computational and experimental techniques have enabled rigorous testing of theoretical models, shedding new light on glass behavior. However, the intrinsic complexity of glass and the glass transition that lies in their physics, which spans multiple length and time scales, makes the system challenging to characterize. In this review, we emphasize the need to move beyond conventional approaches and propose a topological perspective as a promising alternative to address these challenges. Specifically, our findings reveal that the diversity in particle relaxation behavior is statistically linked to a global topological feature of the transient network structures formed by the particles in a given liquid. This direction offers opportunities to uncover novel phenomena that could fundamentally reshape our understanding of glassy materials.

The transverse-traceless gauge condition is an important concept in the theory of gravitational waves. It is well known that a vacuum is one of the key conditions to guarantee the existence of the transverse-traceless gauge. Although it is thin, the interstellar medium is ubiquitous in the Universe. Therefore, it is important to understand the concept of gravitational waves when matter is presented. Bondi–Metzner–Sachs theory has solved the gauge problem related to gravitational waves. But it does not help with cases when the gravitational wave propagates in matter. This paper discusses possible extensions of the transverse-traceless gauge condition to Minkowski perturbation with matter presented.

In the multilayer film-substrate system, thermal stress concentration and stress mutations cause film buckling, delamination and cracking, leading to device failure. In this paper, we investigated a multilayer film system composed of a substrate and three film layers. The thermal stress distribution inside the structure was calculated by the finite element method, revealing significant thermal stress differences between the layers. This is mainly due to the mismatch of the coefficient of thermal expansion between materials. Different materials respond differently to changes in external temperature, leading to compression between layers. There are obvious thermal stress concentration points at the corners of the base layer and the transition layer, which is due to the sudden change of the shape at the geometric section of the structure, resulting in a sudden increase in local stress. To address this issue, we chamfered the substrate and added an intermediate layer between the substrate and the transition layer to assess whether these modifications could reduce or eliminate the thermal stress concentration points and extend the service life of the multilayer structure. The results indicate that chamfering and adding the intermediate layer effectively reduce stress discontinuities and mitigate thermal stress concentration points, thereby improving interlayer bonding strength.

In this work, we studied the electronic and magnetic properties of the double perovskite Sr₂CrMoO₆ using ab initio calculations with generalized gradient approximation (GGA) and Monte Carlo (MC) simulations. The compound has two magnetic sublattices: one occupied by Mo⁵⁺ with spin ($S=\tfrac{1}{2}$) and the other by Cr³⁺ with spin ($\sigma =\tfrac{3}{2}$). The results showed half-metallic behavior with a total magnetic moment of 2.0 μ_B. Using Monte Carlo simulations, we investigated the phase transitions and observed interesting phenomena such as a critical endpoint and both second-order and first-order phase transitions. Additionally, the results revealed compensation points for specific values of the crystal field.

The eikonal approximation (EA) is widely used in various high-energy scattering problems. In this work we generalize this approximation from the scattering problems with time-independent Hamiltonian to the ones with periodical Hamiltonians, i.e., the Floquet scattering problems. We further illustrate the applicability of our generalized EA via the scattering problem with respect to a shaking spherical square-well potential, by comparing the results given by this approximation and the exact ones. The generalized EA we developed is helpful for the research of manipulation of high-energy scattering processes with external field, e.g. the manipulation of atom, molecule or nuclear collisions or reactions via strong laser fields.

We revisit the construction of the ${ \mathcal N }=1$ supersymmetric trinification models with gauge group U(3)_C × U(3)_L × U(3)_R in Type IIA string theory on ${{\mathbb{T}}}^{6}/({{\mathbb{Z}}}_{2}\times {{\mathbb{Z}}}_{2})$ orientifold with intersecting D6-branes. The non-trivial K-theory conditions and tadpole cancellation conditions severely restrict the number of allowed models even for the case of rectangular two-tori. Using a supervised search algorithm, we find a few four-family models where the highest wrapping number is 2. For these models, we present the complete particle spectra and the gauge coupling relations at the string-scale.

