Article
Mathematics, Applied
Sam Chow, Sofia Lindqvist, Sean Prendiville
Summary: This paper establishes the partition regularity of the generalized Pythagorean equation in five or more variables, and shows the validity of Rado's characterization for equations in the set of positive kth powers with a sufficient number of variables. The research fully describes which diagonal forms are partition regular and which are not, with enough variables. Additionally, a supersaturated version of Rado's theorem for a linear equation restricted to squares minus one or logarithmically-smooth numbers is proven.
JOURNAL OF THE EUROPEAN MATHEMATICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Valentina Giangreco M. Puletti, Victoria L. Martin
Summary: In this study, we investigated how hidden conformal symmetry is manifested in the dynamics of a massless probe scalar field on a Kerr background beyond the Klein-Gordon equation. We used the monodromy method to study the analytic structure of the higher derivative equations of motion. We also explored the possibility of a Kerr/logCFT correspondence based on the presence of higher derivative dynamics in known examples of holographic AdS/logCFT correspondences.
Article
Astronomy & Astrophysics
Pengfei Zhang, Wen-Bin Shen, Chenxiang Wang, Ziyu Shen, Chenghui Cai, Xiao Sun, Wei Xu, Rui Xu, Abdelrahim Ruby, Mostafa Ashry
Summary: This study analyzes the effects of the ionosphere on frequency transfer between a space station and a ground-based station. The results show that the second-order ionospheric frequency shift needs to be considered and eliminated, but the third-order term does not need to be considered. The use of dual-frequency or tri-frequency combination methods can improve the accuracy of the gravitational redshift (GRS) test.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Mathematics
Flank D. M. Bezerra, Lucas A. Santos
Summary: In this paper, the characterization of the fractional powers of a class of positive operators using Chebyshev polynomials of the second kind is shown. The higher order abstract Cauchy problem with specific initial conditions and the operator in separable Hilbert space are considered.
MATHEMATISCHE ANNALEN
(2022)
Article
Astronomy & Astrophysics
Karim Mosani, Dipanjan Dey, Pankaj S. Joshi
Summary: This study investigates the global visibility of singularities as an end state of the gravitational collapse of spherically symmetric pressureless clouds. It shows the existence of a set of specific parameters that lead to physically strong globally visible singularities. This paper aims to demonstrate that globally visible singularities can form in astrophysical setups under appropriate circumstances.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Mathematics
Cecile Gachet
Summary: In this article, it is proved that a smooth projective variety is a Fano variety if the third, fourth, or (n-1)-th exterior power of its tangent bundle is strictly nef. Moreover, a classification for such varieties is provided when ρ(X)≠1.
INTERNATIONAL MATHEMATICS RESEARCH NOTICES
(2023)
Article
Mathematics
Kunlathida Muangma, Kijti Rodtes
Summary: This paper explores conditions for matrices expressed as sums of kth powers, expanding the existing research scope.
LINEAR & MULTILINEAR ALGEBRA
(2022)
Article
Physics, Particles & Fields
V. P. Vandeev, A. N. Semenova
Summary: The article explores tidal forces near the Kottler black hole, finding solutions for geodesic deviation equations of radially falling bodies and determining the asymptotic behavior of spatial geodesic deviation vector components. It reveals that the radial component of the tidal force changes sign outside the single event horizon for any negative cosmological constant, contrasting with the Schwarzschild black hole where all components have constant signs. Additionally, similarities between the Kottler and Reissner-Nordstrom black holes are identified based on the cosmological constant values that determine the existence of two horizons and changing sign of tidal force components. The non-analytical behavior of geodesic deviation vector components in anti-de Sitter spacetime is also detected and described locally.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Suvikranth Gera, Sandipan Sengupta
Summary: The model explores the relationship between gravity and electric charge, with the charge's characteristics evaluated using an index. The gravitational equations at this phase are equivalent to electrostatic laws, with finite field energy and regular geometry sourcing the charge.
Article
Astronomy & Astrophysics
Sougato Bose, Anupam Mazumdar, Martine Schut, Marko Toros
Summary: This paper emphasizes the importance of the quantum nature of the gravitational interaction with matter in generating entanglement of masses. By utilizing quantum perturbation theory, the critical assumptions for the quantum matter-matter interaction are identified and it is shown that a classical gravitational field cannot produce entanglement. Two examples are considered, demonstrating that it is the quantum properties of gravitons interacting with harmonic oscillators that lead to the creation of entangled states.
Article
Physics, Particles & Fields
C. R. Muniz, V. B. Bezerra, J. M. Toledo
Summary: Investigated Casimir effect between parallel plates around rotating Damour-Solodkhin and Teo wormholes, calculating energy density and comparing results to distinguish characteristics of different types of wormholes and black holes. Discussed Casimir effect in various wormhole spacetimes, as well as influence of gravito-inertial and frame dragging effects on vacuum quantum fluctuations.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
N. P. Meshcheriakov, V. V. Shatalova, K. V. Stepanyantz
Summary: We investigate the coefficients at powers of logarithms present in the renormalization constants for renormalizable theories with a single coupling constant regularized by higher derivatives. We construct general explicit expressions for the coefficients and relate them to the fi-function and anomalous dimension. The correctness of the results is checked by comparing them with a four-loop calculation for N = 1 supersymmetric quantum electrodynamics and by deriving a relation between the renormalization constants.
Article
Physics, Particles & Fields
Rashmi Uniyal
Summary: This study investigates the tidal forces and their impact on a Schwarzschild black hole surrounded by clouds of strings and quintessence. It is found that the event horizon of the black hole shrinks as the parameters of the string cloud and quintessence increase. The tidal forces exerted on the radial and angular directions are independent of the string cloud parameter a. Geodesic deviation equations are formulated and solved for this black hole metric, with two different initial conditions applied for numerical analysis. The results are compared with those obtained from the Schwarzschild black hole metric.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Particles & Fields
Shobhit Giri, Hemwati Nandan, Lokesh Kumar Joshi, Sunil D. Maharaj
Summary: This study examines the stability of circular orbits in a traversable wormhole spacetime and employs the Lyapunov stability approach to determine the motion characteristics of non-spinning test particles in this spacetime.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Multidisciplinary
Rakesh Raushan, S. Angit, R. Chaubey
Summary: The study focuses on the dynamical evolution of a flat FRW cosmological model with variable equation of state in Lyra geometry, investigating phase-plane analysis and utilizing dynamical system techniques to study the evolution of cosmological solutions. The stability and viability of the model are discussed using linear Jacobian stability analysis for hyperbolic equilibrium points and center manifold theory for non-hyperbolic equilibrium points.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)