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In our previous work we have constructed a model of noncommutative (NC) gravity based on $SO(2,3)_\star$ gauge symmetry. In this paper we extend the model by adding matter fields: fermions and a $U(1)$ gauge field. Using the enveloping…

High Energy Physics - Theory · Physics 2018-08-01 Marija Dimitrijević Ćirić , Dragoljub Gočanin , Nikola Konjik , Voja Radovanović

We propose an explicit spin-foam amplitude for Lorentzian gravity in three dimensions, allowing for both space- and time-like boundaries. The model is based on two main requirements: that it should be structurally similar to its well-known…

General Relativity and Quantum Cosmology · Physics 2024-09-04 José Diogo Simão

A geometric formalism is developed which allows to describe the non-linear regime of higher-spin gravity emerging on a cosmological quantum space-time in the IKKT matrix model. The vacuum solutions are Ricci-flat up to an effective vacuum…

High Energy Physics - Theory · Physics 2020-09-23 Harold C. Steinacker

An analysis is made within the quantum formalism of the probabilistic features of the electron spin correlation, with the purpose of clarifying the concepts of contextuality and measurement dependence. The quantum formulas for the spin…

Quantum Physics · Physics 2022-07-07 Ana María Cetto

The thickness dependence of spin-orbit torque and magnetoresistance in ferromagnet/heavy-metal bilayers is studied using the first-principles non-equilibrium Green's function formalism combined with the Anderson disorder model. A systematic…

Mesoscale and Nanoscale Physics · Physics 2020-01-22 K. D. Belashchenko , Alexey A. Kovalev , M. van Schilfgaarde

We explore the limitations and validity of semi-classically formulated spin equations of motion. Using a single-molecule magnet as a test model, we employ three qualitatively different approximation schemes. From a microscopic model, we…

Mesoscale and Nanoscale Physics · Physics 2017-12-13 Henning Hammar , Jonas Fransson

In this article we review the present status of the spin foam formulation of non-perturbative (background independent) quantum gravity. The article is divided in two parts. In the first part we present a general introduction to the main…

General Relativity and Quantum Cosmology · Physics 2017-08-23 Alejandro Perez

Within a gauge formulation of 3+1 gravity relying on a nonlinear realization of the group of isometries of space-time, a natural expansion of the metric tensor arises and a simple choice of the gravity dynamical variables is possible. We…

General Relativity and Quantum Cosmology · Physics 2016-11-09 J. Julve , A. Tiemblo

We review the construction of Lagrangians for higher spin fields of mixed symmetry in the framework of graded geometry. The main advantage of the graded formalism in this context is that it provides universal expressions, in the sense that…

High Energy Physics - Theory · Physics 2024-06-11 Athanasios Chatzistavrakidis , Georgios Karagiannis , Peter Schupp

This article reviews basic theoretical features of Gilbert magnetization dynamics of a single domain magnetic film in the presence of Slonczewski spin-transfer torques, with and without thermal fluctuations taken into account. Rather than…

Materials Science · Physics 2007-05-23 Neil Smith

Starting from the Dirac-Kohn-Sham equation we derive the relativistic equation of motion of spin angular momentum in a magnetic solid under an external electromagnetic field. This equation of motion can be written in the form of the…

Materials Science · Physics 2016-10-20 Ritwik Mondal , Marco Berritta , Peter M. Oppeneer

We show how it is possible to formulate Euclidean two-dimensional quantum gravity as the scaling limit of an ordinary statistical system by means of dynamical triangulations, which can be viewed as a discretization in the space of…

High Energy Physics - Theory · Physics 2009-10-28 J. Ambjorn , J. Jurkiewicz , Y. Watabiki

In this paper we show that the spin transfer torque can be described by a pseudo magnetic field, proportional to the magnetic moment of the itinerant electrons that enters the Landau-Lifshitz-Gilbert equation in the same way as other…

Mesoscale and Nanoscale Physics · Physics 2008-11-24 Sayeef Salahuddin , Deepanjan Datta , Supriyo Datta

A first-order formulation of gravity is developed in which the fundamental fields consist of an SL(2,C) connection and two spinor-valued 1-forms. It is shown that the first term of an expansion of the Einstein-Hilbert action leads to an…

General Relativity and Quantum Cosmology · Physics 2018-11-06 Nicolas Ivancevic

Spin transport driven by the temperature gradient in ferromagnetic metals is studied based on a microscopic theory. It is shown that the temperature gradient works as an effective field equivalent to the electric field as for both the spin…

Mesoscale and Nanoscale Physics · Physics 2015-05-19 Yuu Takezoe , Kazuhiro Hosono , Akihito Takeuchi , Gen Tatara

A method is presented to calculate the spin relaxation times T1, T2 due to a non-uniform magnetic field, and the linear-in-electric-field precession frequency shift {\delta}{\omega}E when an electric field is present, in the diffusion…

Atomic Physics · Physics 2015-05-20 Steven M. Clayton

We study the coupling of massive fermions to the quantum mechanical dynamics of spacetime emerging from the spinfoam approach in three dimensions. We first recall the classical theory before constructing a spinfoam model of quantum gravity…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Winston Fairbairn

A recent article by Stiles et al. (cond-mat/0702020) argued in favor of the Landau-Lifshitz damping term in the micromagnetic equations of motion over that of the more commonly accepted Gilbert damping form. Much of their argument revolved…

Other Condensed Matter · Physics 2007-06-13 Neil Smith

Motivated by establishing holographic renormalization for gravitational theories with non-metricity and torsion, we present a new and efficient general method for calculating Gibbons-Hawking-York (GHY) terms. Our method consists of…

High Energy Physics - Theory · Physics 2023-05-03 Johanna Erdmenger , Bastian Heß , Ioannis Matthaiakakis , René Meyer

We consider general, non-linear curvature perturbations on scales greater than the Hubble horizon scale by invoking an expansion in spatial gradients, the so-called gradient expansion. After reviewing the basic properties of the gradient…

Astrophysics · Physics 2009-10-09 Misao Sasaki
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