Modern Physics Letters A

By using the notion of extension of Kac–Moody algebras for higher-dimensional compact manifolds recently introduced, we show that for the two-torus ${𝕊}^1\times {𝕊}^1$ and the two-sphere ${𝕊}^2$, these extensions, as well as extensions of the Virasoro algebra can be obtained naturally from the usual Kac–Moody and Virasoro algebras. Explicit fermionic realizations are proposed. In order to have well-defined generators, beyond the usual normal ordering prescription, we introduce a regulator and regularize infinite sums by means of Riemann $\zeta$-function.

The light-front Schwinger model in the bosonized form is analyzed focusing on its global properties. We point out that the gauge invariance of the original fermionic form of the model is lost after bosonization. Consequently, the previously found theta-vacuum structure based on the residual large gauge transformation is actually not an intrinsic property of the bosonized form of the model. We analyze the corresponding field equations without any “gauge fixing” in both the light-front and space-like (“instant-form”) versions of the model and find the coinciding results: the axial-vector anomaly is automatically present and the spectrum of the model is given by a massive boson with the mass $e^2/\pi$. Finally, we characterize and critically assess properties of the bosonized LF Schwinger model, found in the previous studies.

In this paper, we have examined the magnetized strange quark matter (MSQM) distribution in the inhomogeneous anisotropic Einstein–Rosen universe model within the framework of $f(R,T)$ theory and General Relativity (GR) in order to investigate whether there was a magnetic field in the first moments of the universe. With the help of the arbitrary $F(r)$ function, we researched for solutions in both theories for various cases. We have seen that the cubic function $F(r)=r^3$ gives meaningful results in both theories. We have obtained magnetic field-free strange quark matter solutions for the quadratic and constant states of the arbitrary function $F(r)$. It is seen that the choice of geometry (selection of the $F(r)$ function) has an effect on the presence of the magnetic field. Finally, the physical results are examined on 3D graph.

In this paper, we investigate the Rényi holographic dark energy model with the interaction between dark energy and dark matter within the framework of the fractal cosmology in which the Hubble horizon is considered as the IR cutoff. In this setting, we derive the evolution equation of the Rényi holographic dark energy density parameter, the equation of state (EoS) parameter and deceleration parameter. We find that the model in the fractal cosmology can explain the accelerated expansion of the universe. In addition, we discuss the statefinder diagnosis of this model, plotting the curves of $r$ and $s$ with redshift $z$ and the evolutionary trajectories of $r-s$. We find that statefinder can ideally break the degeneracy of different coupling parameter values in this model. Moreover, we find that the statefinder pair $S_3^{(2)}$ performs better than $S_3^{(1)}$ and $r-s$ in this model.

This paper further studies the cosmological evolution and geometry diagnosis of Barrow holographic dark energy (BHDE) in the DGP braneworld, specifically, by choosing the interaction between dark energy and dark matter item. $Q_1=3H\xi {\rho }_{\mathrm{\text{de}}}$, $Q_2=3H\xi {\rho }_{\mathrm{\text{dm}}}$, $Q_3=3H\xi {\rho }_{{\mathrm{\text{de}}}^2}/({\rho }_{\mathrm{\text{de}}}+{\rho }_{\mathrm{\text{dm}}})$, $Q_4=3H\xi {\rho }_{{\mathrm{\text{dm}}}^2}/({\rho }_{\mathrm{\text{de}}}+{\rho }_{\mathrm{\text{dm}}})$ are discussed in the case of no interaction and four different interactions, the evolution laws of energy density parameters, deceleration parameters and EOS (equation of state) parameters of Barrow holographic dark energy. The results show that the Barrow holographic dark energy in the DGP braneworld conforms to the current cosmic evolution rule, already achieved the universe main ingredients from matter to the transition of energy, and explains the problem of cosmic acceleration. Further, in order to distinguish between the model and $\mathrm{\Lambda }$CDM model, this paper also geometrically diagnoses the model with the two ways of Statefinder hierarchy and Om$(z)$. From their respective evolution image you can see, these two kinds of diagnosis methods can not only distinguish different from $\mathrm{\Lambda }$CDM model, but also can intuitively reflect the coupling parameters that can significantly affect the dark energy model.

The quantal flux behaviors of the refractive process in the elastic scattering of ${}^{16}\mathrm{\text{O}}$ on different targets at 1503 MeV are analyzed based on the eikonal approximation. For their angular distributions, the optical model and the eikonal approximation calculations are performed and compared with each other. The shadow-surface decomposition is carried out to qualitatively assess the strength of the surface scattering relative to the shadow one. The transversal fluxes are calculated and negative values representing the refractive process are observed near the nuclear surface region. The peak value of the negative region is found capable of being a characteristic quantity to measure the strength of the refractive scattering. The transversal-flux-peak orbital angular momentum increases as the target mass number increases and can be a quantity characterizing the refraction. The corresponding impact parameter is found closer to the outer part of the potential surface region.

Quasifission barriers were studied in the superheavy region $104\le Z\le 126$ using different projectile-target combinations. The different entrance channels parameters on quasifission barriers give an insight into the formation of compound nuclei and quasifission process. The quasifission barriers are more systematic for ${\chi }_m=0.25{\chi }_{\mathrm{\text{CN}}}+0.75{\chi }_{\mathrm{\text{eff}}}$. The effect of compound nucleus fissility ${\chi }_{\mathrm{\text{CN}}}$ and effective entrance channel fissility ${\chi }_{\mathrm{\text{eff}}}$ on quasifission barriers were investigated. The quasifission barriers are strongly influenced by ${\chi }_{\mathrm{\text{CN}}}$ and ${\chi }_{\mathrm{\text{eff}}}$ entrance channel parameters. The detailed investigations of entrance channel parameters on quasifission barriers provide a thorough understanding of compound nuclei formation in the superheavy element in the region $104\le Z\le 126$. Eventually, this study helps in the selection of projectile-target combinations to synthesis of superheavy nuclei.

It is pointed out that the equivalence of the Nernst theorem and the heat capacity statement of the third law of thermodynamics can be mathematically proved through a simple method.

Currently, quantum signature protocols assume that all participants in the protocol (signers, verifiers, and arbitrators) should exhibit quantum capabilities. If quantum devices are lacking, the quantum signature protocol cannot be implemented. However, quantum devices are not widely used, and not all users can own quantum devices. Boyer et al. first proposed the concept of the semi-quantum environment. Zhao et al. proposed a semi-quantum signature protocol with double signers based on the W state. Yang et al. discovered that in the semi-quantum signature protocol with double signers developed by Zhao et al., an internal attacker could launch an impersonation attack during the verification and signature stages to capture the private key and use it to impersonate the user’s identity. In addition, the eavesdropper can obtain all the secret information of the signers by performing a man-in-the-middle attack. All three attack modes can pass the eavesdropping check. Hence, if these security problems are not solved, the signature of the semi-quantum signature protocol with double signers proposed by Zhao et al. cannot be completed safely. Therefore, based on Bell states, a new semi-quantum signature protocol of double signers was developed in this study. The proposed protocol not only resists impersonation attacks and man-in-the-middle attacks but also resists other common attack modes.