Article
Physics, Particles & Fields
Dharam Vir Ahluwalia, Julio M. Hoff da Silva, Cheng-Yang Lee
Summary: This article presents a formalism for mass dimension one fermions and bosons of spin one half, which are shown to be natural candidates for dark matter. The incorporation of rotational symmetry requires a two-fold Wigner degeneracy, effectively doubling the degrees of freedom. The developed framework provides a well-defined theory for mass dimension one fields of spin one half that are physically distinct from the Dirac field, and has potential implications for the cosmological constant problem and dark energy.
Article
Physics, Multidisciplinary
Chun-Hua Shu, Ke-Xin Zhang, Ke-Rong He, Hui Chen, San-Qiu Liu
Summary: The gravitational instability of dark-baryonic matter systems in the background of f (R) gravity is investigated using the Boltzmann-Vlasov equation. The study derives the dispersion relation considering the kappa-deformed Kaniadakis distribution using kinetic theory. It is found that in the high-frequency regime, an increase in kappa leads to an increase in the normalized frequency, while in the low-frequency regime, an increase in kappa results in a decrease in both the growth rate and the critical wave number. The study also examines the influence of dispersion velocity ratio and density ratio on the Jeans mass of dark-baryonic matter systems in f (R) gravity.
Article
Physics, Particles & Fields
A. Zahra, S. A. Mardan, I. Noureen
Summary: In this work, a generalized framework of the post-quasistatic approximation in higher dimensional non-comoving coordinates is proposed. The evolution of adiabatically radiating and dissipative fluid configuration in higher dimensional post-quasi-static approximation is studied. An iterative method for describing self-gravitating spheres is developed, with dissipation described by free-streaming radiation and heat flux. The matching of the higher dimensional interior and Vaidya exterior solutions in non-comoving coordinates results in the form of higher dimensional surface equations, which are significant for understanding physical phenomena at the boundary surface of gravitating sources such as luminosity, Doppler shift, and red-shift.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
P. S. Ens, A. F. Santos
Summary: This work presents a method to consider two originally different corrections to the Friedmann equations, namely the Barrow entropy and the f (R) gravity. By combining these two models, a modified Friedmann equation is obtained. An application using a specific f (R) model is investigated, with calculations of the state parameter and density parameters for matter and dark energy, leading to a discussion on the dynamic evolution of the universe.
Article
Physics, Multidisciplinary
Rabia Saleem, M. Israr Aslam, M. Zubair
Summary: In this study, the exact interior anisotropic solutions of compact stars are found under the f(T, T) gravity framework, considering Krori-Barua space-time. By evaluating the unknown model parameters through matching the exterior and interior space-time, it is observed that the results satisfy all necessary and sufficient physical conditions, making them physically viable.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Physics, Mathematical
Dan Wang, G. Mustafa
Summary: This paper examines embedded wormhole solutions in the modified f(R, T) theory of gravity, deriving class-1 solutions and exploring energy conditions. The obtained wormhole solutions are found to be acceptable as they violate the null energy condition in a specific region.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2021)
Article
Astronomy & Astrophysics
Mauricio Bellini, Luis Santiago Ridao
Summary: This paper investigates a preinflationary model where the background dynamics is driven by curvaton fluctuations. Two possible solutions with the same equation of state are explored, and conditions for a preinflationary scenario are obtained. The dynamics of gravitational waves and the ln(k)-spectrum of the scalar curvature on the extended manifold are also studied.
PHYSICS OF THE DARK UNIVERSE
(2022)
Article
Astronomy & Astrophysics
Akash Bose, Gopal Sardar, Subenoy Chakraborty
Summary: The present work focuses on cosmological solutions in f (R, T) gravity theory for a perfect fluid with a constant equation of state (omega). The study reveals that for a viable cosmological solution, omega is restricted to omega < 3, depending on the sign of an arbitrary constant. Two possible solutions are found: a finite universe model and an ever-expanding model of the universe. The field theoretic description of the model and the possibility of a ghost scalar field have been investigated. Additionally, an equivalence with modified Chaplygin gas has been demonstrated. Based on observational data, it is concluded that this model represents the evolution of the universe from a matter-dominated phase to the present accelerating phase.
PHYSICS OF THE DARK UNIVERSE
(2022)
Article
Astronomy & Astrophysics
Monica Jinwoo Kang, Craig Lawrie, Jaewon Song
Summary: A set of four-dimensional N 1/4 2 superconformal field theories labeled by simply laced Lie groups Gamma and G were studied, being constructed by gauging conformal matter SCFTs. The resulting theories have identical central charges for certain choices of Gamma and G, with Schur indices related to super-Yang-Mills theory. The theories can be seen as a generalization of affine quiver gauge theory obtained from probing singularities of type Gamma.