This paper aims to propose a fourth-order matrix spectral problem involving four potentials and generate an associated Liouville integrable hierarchy via the zero curvature formulation. A bi-Hamiltonian formulation is furnished by applying the trace identity and a recursion operator is explicitly worked out, which exhibits the Liouville integrability of each model in the resulting hierarchy. Two specific examples, consisting of novel generalized combined nonlinear Schrödinger equations and modified Korteweg–de Vries equations, are given.

This study introduces an innovative dual-tunable absorption film with the capability to switch between ultra-wideband and narrowband absorption. By manipulating the temperature, the film can achieve multi-band absorption within the 30–45 THz range or ultra-wideband absorption spanning 30–130 THz, with an absorption rate exceeding 0.9. Furthermore, the structural parameters of the absorption film are optimized using the particle swarm optimization (PSO) algorithm to ensure the optimal absorption response. The absorption response of the film is primarily attributed to the coupling of guided-mode resonance and local surface plasmon resonance effects. The film's symmetric structure enables polarization incoherence and allows for tuning through various means such as doping/voltage, temperature and structural parameters. In the case of a multi-band absorption response, the film exhibits good sensitivity to refractive index changes in multiple absorption modes. Additionally, the absorption spectrum of the film remains effective even at large incidence angles, making it highly promising for applications in fields such as biosensing and infrared stealth.

 Supermassive black holes (SMBHs) are ubiquitous in the center of galaxies, although the origin of their massive seeds is still unknown. In this paper, we investigate the formation of SMBHs from the quantum chromodynamics (QCD) axion bubbles. In this case, primordial black holes (PBHs) are considered as the seeds of SMBHs, which are generated from the QCD axion bubbles due to an explicit Peccei–Quinn (PQ) symmetry breaking after inflation. The QCD axion bubbles are formed when the QCD axion starts to oscillate during the QCD phase transition. We consider a general case in which the axion bubbles are formed with the bubble effective angle θ_eff ∈ (0, π], leading to the minimum PBH mass $\sim { \mathcal O }({10}^{4}-{10}^{7}){M}_{\odot }$ for the axion decay constant ${f}_{a}\sim { \mathcal O }({10}^{16})\mathrm{GeV}$. The PBHs at this mass region may account for the seeds of SMBHs.

Flocking and vortical are two typical motion modes in active matter. Although it is known that the two modes can spontaneously switch between each other in a finite-size system, the switching dynamics remain elusive. In this work, by computer simulation of a two-dimensional Vicsek-like system with 1000 particles, we find from the perspective of the classical nucleation theory that the forward and backward switching dynamics are asymmetric: going from flocking to vortical is a one-step nucleation process, while the opposite is a two-step nucleation process, with the system staying in a metastable state before reaching the final flocking state.

The effective liquid drop model (ELDM) is improved by introducing an accurate nuclear charge radius formula and an analytic expression for assaulting frequency. Within the improved effective liquid drop model (IMELDM), the experimental cluster radioactivity half-lives of the trans-lead region are calculated. It is shown that the accuracy of the IMELDM is improved compared with that of the ELDM. At last, the cluster radioactivity half-lives that are experimentally unavailable for the trans-lead nuclei are predicted by the IMELDM. These predictions may be useful for searching for new candidates for cluster radioactivity in future experiments.

As with the laser interferometer gravitational-wave observatory (LIGO), the matched filtering technique will be critical to the data analysis of gravitational wave detection by space-based detectors, including LISA, Taiji and Tianqin. Waveform templates are the basis for such matched filtering techniques. To construct ready-to-use waveform templates, numerical relativity waveforms are a starting point. Therefore, the accuracy issue of numerical relativity waveforms is critically important. There are many investigations regarding this issue with respect to LIGO. But unfortunately there are few results on this issue with respect to space-based detectors. The current paper investigates this problem. Our results indicate that the existing numerical relativity waveforms are as accurate as 99% with respect to space-based detectors, including LISA, Taiji and Tianqin. Such an accuracy level is comparable to that with respect to LIGO.

