August 27th, 2021

лошадь, диаграмма, Фейнман

Проект "Июльский зной"

Стадия 3 - акварель формата А5:


2021-08-21-акварель-шаг_4_corr.p © qedqed.iMGSRC.RU


Сравнение трех этапов: уголь, пастель, акварель:

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Опрос:

Стоит ли делать акварель А4?

да
4(66.7%)
нет
0(0.0%)
занимайся лучше наукой
2(33.3%)

Стоимт ли делать пастель А3?

да
3(60.0%)
нет
1(20.0%)
фотографируй лучше птичек
1(20.0%)
лошадь, диаграмма, Фейнман

Шикарный курс по ядру и частицам с широким охватом тем (и с задачами)

Как-то упустил в свое время...

A Somewhat Random Walk Through Nuclear and Particle Physics: https://arxiv.org/abs/2006.12564
Thomas D. Cohen, Nicholas R. Poniatowski
These notes are an outgrowth of an advanced undergraduate course taught at the University of Maryland, College Park. They are intended as an introduction to various aspects of particle and nuclear physics with an emphasis on the role of symmetry. The basic philosophy is to introduce many of the fundamental ideas in nuclear and particle physics using relatively sophisticated mathematical tools -- but to do so in as a simplified a context to explain the underlying ideas. Thus, for example, the Higgs mechanism is discussed in terms of an Abelian Higgs model. The emphasis is largely, but not entirely theoretical in orientation. The goal is for readers to develop an understanding of many of the underlying issues in a relatively sophisticated way.
Comments: 158 pages; submission to SciPost Lecture Notes
лошадь, диаграмма, Фейнман

Подсчет микросостояний парамагнетика с p состояниями

Отличная учебная задачка для курса статфизики (и не только).

Counting microstates of the p-state paramagnet: https://arxiv.org/abs/2108.10340
Steuard Jensen
One effective approach to introducing entropy and the second law is to study models with easily countable states at fixed energy. But such systems are rare: the only familiar examples are the Einstein solid and the two-state paramagnet, which limits the available questions for assignment or discussion. This work considers the more general case of the p-state paramagnet and describes the modestly more complicated counting of its microstates. By computing multiplicities in advance, an instructor can draw on these systems to assign a variety of new problems or open-ended projects that students can complete with the help of a spreadsheet program or analytic calculation.
Comments: 10 pages, 4 figures. Submitted to the American Journal of Physics
ФТФ, ХГУ

Дейтрон вечно актуален

Помню, как на старших курсах, когда я уже начал ходить в ХФТИ, меня впечатлил разработанный там способ измерения поляризации гамма-квантов: их использовали для фоторасщепления дейтронов и определяли поляризацию по асимметрии вылета продуктов этого расщепления! Фоторасщепление дейтрона обсуждается и в появившейся сегодня в арХиве чьей-то кандидатской:

Probing the Structure of Deuteron at Very Short Distances: https://arxiv.org/abs/2108.11502
Frank Vera
We study the electrodisintegration of deuteron at quasi-elastic kinematics and high transferred momentum as a probe for the short distance structure in nuclei. In this reaction, an electron hits a nucleus of deuterium, which breaks up into a proton-neutron pair. We focus our attention on events where fast nucleons emerge, corresponding to nuclear configurations where the bound nucleons have a high relative momentum (exceeding 700 MeV/c). The present research is relevant to physical systems where high-density nuclear matter is present. This condition covers a wide range of physics, from neutron stars to nuclei stability and the repulsive nuclear core.
The present work differs from previous studies in two crucial features. One is the definition of the deuteron wave function, which include terms of a relativistic origin that can be ordered based on their relative contribution to the deuteron's internal momentum distribution. These terms, related to the off-shell properties of the nucleon-nucleon bound-state, do not occur in non-relativistic quantum mechanics. However, they become increasingly important in describing configurations with a high nucleon-nucleon relative momentum. The second difference is that we account for the off-shell nature of the bound nucleon that enters on the definition of the (half-off-shell) electromagnetic current. We avoid many of the difficulties inherent to the relativistic nature of the processes involved by adopting a theoretical framework known as Light Front dynamics. Simultaneous simplifications in the definition of the relativistic wave function for the proton-neutron bound state and the treatment of the (half-off-shell) electromagnetic current for the bound nucleon are among the essential advantages resulting from the use of the Light Front dynamics.
Comments: PhD Thesis in Theoretical Nuclear Physics (Florida International University), 161 pages (excluding (11) initial pages: title, acknowledgment, table of contents, etc.), 29 figures
лошадь, диаграмма, Фейнман

Щурка с добычей

Снято днем ранее этих парадных портретов. Снято издалека, качество никакое, зато щурка видна в деле:


DSC_6690_щурка_с_добычей_corr.jp © qedqed.iMGSRC.RU


По-моему, это шмель:

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