December 12th, 2019

лошадь, диаграмма, Фейнман

Вклады КЭД высших порядков в рассеяние электрона на мюоне

Люблю такую науку! От диаграмм аж в глазах рябит:))

NNLO QED contribution to the μe→μe elastic scattering:

We present the current status of the Next-to-Next-to-Leading Order QED contribution to the μe-scattering. Particular focus is given to the techniques involved to tackle the virtual amplitude and their automatic implementation. Renormalization of the amplitude will be also discuss in details.
Comments: 9 pages, 5 figures, contribution to the Workshop on "Flavour changing and conserving processes" 2019 (FCCP2019), 29-31 August 2019, Villa Orlandi, Anacapri, Capri Island, Italy
лошадь, диаграмма, Фейнман

Об ускорителях

Electron Lenses, Tevatron and Selected Topics in Accelerators: 2019 Nishikawa Prize Talk:

Vladimir Shiltsev
This article is an extended version of the talk is given at the IPAC19 (Melbourne, Australia, May 2019) on the occasion of acceptance of the ACFA/IPAC19 Nishikawa Tetsuji Prize for a recent, significant, original contribution to the accelerator field, with no age limit with citation "...for original work on electron lenses in synchrotron colliders, outstanding contribution to the construction and operation of high-energy, high-luminosity hadron colliders and for tireless leadership in the accelerator community."
Comments: 25 pages, extended version of talk given at IPAC19 (Melbourne, Australia, May 2019)
лошадь, диаграмма, Фейнман

О расчетах дифракции

Похоже, нечто весьма простое и удобочитаемое.

Analytical Boundary-Based Method for Diffraction Calculations:

We present a simple method for calculation of diffraction effects in a beam passing an aperture. It follows the well-known approach of Miyamoto and Wolf, but is simpler and does not lead to singularities. It is thus shown that in the near-field region, i.e., at short propagation distances, most results depend on values of the beam's field at the aperture's boundaries, making it possible to derive diffraction effects in the form of a simple contour integral over the boundaries. For a uniform, i.e., plane-wave incident beam, the contour integral predicts the diffraction effects exactly. Comparisons of the analytical method and full numerical solutions demonstrate highly accurate agreement between them.
Comments: To be published in Journal of Optics
лошадь, диаграмма, Фейнман

Лекции Рубакова о космологии

Cosmology and Dark Matter:

Апдейт: а вот и комментарий Сергея Попова:
Серия хороших лекций. Написано на языке, доступном любому вменяемому студенту-физику старше второго курса (кроме, может 7-го параграфа). Начинается с основ космологии (отдельно отмечу, что очень понятно описаны барионнные акустические осцилляции), а потом подробно разбираются различные модели темного вещества.

Частично перекрывается с:

лошадь, диаграмма, Фейнман

Фейнмановская теория усилителя

Специально для nabbla1, зацени!

Searching for a response: the intriguing mystery of Feynman's theoretical reference amplifier:

We analyze Feynman's work on the response of an amplifier performed at Los Alamos and described in a technical report of 1946, as well as lectured on at the Cornell University in 1946-47 during his course on Mathematical Methods. The motivation for such a work was Feynman's involvement in the Manhattan Project, for which the necessity emerged of feeding the output pulses of counters into amplifiers or several other circuits, with the risk of introducing distortion at each step. In order to deal with such a problem, Feynman designed a theoretical "reference amplifier", thus enabling a characterization of the distortion by means of a benchmark relationship between phase and amplification for each frequency, and providing a standard tool for comparing the operation of real devices. A general theory was elaborated, from which he was able to deduce the basic features of an amplifier just from its response to a pulse or to a sine wave of definite frequency. Moreover, in order to apply such a theory to practical problems, a couple of remarkable examples were worked out, both for high-frequency cutoff amplifiers and for low-frequency ones. A special consideration deserves a mysteriously exceptional amplifier with best stability behavior introduced by Feynman, for which different physical interpretations are here envisaged. Feynman's earlier work then later flowed in the Hughes lectures on Mathematical Methods in Physics and Engineering of 1970-71, where he also remarked on causality properties of an amplifier, that is on certain relations between frequency and phase shift that a real amplifier has to satisfy in order not to allow output signals to appear before input ones. Quite interestingly, dispersion relations to be satisfied by the response function were introduced.
Comments: 19 pages, 6 figures