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We introduce a generalized Lagrangian density - involving a non-Hermitian kinetic term - for a quantum particle with the generalized momentum operator. Upon variation of the Lagrangian, we obtain the corresponding Schr\"odinger equation.…

Quantum Physics · Physics 2022-03-07 M. Izadparast , S. Habib Mazharimousavi

The positivity of the energy in relativistic quantum mechanics implies that wave functions can be continued analytically to the forward tube T in complex spacetime. For Klein-Gordon particles, we interpret T as an extended (8D) classical…

Mathematical Physics · Physics 2009-10-14 Gerald Kaiser

We treat the probability distributions for quadratic quantum fields, averaged with a Lorentzian test function, in four-dimensional Minkowski vacuum. These distributions share some properties with previous results in two-dimensional…

Quantum Physics · Physics 2012-09-06 Christopher J. Fewster , L. H. Ford , Thomas A. Roman

Even though the Bohmian trajectories given by integral curves of the conserved Klein-Gordon current may involve motions backwards in time, the natural relativistic probability density of particle positions is well-defined. The Bohmian…

Quantum Physics · Physics 2010-05-12 H. Nikolic

We study a one-dimensional model of disordered electrons (also relevant for random spin chains), which exhibits a delocalisation transition at half-filling. Exact probability distribution functions for the Wigner time and transmission…

Disordered Systems and Neural Networks · Physics 2009-10-31 M. Steiner , Yang Chen , M. Fabrizio , Alexander O. Gogolin

Relativistic dynamics of distributed mass and charge densities of the extended classical particle is discussed for arbitrary gravitational and electromagnetic fields. Vector geodesic relations for material space densities are consequences…

General Physics · Physics 2012-12-04 I. E. Bulyzhenkov

For an electron, a spin-1/2 particle, the spin charge $\mathbf{s}$, a real pseudovector with constant length, could determine the spin polarization properties in quantum mechanics. Since spin density $\rho_{\mathbf{s}}$ could be expressed…

Mesoscale and Nanoscale Physics · Physics 2009-04-28 Xiang Zhou , Zhenyu Zhang , Cheng-Zheng Hu

In all-perpendicular spin valve nanopillars the probability density of the free-layer magnetization is independent of the azimuthal angle and its evolution equation simplifies considerably compared to the general, nonaxisymmetric geometry.…

Mesoscale and Nanoscale Physics · Physics 2017-08-08 Michail Tzoufras

In this paper we derive a fully relativistic kinetic theory for spin-1/2 particles and its coupling to Maxwell's equations, valid in the long scale-length limit, where the fields vary on a scale much longer than the localization of the…

Plasma Physics · Physics 2017-08-30 Robin Ekman , Felipe A. Asenjo , Jens Zamanian

We find the laws for the spreading of the spatial widths (parallel and transverse to the direction of average motion) of the relativistic position probability density for a massive, spinless particle. We find that when the momentum width of…

Quantum Physics · Physics 2018-04-04 Scott E. Hoffmann

Particles states transforming in one of the infinite spin representations of the Poincar\'e group (as classified by E. Wigner) are consistent with fundamental physical principles, but local fields generating them from the vacuum state…

Mathematical Physics · Physics 2017-09-20 Roberto Longo , Vincenzo Morinelli , Karl-Henning Rehren

We have described electron spin dynamics in the presence of the spin-orbit interaction and disorder using the spin-density matrix method. Exact solution is obtained for an arbitrary 2D spin-orbit Hamiltonian and arbitrary smoothness of the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Alexander Khaetskii

The wave spin of an electron can be fully characterized by the current density calculated from the exact four-spinor solution of the Dirac equation. In the excited states of the electron in a magnetic field-free quantum well, the current…

Quantum Physics · Physics 2023-03-21 Ju Gao , Fang Shen

The conventional Wigner function is inappropriate in a quantum field theory setting because, as a quasiprobability density over phase space, it is not manifestly Lorentz covariant. A manifestly relativistic variant is constructed as a…

Quantum Physics · Physics 2007-05-23 Peter Morgan

We present the exact form of the spin polarization vector and the spin density matrix of massive and massless free particles of any spin and helicity at general global equilibrium in a relativistic fluid with non-vanishing thermal…

Nuclear Theory · Physics 2023-06-16 Andrea Palermo , Francesco Becattini

In this study, energy backflow in the Poynting vector, as well as its orbital and spin current density components, has been examined for a 2-dimensional causal unidirectional vector-valued monochromatic electromagnetic wave. Linear…

Optics · Physics 2026-04-09 Peeter Saari , Ioannis Besieris

A recent complete, explicit classification of all locally constructed symmetries and currents for free spinorial massless spin s fields on Minkowski space is summarized and extended to give a classification of all covariant symmetry…

Mathematical Physics · Physics 2007-05-23 Stephen C. Anco , Juha Pohjanpelto

A spectral representation for the neutrino propagator in a moving matter with constant density is constructed. It is found that in a matter there exists a 4-dimensional axis of complete polarization, all poles of the propagator are…

High Energy Physics - Phenomenology · Physics 2017-11-22 D. M. Voronin , A. E. Kaloshin

We have described the electron spin dynamics in the presence of the spin-orbit interaction and disorder using the spin-density matrix method. We showed that in the Born approximation in the scattering amplitude the spin current is zero for…

Mesoscale and Nanoscale Physics · Physics 2015-06-24 Alexander Khaetskii

This work completes the program started in \cite{bb1,bb2,bb3} to derive the Heisenberg uncertainty relation for relativistic particles. Sharp uncertainty relations for massive relativistic particles with spin 0 and spin 1 are derived. The…

Quantum Physics · Physics 2021-06-03 Iwo Bialynicki-Birula , Adam Prystupiuk