November 12th, 2019

лошадь, диаграмма, Фейнман

О рассеянии нейтрино электроном

В начале - хороший обзор со ссылками. А что такое "эффективная теория поля", которую сейчас постоянно упоминают, до сих пор руки не доходят разобраться, может теперь... :)

How well do we know neutrino-electron scattering? EFT approach:

We determine the effective theory of neutrino-electron and neutrino-quark scattering and provide the most precise up-to-date prediction for neutrino-electron scattering cross sections quantifying errors for the first time to be of order 0.2−0.4 %. Radiative corrections in the theory with electron and neutrinos only involve three effective couplings. One is the Fermi constant which is known with sub-ppm accuracy. Another one has a small error of order 0.02 %. The uncertainty of the third one is limited by the knowledge of hadronic contributions to charge-isospin vector-vector correlation function.
Comments: 5 pages, 3 figures, conference proceedings
лошадь, диаграмма, Фейнман

Демонстрация миражей

Temperature profile and double images in the inferior mirage:

Desert mirages were simulated in the laboratory by heating a flat surface of sand. This showed that a boundary layer of air, of only a few millimeters immediately covering a heated surface has nearly the same thickness over a wide range of temperatures. It consists of a region producing an inverted image, and another producing an erect image depending on the relative distances between observer, heated surface and object. Measurement of distances and heights show angles of incidence greater than angles of reflection. Air refractive index measurements agree with involvement of the critical angle in ray bending. An analogy with density gradient sucrose solutions also shows double images, inverted and erect. It is assumed that a similar situation exists outdoors. Specular reflection over rough surfaces can be described as a mirage, but it is seen at a wider range of viewing angles, and it does not require a temperature gradient. It is always present, but it can be obliterated by a higher intensity of diffuse reflection.
Comments: 19 pages, 16 figures