Fortschritte Der Physik-Progress of Physics最新文献

We formulate scalar field theories in a curved braided $�L_{\infty }$-algebra formalism and analyse their correlation functions using Batalin–Vilkovisky quantization. We perform detailed calculations in cubic braided scalar field theory up to two-loop order and three-point multiplicity. The divergent tadpole contributions are eliminated by a suitable choice of central curvature for the $�L_{\infty }$-structure, and we confirm the absence of UV/IR mixing. The calculations of higher loop and higher multiplicity correlators in homological perturbation theory are facilitated by the introduction of a novel diagrammatic calculus. We derive an algebraic version of the Schwinger–Dyson equations based on the homological perturbation lemma, and use them to prove the braided Wick theorem.

The authors compare the structures and methods in the theory of causal fermion systems with approaches to fundamental physics based on division algebras, in particular the octonions. It is found that octonions and, more generally, tensor products of division algebras come up naturally to describe the symmetries of the vacuum configuration of a causal fermion system. This is achieved by associating the real and imaginary octonion basis elements with the neutrino and charged sectors of the vacuum fermionic projector, respectively. Conversely, causal fermion systems provide octonionic theories with spacetime structures and dynamical equations via the causal action principle. In this way, octonionic theories and causal fermion systems complement each other.

In this work, the matching of the Vilkovisky–DeWitt effective action of quantum gravity is discussedwith an example of an ultra-violet complete theory of quantum gravity. The authors show how this matching enables a calculation of the local Wilson coefficients of the effective action. Several examples in string theory are provided. Moreover, the matching conditions within the context of the swampland program are discussed.

The authors show that in the $��f�\left(�Q�\right)�$ gravity with a non-metricity scalar $�Q$, the curvatures in Einstein's gravity, that is, the Riemann curvature constructed from the standard Levi-Civita connection, could not be excluded or naturally appear. The first observation is that even in $��f�\left(�Q�\right)�$ gravity, the conservation of the matter energy-momentum tensor is not described by the covariant derivatives in the non-metricity gravity but that is given by the Levi-Civita connection. The commutator of the covariant derivatives in Einstein's gravity inevitably induces the Riemann curvature. There is no symmetry nor principle which prohibits the Riemann curvature in non-metricity gravity. Based on this observation, the authors propose and investigate $��f�\left(Q,,,G\right)�$ gravity with the Gauss–Bonnet invariant $�G$ and its generalizations. The authors also show how $��f�\left(Q,,,G\right)�$ models realizing any given the Friedmann–Lemaître–Robertson– Walker (FLRW) spacetime can be reconstructed. The reconstruction formalism to cosmology is applied. Explicitly, the gravity models which realize slow roll or constant roll inflation, dark energy epoch as well as the unification of the inflation and dark energy are found. The dynamical autonomous system and the gravitational wave in the theory under investigation are discussed. It is found the condition that the de Sitter spacetime becomes the (stable) fixed point of the system.

A novel interpretation of Symmetry Topological Field Theories (SymTFTs) as theories of gravity is explored by proposing a holographic duality where the bulk SymTFT (with the gauging of a suitable Lagrangian algebra) is dual to the universal effective field theory (EFT) that describes spontaneous symmetry breaking on the boundary. The authors tested this conjecture in various dimensions and with many examples involving different continuous symmetry structures, including non-Abelian and non-invertible symmetries, as well as higher groups. For instance, many Abelian SymTFTs are found to be dual to free theories of Goldstone bosons or generalized Maxwell fields, while non-Abelian SymTFTs relate to non-linear sigma models with target spaces defined by the symmetry groups. The analysis is also extended to include the non-invertible $��Q�/�Z�$ axial symmetry, which is shown to be dual to axion-Maxwell theory, and a non-Abelian 2-group structure in four dimensions, deriving a new parity-violating interaction that has implications for the low-energy dynamics of $��U�\left(�N�\right)�$ QCD.

Recent no-go theorems have ruled out four-dimensional classical de Sitter vacua in heterotic string theory. On the other hand, the absence of a well-defined Wilsonian effective action and other related phenomena also appear to rule out such time-dependent vacua with de Sitter isometries, even in the presence of quantum corrections. In this note, the authors argued that a four-dimensional de Sitter space can still exist in $��S�O�\left(�32�\right)�$ heterotic string theory as a Glauber–Sudarshan state, i.e., as an excited state, over a supersymmetric Minkowski background, albeit within a finite temporal domain. Borel resummation and resurgence play a crucial role in constructing such a state in the Hilbert space of heterotic theory governed entirely by the IR degrees of freedom.

In this article, the T-dualization of a 3D closed bosonic string, that is propagating in space-time metric with an infinitesimal linear dependence on the coordinates x^μ, is considered. Other fields, Kalb-Ramond and dilaton fields are set to zero. Action with this configuration of fields is not invariant to translations. In order to find the T-dual theory, a generalization of the Buscher procedure is employed, that can be applied to cases with coordinate dependent fields that do not possess translational isometry. Finally, by using transformation laws that connect coordinates of starting and T-dual theories, authors will be able to examine the geometric structure of T-dual theory.

A recent development involves an intriguing model of a quantum-corrected black hole, established through the application of the quantum Oppenheimer–Snyder model within loop quantum cosmology [Lewandowski et al., Phys. Rev. Lett. (2023) 130, 101501]. Employing both time-domain integration and the Wentzel–Kramers–Brillouin (WKB) approach, the quasinormal frequencies for scalar, electromagnetic, and neutrino perturbations in these quantum-corrected black holes are computed. This analysis reveals that while the real oscillation frequencies undergo only minor adjustments due to the quantum parameter, the damping rate experiences a significant decrease as a result of its influence. The author also deduced the analytic formula for quasinormal frequencies in the eikonal limit and showed that the correspondence between the null geodesics and eikonal quasinormal modes holds in this case.

In this study, the geometrically deformed compact objects in the f(Q, T) gravity theory under an electric field through gravitational decoupling via minimal geometric deformation (MGD) technique are developed for the first time. The decoupled field equations are solved via two different mimic approaches $��{\Theta }_0^0�=�\rho �$ and $��{\Theta }_1^1�=�p_r�$ through the Karmarkar condition. Physical viability tests are conducted on our models and examine how decoupling parameters affect the physical qualities of objects. The obtained models are compared with the observational constraints for neutron stars PSR J1810+174, PSR J1959+2048, and PSR J2215+5135, including GW190814. Particularly, by modifying parameters α and n, the occurrence of a “mass gap” component is accomplished. The resulting models exhibit stable, well-behaved mass profiles, regular behavior and no gravitational collapse, as verified by the Buchdahl–Andréasson's limit. Furthermore, a thorough physical analysis that is based on two parameters: n (f(Q, T)–coupling parameter) and α (decoupling parameter) is provided. This work extends our current understanding of compact star configurations and sheds light on the behavior of compact objects in the f(Q, T) gravity.