Article
Physics, Particles & Fields
Antonella Grassi, James Halverson, Cody Long, Julius L. Shaneson, Benjamin Sung, Jiahua Tian
Summary: This paper studies the 6D localized charged matter spectrum of F-theory on a singular elliptic Calabi-Yau 3-fold. By utilizing the technology of string junctions, the localized charged matter spectrum at intersections of seven-branes is determined, and the number of massless string junctions is computed. The results are in agreement with the predicted results from 6D anomaly cancellation.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Mathematical
Huseyin Aydin, Melis Ulu Dogru
Summary: This paper examines the massless scalar field using unimodular f(R) theory, solving field equations for a given spacetime with additional Bianchi identities and obtaining cylindrically symmetric black hole spacetimes. The analysis includes deriving equations of motion, depicting massless test particle orbits, and obtaining weak and strong energy conditions for the scalar field. Additionally, the stiff fluid interpretation of the scalar field is reviewed.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2021)
Article
Astronomy & Astrophysics
Hooman Davoudiasl, Peter B. Denton, David A. McGady
Summary: The conventional lore excludes fermionic dark matter with mass lighter than a few hundred electronvolts based on the Pauli exclusion principle. A new method is proposed in this paper which involves numerous quasi-degenerate species of fermions without couplings to the standard model to evade this bound. Gravitational interactions impose constraints from measurements at the LHC, cosmic rays, supernovae, and black hole spins and lifetimes, with a particular limit on the number of distinct species of particles being less than or around 10^62.
Article
Multidisciplinary Sciences
Ante Ravlic, Esra Yuksel, Tamara Niksic, Nils Paar
Summary: Properties of nuclei in hot stellar environments are explored using relativistic energy density functional theory. The study investigates the limits of nuclear existence at finite temperature and finds that the neutron drip line is significantly altered by temperature increase, especially near magic numbers. Surprisingly, the total number of bound nuclei increases with temperature due to thermal shell quenching.
NATURE COMMUNICATIONS
(2023)
Article
Astronomy & Astrophysics
Keiko Nagao, Hiroshi Okada
Summary: We study neutrinos and dark matter within the framework of a radiative seesaw scenario based on a gauged U(1)(R) symmetry. The dark matter is identified as a bosonic particle that interacts with the quark and lepton sectors through vector-like heavier quarks and leptons, and it also contributes to generating the neutrino mass matrix with neutral heavier fermions. Various constraints on the masses and couplings related to dark matter are explored by considering relic density, scattering cross sections for direct detection methods, neutrino oscillations, lepton flavor violations, and the muon anomalous magnetic moment. Additionally, we discuss semileptonic decays and neutral meson mixings that occur through the dark matter in one-loop box diagrams.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Physics, Multidisciplinary
G. Abbas, H. Nazar
Summary: This study explores new features of static anisotropic relativistic compact objects using f(R) theory of gravity, with two fluids distribution described by the MIT bag model equation of state. The physical credibility of the obtained solutions, including matter variables, energy conditions, hydrostatic equilibrium equation, and stability criterion, was analyzed using graphical representation. The proposed compact star candidate with two viable f(R) models was found to satisfy all conditions for a potentially stable configuration, suitable for testing strange star candidates.
Article
Astronomy & Astrophysics
Stefano Vignolo, Sante Carloni, Roberto Cianci, Fabrizio Esposito, Luca Fabbri
Summary: This study presents a tetrad-affine approach to investigate the coupling between f(Q) gravity and spinor fields of spin-1/2. Field equations and the conservation law of spin density are derived. The study focuses on Bianchi type-I cosmological models and provides a general procedure to solve the corresponding field equations. Analytical solutions are obtained in the case of f(Q) = alpha Q(n), showing isotropization at late times and the possibility of accelerated expansion depending on the exponent n.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Astronomy & Astrophysics
Luca Fabbri
Summary: We use the fourth-order differential theory of gravitation to address the issue of singularity avoidance, specifically studying the short-distance behavior in the case of black holes and the big bang.
Article
Multidisciplinary Sciences
Rodolfo Jose Bueno Rogerio, Luca Fabbri
Summary: In this paper, a new class of spin-half mass-dimension one fermions is obtained using the machinery introduced in Ahluwalia (Ahluwalia 2020. Phys. Eng. Sci. 476, 20200249. (doi:10.1098/rspa.2020.0249) and EPL 131, 41001. (doi:10.1209/0295-5075/131/41001)). These spinors, after a suitable dual structure examination, can serve as expansion coefficients for a local field.
PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2022)
Article
Multidisciplinary Sciences
Luca Fabbri
Summary: This article investigates the concepts of symmetry and its breakdown from two different perspectives. It discusses the universal asymmetry resulting from a special configuration in the first case, using an example from the standard model of particles and its consequences for cosmological scenarios. In the second case, it explores specific solutions for particle dynamics and an example of a toy model of entangled spins.
