Fortschritte Der Physik-Progress of Physics最新文献

In this article I consider type II superstring in the pure spinor formulation with constant background fields in the context of T-dualization. First, I prove that bosonic and fermionic T-dualization commute using already known T-dual transformation laws for bosonic and fermionic T-dualization. Consequently, the T-dual transformation laws of the full T-dualization are obtained. At the end, the full T-dualization is realized in double space and it is showed that Buscher procedure and double space approach are equivalent in this specific case.

The propagation of a massive scalar field and a massless Dirac field in the geometry of a dilaton–de Sitter black hole is investigated. Starting from the covariant perturbation equations, the corresponding effective potentials are presented and their dependence on the dilaton charge, field mass, and cosmological constant is analyzed. Using the WKB approximation, the grey-body factors are computed and the associated absorption cross-sections are studied. The results show that increasing the field mass or dilaton charge raises the effective potential barrier, leading to a suppression of transmission at low frequencies, while a larger cosmological constant lowers the barrier and enhances transmission. The partial absorption cross-sections for different multipole numbers display the expected oscillatory structure, with the lowest multipoles dominating at small frequencies. After summation over multipoles, the oscillations average out and the total cross-section interpolates between strong suppression in the infrared regime and the geometric capture limit at high frequencies. These findings provide a systematic description of scattering and absorption properties of dilaton–de Sitter black holes for both scalar and fermionic perturbations.

In this work, the interaction of circularly polarized gravitational waves (GWs) with electromagnetic (EM) fields. Circular perturbations of spacetime are assumed and the perturbed Maxwell equations are used as the starting point for all governing relations. Within this framework, modified evolution equations for the electric and magnetic fields, charge density, and the EM stress–energy tensor are derived. The results show that the GW amplitude $�h_c$ plays a central role. It determines the strength of oscillations in the charge density, controls the redistribution of stored EM energy, and modifies the flux of energy through both electric and magnetic sectors. The charge density acquires synchronized oscillations with the GW, while circular polarization produces a helical modulation pattern that directly reflects the GW helicity. The electric and magnetic fields show both static amplifications and oscillatory modulations, and the energy flux exhibits variations that depend on polarization. As $�h_c$ increases, the deviations from the unperturbed fields become more pronounced, leading to enhanced oscillations, stronger non-linear growth, and richer sideband structures in polarization dynamics. In general, this study provides a consistent and extended framework for understanding how GWs leave signatures on EM systems. The results suggest that even weak GWs imprint detectable modulations, while stronger perturbations reshape EM energy flow in a distinctive way. Such GW and EM couplings open up complementary possibilities for probing spacetime perturbations, with relevance to both astrophysical environments and controlled laboratory experiments designed for precision measurements.

Data are used from distinct sources like Dark Energy Survey five-year supernovae data (DES 5YR), patterns in galaxy distributions (BAO), and the rate at which the universe is expanding over time (OHD) to study the so-called Myrzakulov $��f�(�R�,�T�)�$ gravity (MG-I). This theory is a modified version of gravity that utilizes a special kind of connection to describe how space and time behave, including some additional features not found in Einstein's theory of general relativity. In this model, pressureless matter is considered to discuss the physical features of the model, which include a thermodynamic analysis. The model is interpreted to be in good agreement with the recent observational datasets. The model presents a continuous transition from a decelerating to an accelerating state at the low redshift. Additionally, the model is consistent with $��\Lambda �\mathrm{CDM}�$ at the early as well as final stages of the evolution of the Universe for joint datasets. The model exhibits Quintessence-like behavior in redshift and converges to $��\Lambda �\mathrm{CDM}�$ at the late times as $��z�\to �-�1�$ for all observations. The development of the total entropy, Hawking temperature, and the viability of the second law of thermodynamics are explored in the model according to the recent observational dataset.

This paper investigates quantum obesity, quantum discord, and the quantum steering ellipsoid (QSE) for bipartite Gisin states that are subjected to Garfinkle–Horowitz–Strominger (GHS) dilation of spacetime on the second qubit. These three quantifiers are introduced to characterize quantum correlations beyond entanglement and can also function as entanglement witnesses. A monotonic decrease in the physical accessibility of both quantum discord as demonstrate in the results and quantum obesity as the dilation parameter increases within the region-I of the second qubit. Conversely, in the anti-particle region, the accessibility of quantum discord and quantum obesity stabilizes at finite values of the dilation parameter owing to the influence of the Pauli exclusion principle and Fermi-Dirac statistics, subsequently increasing gradually. Notably, the QSE in the region-I expand as the Dirac field frequency rises and the dilation parameter diminishes, while the opposite trend is observed in the anti-particle region.

A primary goal of string phenomenology is to identify realistic four-dimensional physics within the landscape of string theory solutions. In F-theory, such solutions are encoded in the geometry of singular elliptic fibrations, whose study often requires particularly challenging and cumbersome computations. In this work, FTheoryTools is introduced, a novel software module integrated into the OSCAR computer algebra system, designed to automate the complex and tedious tasks involved in F-theory model building. Key features of FTheoryTools include the enumeration of $�G_4$-fluxes, the capability to perform blowups on arbitrary (including non-toric) loci, and a literature database of existing F-theory constructions employing a MaRDI-based data format for enhanced collaboration and reproducibility. As a demonstration of its power, a stress test is presented by applying FTheoryTools to the challenging F-theory geometry with most flux vacua [1]. The results illustrate the potential of FTheoryTools to streamline F-theory research and pave the way for future developments in the computational study of string phenomenology.