By numerically solving the time-dependent Schrödinger equation and employing the analytical perturbative model, we investigated the chirp-induced electron vortex in the photoionization of hydrogen atoms by a pair of counter-rotating circularly polarized chirped attosecond extremely ultraviolet pulses. We demonstrated that single-photon ionization of hydrogen atoms generates photoelectron momentum distributions (PMDs) with distinct helical vortex structures either with or without a time delay between two counter-rotating circularly polarized laser pulses. These structures are highly sensitive to both the time delay between the pulses and their chirp parameters. Our analytical model reveals that the splitting of vortex spirals is caused by the sign changing of the chirp-induced frequency-dependent time delay. We showed that to obtain the counterpart of the PMD under a pair of counter-rotating circularly polarized chirped pulses, both chirp parameters and ordering of pulses need to be reversed.

The major goal of this work is to find solutions of Einstein-Maxwell field equations for anisotropic, expansion-free, non-static, spherically distributed matter content. The analytical models that highlight the major benefit of simplicity are shown and this makes it possible to use them as a toy model to illustrate how cavities evolve. Furthermore, the transport equations, quasi-homologous constraints and the junction conditions are also evaluated along with their useful implications. Eventually, the consequences of electric force on this system are summed up in the last section.

We derive the hyperbolic orbit of binary black holes with electric and magnetic charges. In the low-velocity and weak-field regime, by using the Newtonian method, we calculate the total emission rate of energy due to gravitational and electromagnetic radiation from binary black holes with electric and magnetic charges in hyperbolic orbits. Moreover, we develop a formalism to derive the merger rate of binary black holes with electric and magnetic charges from the two-body dynamical capture. We apply the formalism to investigate the effects of the charges on the merger rate for the near-extremal case and find that the effects cannot be ignored.

Using the Monte Carlo method, the compensation temperature and hysteresis loops of a ferrimagnetic mixed spin-3/2 and spin-5/2 Ising-type graphene-like bilayer are investigated induced by different physical parameters such as crystal field, exchange coupling, external magnetic field, and temperature. The variations of magnetization, magnetic susceptibility, specific heat, and internal energy with the change of temperature are discussed. In addition, we also plot the phase diagrams including transition temperature and compensation temperature. Finally, multiple hysteresis loops under certain parameters are given.

In this paper, an active tunable terahertz bandwidth absorber based on single-layer graphene is proposed, which consists of a graphene layer, a photo crystal plate, and a gold substrate. When the Fermi energy (E_f) of graphene is 1.5 eV, the absorber shows high absorption in the range of 3.7 THz–8 THz, and the total absorption rate is 96.8%. By exploring the absorption mechanism of the absorber, the absorber shows excellent physical regulation. The absorber also shows good adjustability by changing the E_f of graphene. This means that the absorber exhibits excellent tunability by adjusting the physical parameters and E_f of the absorber. Meanwhile, the absorber is polarization independent and insensitive to the incident angle. The fine characteristics of the absorber mean that the absorber has superior application value in many fields such as biotechnology and space exploration.

The relativistic transformation rule for temperature is a debated topic for more than 110 years. Several incompatible proposals exist in the literature but a final resolution is still missing. In this work, we reconsider the problem of relativistic transformation rules for a number of thermodynamic parameters including temperature, chemical potential, pressure, entropy and enthalpy densities for a relativistic perfect fluid using relativistic kinetic theory. The analysis is carried out in a fully relativistic covariant manner, and the explicit transformation rules for the above quantities are obtained in both Minkowski and Rindler spacetimes. Our results suggest that the temperature of a moving fluid appears to be colder, supporting the proposal by de Broglie, Einstein, and Planck, in contrast to other proposals. Moreover, in the case of a Rindler fluid, our findings suggest that the total number of particles and the total entropy of a perfect fluid in a box whose bottom is parallel to the Rindler horizon are proportional to the area of the bottom, but are independent of the height of the box, provided the bottom of the box is sufficiently close to the Rindler horizon. The area dependence of the particle number implies that the particles tend to be gathered toward the bottom of the box, and hence implicitly determines the distribution of the chemical potential of the system, whereas the area dependence of the entropy indicates that the entropy is still additive and may have potential applications in explaining the area law of black hole entropy. As a by-product, we also obtain a relativistically refined version of the famous Saha equation which holds in both Minkowski and Rindler spacetimes.

