November 2nd, 2021

лошадь, диаграмма, Фейнман

Серия из двух статей об электромагнитных свойствах нейтрино

Electromagnetic neutrino: The basic processes and astrophysical probes:
Alexander Studenikin
After a brief reminder on the electromagnetic properties of neutrinos, the main processes of the electromagnetic interactions of neutrinos in astrophysics and the corresponding limitations on millicharges and effective magnetic moments of the particle are discussed.
Comments: 5 pages, 2 figures, based on the oral presentation at the 17th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2021), 26 August - 3 September 2021, hosted by IFIC Valencia and held online

Electromagnetic neutrinos: The theory and bounds from scattering experiments:
Alexander Studenikin
A brief overview of the electromagnetic properties of neutrinos is presented with a discussion of the most important fundamental aspects of the problem. Then using data from the ground-based reactor and solar neutrino-electron scattering experiments the best upper bounds on neutrino effective magnetic moments are discussed.
Comments: 6 pages in Latex, 1 figure, based on the oral presentation at the European Physical Society Conference on High Energy Physics, 26-30 July 2021, hosted jointly by Universität Hamburg and by the research center DESY and held online
лошадь, диаграмма, Фейнман

Большой и свежий обзор о форме банчей и ее формировании (каламбурчик-с:)))

Bunch Shaping in Electron Linear Accelerators:
G. Ha, K.-J. Kim, P. Piot, J.G. Power, Y. Sun
Modern electron linear accelerators are often designed to produce smooth bunch distributions characterized by their macroscopic ensemble-average moments. However, an increasing number of accelerator applications call for finer control over the beam distribution, e.g., by requiring specific shapes for its projection along one coordinate. Ultimately, the control of the beam distribution at the single-particle level could enable new opportunities in accelerator science. This review discusses the recent progress toward controlling electron beam distributions on the "mesoscopic" scale with an emphasis on shaping the beam or introducing complex correlations required for some applications. This review emphasizes experimental and theoretical developments of electron-bunch shaping methods based on bounded external electromagnetic fields or via interactions with the self-generated velocity and radiation fields.
Comments: 78 pages, 60 figues; submitted to the Review of Modern Physics
лошадь, диаграмма, Фейнман

Симпатичное по классической электродинамике от Эппа

Вычисляется поток углового момента (a.k.a. момента импульса) от движущегося точечного заряда.

Angular momentum transfered by the field of a moving point charge:
Vladimir Epp, Ulyana Guselnikova, Irina Kamenskaya
The flux of angular momentum of electromagnetic field of an arbitrarily moving point charge is investigated. General equations are obtained for the transfer of angular momentum at arbitrary distance from the charge, and corresponding equations in the far-field approximation. An explicit expression is obtained for the flux of angular momentum in the wave zone in terms of coordinates, velocity, and acceleration of the charge. The torque is calculated, that would act on an object if it absorbed all the radiation incident on it. It is shown that this torque is proportional to the curl of the stress tensor of the electromagnetic field; in the far field approximation the torque is proportional to the curl of the Poynting vector.
Comments: 18 pages, 6 figures
лошадь, диаграмма, Фейнман

Разложение произвольной вещественной матрицы по матрицам Паули

H2ZIXY: Pauli spin matrix decomposition of real symmetric matrices:
Rocco Monteiro Nunes Pesce, Paul D. Stevenson
We present a code in Python3 which takes a square real symmetric matrix, of arbitrary size, and decomposes it as a tensor product of Pauli spin matrices. The application to the decomposition of a Hamiltonian of relevance to nuclear physics for implementation on quantum computer is given.
Comments: 8 pages
лошадь, диаграмма, Фейнман

Очередная домашняя лаба по физике с использованием смартфона

A Low-Cost Analysis of Magnetic Multipoles via Theory, Experiment, and Simulation:
Antara Sen, M.C. Sullivan
Multipole expansions of electric charge and current distributions and the fields those multipoles create are a fundamental pillar of electromagnetic theory, but explanations and examples are rare beyond a dipole. In this paper we describe a low-cost exploration of magnetic multipoles. Using the field from ideal magnetic dipoles and a simple binomial approximation, we show that each multipole obeys B∝rn, with n=−3,−4,−5,−6 for a dipole, quadrupole, sextupole, and octupole, respectively. Using commercially available NdFeB magnets and the magnetic field sensor inside a smartphone, we experimentally verify the power-law dependence of the multipole configurations. Finally, the open-source Python library Magpylib can simulate the magnetic field of arbitrary permanent magnet distributions, which also shows the same power law dependence for the different multipole configurations.
Comments: 7 pages, 9 figures
лошадь, диаграмма, Фейнман

Учебно-методическое о связанных осциллятрорах, двухуровневой системе и фазе Берри

Study of geometric phase using classical coupled oscillators:
Sharba Bhattacharjee, Biprateep Dey, Ashok K Mohapatra
We illustrate the geometric phase associated with the cyclic dynamics of a classical system of coupled oscillators. We use an analogy between a classical coupled oscillator and a two-state quantum mechanical system to represent the evolution of the oscillator on an equivalent Hilbert space, which may be represented as a trajectory on the surface of a sphere. The cyclic evolution of the system leads to a change in phase, which consists of a dynamic phase along with an additional phase shift dependent on the geometry of the evolution. A simple experiment suitable for advanced undergraduate students is designed to study the geometric phase incurred during cyclic evolution of a coupled oscillator.
Comments: 13 pages, 10 figures