Article
Astronomy & Astrophysics
Luca Fabbri
Summary: This article discusses the theory of spinor fields in polar form, focusing on separating the true degrees of freedom of spinors from their Goldstone states. It is shown that these degrees of freedom contain information about rotation that is independent of gravitation. A model of entangled spins is constructed using this theory, where a singlet possesses a uniform rotation that collapses simultaneously regardless of spatial distance. Similar models of entangled polarizations are also discussed, along with an analogy to the double-slit experiment. General comments on Goldstone states are provided.
Article
Astronomy & Astrophysics
Fabrizio Esposito, Sante Carloni, Stefano Vignolo
Summary: By making use of the 1 + 3 covariant formalism, this study explicitly demonstrates the impact of nonmetricity on the dynamics of the Universe. Using the Dynamical System Approach, it analyzes the evolution of Bianchi type-I cosmologies within the framework of f(Q) gravity. The results show that different models of the function f(Q) can manifest isotropic eras of the Universe.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Physics, Multidisciplinary
Luca Fabbri
Summary: This article presents the theory of Dirac spinors in the formulation proposed by Bohm based on the idea of de Broglie. It re-writes the quantum relativistic matter field as a special type of classical fluid, demonstrating how a relativistic environment can encompass the non-local aspects of the hidden variables theory.
FOUNDATIONS OF PHYSICS
(2022)
Article
Mathematics, Applied
Luca Fabbri
Summary: In this article, we investigate tensorial connection for spinorial fields in polar form in various physical situations. We demonstrate that the tensorial connection is a useful tool in some cases, while in other cases, it is a necessary object. We compare and analyze different cases with a tensorial connection, exploring the analogies between space-time structures. Furthermore, we provide comments on quantum field theory and specific spinors.
ADVANCES IN APPLIED CLIFFORD ALGEBRAS
(2023)
Article
Astronomy & Astrophysics
Luca Fabbri
Summary: In this paper, we investigate the role of the torsion axial-vector in the dynamics of Dirac spinor fields. We demonstrate that the torsional correction leads to effects that regularize the otherwise singular distribution of spinorial matter fields. Finally, we provide comments on the implications for physics.
Article
Mathematics, Applied
Rodolfo Jose Bueno Rogerio, Luca Fabbri
Summary: In this paper, we investigate a versatile field propagator that can accommodate both newly-defined mass-dimension 1 fermions and spin-1/2 bosons. Our approach involves defining a mapping between spinors of different Lounesto classes and expressing the propagator in terms of the corresponding dual structures.
ADVANCES IN APPLIED CLIFFORD ALGEBRAS
(2023)
Article
Physics, Multidisciplinary
Luca Fabbri
Summary: We investigate the hydrodynamic formulation of quantum mechanics for relativistic spinor fields and find that the commonly defined velocity cannot accurately represent the tangent vector to particle trajectories. We propose an alternative definition for the tangent vector and hence particle trajectories, which we believe to be novel and unique. These findings are a crucial step towards addressing additional challenges such as defining trajectories for multi-particle systems or ensembles, as they have numerous applications and implications in quantum mechanics.
FOUNDATIONS OF PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Luca Fabbri, Camilla Bordoni, Pedro Barquinha, Jerome Crocco, Beatrice Fraboni, Tobias Cramer
Summary: The disordered microscopic structure of amorphous semiconductors leads to the formation of band tails in the density of states (DOS), which greatly affect charge transport properties. Kelvin Probe Force Microscopy (KPFM) is a powerful technique to measure the DOS, but lacks a model to interpret KPFM spectroscopy data on amorphous semiconductors of finite thickness. In this study, an analytical solution to the Poisson equation is provided for a metal-insulator-semiconductor junction interacting with the atomic force microscope tip, allowing for the fitting of experimental data and obtaining DOS parameters. This method was demonstrated on Indium-Gallium-Zinc Oxide (IGZO) thin-film transistors (IGZO-TFTs) and showed good agreement with values obtained from photocurrent spectroscopy.
Editorial Material
Astronomy & Astrophysics
Luca Fabbri
Article
Multidisciplinary Sciences
Luca Fabbri
Summary: This article discusses the re-formulation of relativistic spinor field theory in polar variables, allowing for interpretation in terms of fluid variables. The dynamics of spinor fields are then converted into a special type of spin fluid dynamics. The authors demonstrate that this conversion into dynamical spin fluid is not unique, but can be achieved through 19 different rearrangements, as evidenced by the 19 minimal systems of hydrodynamic equations equivalent to the Dirac equations.
Article
Physics, Multidisciplinary
Andre G. Campos, Luca Fabbri
Summary: In this study, the relativistic dynamical inversion technique is used to find analytical solutions to the Dirac equation in explicitly covariant form. The technique is demonstrated by making a change from Cartesian to spherical coordinates for a given Dirac spinor. The study also constructs a family of normalizable analytic solutions and identifies exact solutions for specific cases involving magnetic and electric fields.
PHYSICAL REVIEW RESEARCH
(2022)