Pronounced changes of nuclear charge radii provide a stringent benchmark on the theoretical models and play a vital role in recognizing various nuclear phenomena. In this work, the systematic evolutions of nuclear charge radii along even Z = 84-120 isotopic chains are first investigated by the recently developed new ansatz under the covariant density functional. The calculated results show that the shell closure effects of nuclear charge radii appear remarkably at the neutron numbers N = 126 and 184. Interestingly, the arch-like shapes of charge radii between these two strong neutron-closed shells are naturally observed. Across the N = 184 shell closure, the abrupt increase in charge radii is still evidently emerged. In addition, the rapid raise of nuclear charge radii from the neutron numbers N = 138 to N = 144 is disclosed clearly in superheavy regions due to the enhanced shape deformation.

In this paper, we develop the teleportation scheme in [Zheng in Phys Rev A 69, 064302, 2004], in the sense that, we work in the strong atom-field coupling regime wherein the rotating wave approximation (RWA) is no longer valid. To achieve the purpose, a scheme consisting of a qubit interacting with a single-mode quantized field is described via the Rabi model (counter rotation terms are taken into account). Our first aim is to teleport an unknown atomic state of a qubit (which interacts with the quantized field in a cavity) to a second qubit (exists in another distant cavity field), beyond the RWA and without the Bell-state measurement method. In the continuation, in a similar way, we teleport an unknown state of a single-mode field too. In fact, it is shown that, in this regime, after applying some particular conditions, containing the interaction time of atom-field in the cavities, adjusting the involved frequencies, as well as the atom-field coupling in the model, if a proper measurement is performed on the state of the first qubit (the related field in the cavity), the unknown states of the qubit (field) can be teleported from the first qubit (cavity field) to the second qubit (cavity field), appropriately. We show that in both considered cases, the teleportation protocol is successfully performed with the maximum possible fidelity, 1, and the acceptable success probability, 0.25.

This work studies the dynamical transmission of chirped optical solitons in a spatially inhomogeneous nonlinear fiber with cubic-quintic-septic nonlinearity, weak nonlocal nonlinearity, self-frequency shift and parity-time (${ \mathcal P }{ \mathcal T }$) symmetry potential. A generalized variable-coefficient nonlinear Schrödinger equation that models the dynamical evolution of solitons has been investigated by the analytical method of similarity transformation and the numerical mixed method of split-step Fourier method and Runge–Kutta method. The analytical self-similar bright and kink solitons, as well as their associated frequency chirps, are derived for the first time. We found that the amplitude of the bright and kink solitons can be controlled by adjusting the imaginary part of the ${ \mathcal P }{ \mathcal T }$-symmetric potential. Moreover, the influence of the initial chirp parameter on the soliton pulse widths is quantitatively analyzed. It is worth emphasizing that we could control the chirp whether it is linear or nonlinear by adjusting optical fiber parameters. The simulation results of bright and kink solitons fit perfectly with the analytical ones, and the stabilities of these soliton solutions against noises are checked by numerical simulation.

It is demonstrated that for the isospin I = 1/2 πN scattering amplitude, T^I=1/2(s, t), $s={\left({m}_{N}^{2}-{m}_{\pi }^{2}\right)}^{2}/{m}_{N}^{2}$ and $s={m}_{N}^{2}+2{m}_{\pi }^{2}$ are two accumulation points of poles on the second sheet of complex s plane, and are hence accumulation of singularities of T^I=1/2(s, t). For T^I=3/2(s, t), $s={\left({m}_{N}^{2}-{m}_{\pi }^{2}\right)}^{2}/{m}_{N}^{2}$ is the accumulation point of poles on the second sheet of the complex s plane. The proof is valid up to all orders of chiral expansions.

In recent several years, the tensor force, one of the most important components of the nucleon–nucleon force, has been implemented in time-dependent density functional theories and it has been found to influence many aspects of low-energy heavy-ion reactions, such as dissipation dynamics, sub-barrier fusions, and low-lying vibration states of colliding partners. Especially, the effects of tensor force on fusion reactions have been investigated from the internuclear potential to fusion crosssections systematically. In this work, we present a mini review on the recent progress on this topic. Considering the recent progress of low-energy reaction theories, we will also mention more possible effects of the tensor force on reaction dynamics.

We give a brief review on the formation and the calculation of black hole shadows. Firstly, we introduce the concept of a black hole shadow and the current works on a variety of black hole shadows. Secondly, we present the main methods of calculating photon sphere radius and shadow radius, and then explain how the photon sphere affects the boundary of black hole shadows. We review the analytical calculation for black hole shadows which have analytic expressions for shadow boundary due to the integrable photon motion system. And we introduce the fundamental photon orbits which can explain the patterns of black hole shadow shape. Finally, we review the numerical calculation of black hole shadows with the backward ray-tracing method and introduce some chaotic black hole shadows with self-similar fractal structures. Since the gravitational waves from the merger of binary black holes have been detected, we introduce a couple of shadows of binary black holes, which all have eyebrowlike shadows around the main shadows with the fractal structures. We discuss the invariant phase space structures of the photon motion system in black hole space-time, and explain the formation of black hole shadow is dominated by the invariant manifolds of certain Lyapunov orbits near the fixed points.

We investigate theoretically valley-resolved lateral shift of electrons traversing an n–p–n junction bulit on a typical tilted Dirac system (8-Pmmn borophene). A gauge-invariant formula on Goos–Hänchen (GH) shift of transmitted beams is derived, which holds for any anisotropic isoenergy surface. The tilt term brings valley dependence of relative position between the isoenergy surface in n region and that in the p region. Consequently, valley double refraction can occur at the n–p interface. The exiting positions of two valley-polarized beams depend on the incident angle and energy of incident beam and barrier parameters. Their spatial distance D can be enhanced to be ten to a hundred times larger than the barrier width. Due to tilting-induced high anisotropy of the isoenergy surface, D depends strongly on the barrier orientation. It is always zero when the junction is along the tilt direction of Dirac cones. Thus GH effect of transmitted beams in tilted Dirac systems can be utilized to design anisotropic and valley-resolved beam-splitter.

We conduct two group reductions of the Ablowitz–Kaup–Newell–Segur matrix spectral problems to present a class of novel reduced nonlocal reverse-spacetime integrable modified Korteweg–de Vries equations. One reduction is local, replacing the spectral parameter with its negative and the other is nonlocal, replacing the spectral parameter with itself. Then by taking advantage of distribution of eigenvalues, we generate soliton solutions from the reflectionless Riemann–Hilbert problems, where eigenvalues could equal adjoint eigenvalues.

In this work, a new superhard material named Pm BN is proposed. The structural properties, stability, mechanical properties, mechanical anisotropy properties, and electronic properties of Pm BN are studied in this work. Pm BN is dynamically and mechanically stable, the relative enthalpy of Pm BN is greater than that of c-BN, and in this respect, and it is more favorable than that of T-B₃N₃, T-B₇N₇, tP24 BN, Imm2 BN, NiAs BN, and rocksalt BN. The Young's modulus, bulk modulus, and shear modulus of Pm BN are 327 GPa, 331 GPa, and 738 GPa, respectively, and according to Chen's model, Pm BN is a novel superhard material. Compared with its original structure, the mechanical anisotropy of Young's modulus of Pm BN is larger than that of C14 carbon. Finally, the calculations of the electronic energy band structure show that Pm BN is a semiconductor material with not only a wide band gap but also an indirect band gap.

How to accurately probe chemically reactive flows with essential thermodynamic nonequilibrium effects is an open issue. Via the Chapman–Enskog analysis, the local nonequilibrium particle velocity distribution function is derived from the gas kinetic theory. It is demonstrated theoretically and numerically that the distribution function depends on the physical quantities and derivatives, and is independent of the chemical reactions directly as the chemical time scale is longer than the molecular relaxation time. Based on the simulation results of the discrete Boltzmann model, the departure between equilibrium and nonequilibrium distribution functions is obtained and analyzed around the detonation wave. In addition, it has been verified for the first time that the kinetic moments calculated by summations of the discrete distribution functions are close to those calculated by integrals of their original forms.

The entangled orbital angular momentum (OAM) photons propagating across a weakly turbulent atmosphere are investigated. Here, the paper uses the single-phase screen model based on the Kolmogorov theory of turbulence, and focuses on the influence of the backward scattering on OAM evolution. The results indicate that backward scattering plays an important role in the analysis of OAM entanglement evolution in the turbulent atmosphere. It cannot be negligible especially for higher-order OAM mode. Moreover, when OAM mode is greater than 4, entangled photon pairs composed of higher OAM modes are not more robust in turbulence within the weak scintillation regime. These results will be useful in future investigations of OAM-based optical wave propagation through turbulent atmosphere.

The spectrum of hadronic molecules composed of heavy–antiheavy charmed hadrons has been obtained in our previous work. The potentials are constants at the leading order, which are estimated from resonance saturation. The experimental candidates of hadronic molecules, say X(3872), Y(4260), three P_c states and P_cs(4459), fit the spectrum well. The success in describing the pattern of heavy–antiheavy hadronic molecules stimulates us to give more predictions for the heavy–heavy cases, which are less discussed in literature than the heavy–antiheavy ones. Given that the heavy–antiheavy hadronic molecules, several of which have strong experimental evidence, emerge from the dominant constant interaction from resonance saturation, we find that the existence of many heavy–heavy hadronic molecules is natural. Among these predicted heavy–heavy states we highlight the DD^* molecule and the ${D}^{(* )}{{\rm{\Sigma }}}_{c}^{(* )}$ molecules, which are the partners of the famous X(3872) and P_c states. Quite recently, LHCb collaboration reported a doubly charmed tetraquark state, T_cc, which is in line with our results for the DD^* molecule. With the first experimental signal of this new kind of exotic states, the upcoming update of the LHCb experiment as well as other experiments will provide more chances of observing the heavy–heavy hadronic molecules.

The magnetic properties and magnetocaloric effect of an antiferromagnetic/ferromagnetic (AFM/FM) BiFeO₃/Co bilayer with mixed-spin (5/2, 3/2) have been studied based on Monte Carlo simulation. The magnetization, susceptibility, and critical temperature are investigated under various exchange couplings and an external magnetic field. In particular, the influence of exchange couplings and an external magnetic field on the magnetic entropy change, adiabatic temperature change, and the relative cooling power (RCP) are studied. The simulation results indicated that the decrease of the exchange coupling and the increase of external magnetic fields can cause an increase of magnetic entropy change, adiabatic temperature change, and RCP. In addition, the hysteresis loops of the system are presented for different exchange couplings and temperatures.

In this paper, the Joule-Thomson expansion of the higher dimensional nonlinearly anti-de Sitter (AdS) black hole with power Maxwell invariant source is investigated. The results show the Joule-Thomson coefficient has a zero point and a divergent point, which coincide with the inversion temperature T_i and the zero point of the Hawking temperature, respectively. The inversion temperature increases monotonously with inversion pressure. For the high-pressure region, the inversion temperature decreases with the dimensionality D and the nonlinearity parameter s, whereas it increases with the charge Q. However, T_i for the low-pressure region increase with D and s, while it decreases with Q. The ratio $\eta$_BH between the minimum inversion temperature and the critical temperature does not depend on Q, it recovers the higher dimensional Reissner-Nördstrom AdS black hole case when s = 1. However, for s > 1, it becomes smaller and smaller as D increases and approaches a constant when D → ∞ . Finally, we found that an increase of mass M and s, or reducing the charge Q and D can enhance the isenthalpic curve, and the effect of s on the isenthalpic curve is much greater than other parameters.

This is a pedagogical review on ${T}\overline{{T}}$ deformation of two dimensional quantum field theories. It is based on three lectures which the author gave at ITP-CAS in December 2018. This review consists of four parts. The first part is a general introduction to ${T}\overline{{T}}$deformation. Special emphasises are put on the deformed classical Lagrangian and the exact solvability of the spectrum. The second part focuses on the torus partition sum of the ${T}\overline{{T}}$/${J}\overline{{T}}$ deformed conformal field theories and modular invariance/covariance. In the third part, different perspectives of ${T}\overline{{T}}$ deformation are presented, including its relation to random geometry, 2D topological gravity and holography. We summarize more recent developments until January 2021 in the last part.