December 21st, 2020

лошадь, диаграмма, Фейнман

Тестирование физических теорий с помощью статистики

Короткий текст с жутким количеством соавторов. Вдруг будет полезно уважаемому polenadisto?

Simple and statistically sound strategies for analysing physical theories: https://arxiv.org/abs/2012.09874

Physical theories that depend on many parameters or are tested against data from many different experiments pose unique challenges to parameter estimation. Many models in particle physics, astrophysics and cosmology fall into one or both of these categories. These issues are often sidestepped with very simplistic and statistically unsound ad hoc methods, involving naive intersection of parameter intervals estimated by multiple experiments, and random or grid sampling of model parameters. Whilst these methods are easy to apply, they exhibit pathologies even in low-dimensional parameter spaces, and quickly become problematic to use and interpret in higher dimensions. In this article we give clear guidance for going beyond these rudimentary procedures, suggesting some simple methods for performing statistically sound inference, and recommendations of readily-available software tools and standards that can assist in doing so. Our aim is to provide physicists with recommendations for reaching correct scientific conclusions, with only a modest increase in analysis burden.
Comments: 10 pages, 3 figures
лошадь, диаграмма, Фейнман

Дибарионные резонансы в столкновении двух протонов

Кажется, довольно понятная статейка.

P-wave dibaryon resonances in pp elastic scattering and near-threshold pion production: https://arxiv.org/abs/2012.09886

O.A. Rubtsova, V.I. Kukulin, M.N. Platonova
It is demonstrated within the dibaryon-induced model for NN interaction that pp scattering in P waves is governed mainly by the production of the intermediate dibaryon resonances. Two dibaryon resonances with a mass of about 2200 MeV discovered recently by the ANKE-COSY Collaboration are shown to determine both elastic pp phase shifts and inelasticities in the 3P0 and 3P2-3F2 channels from zero energy up to Tp=0.7-0.9 GeV. It is also demonstrated clearly that the 3P0 dibaryon plays a decisive role in near-threshold neutral pion production in pp collisions which is poorly understood to date. The missing dibaryon contribution is found to be the very possible reason for the failure of traditional approaches to explain near-threshold π0 production.
Comments: 12 pages, 11 figures; version accepted for publication in PRD
лошадь, диаграмма, Фейнман

Радиационные поправки в КЭД: сборник докладов

CFNS Ad-Hoc meeting on Radiative Corrections Whitepaper: https://arxiv.org/abs/2012.09970

Current precision scattering experiments and even more so many experiments planed for the Electron Ion Collider will be limited by systematics. From the theory side, a fundamental source of systematic uncertainty is the correct treatment of radiative effects. To gauge the current state of technique and knowledge, help the cross-pollination between different direction of nuclear physics, and to give input to the yellow report process, the community met in an ad-hoc workshop hosted by the Center for Frontiers in Nuclear Science, Stony Brook University. This whitepaper is a collection of contributions to this workshop.
лошадь, диаграмма, Фейнман

Диагностика пучка эксперименте по плазменному ускорению AWAKE

Beam Diagnostics in the Advanced Plasma Wakefield Experiment AWAKE: https://arxiv.org/abs/2012.10097
A.-M. Bachmann, P. Muggli, AWAKE Collaboration
In AWAKE a self-modulated proton bunch drives wakefields in a plasma. Recent experiments successfully demonstrated many aspects of the self-modulation of the drive bunch as well as acceleration of test electrons. Next experiments will focus on producing a multi-GeV accelerated electron bunch with low emittance and low energy spread. The experiment requires a variety of advanced beam diagnostics to characterize the self-modulated proton bunch at the picosecond time scale. These include optical transition radiation and a streak camera for short and long time scale detailed imaging of self-modulation and hosing, coherent transition radiation for modulation frequency measurements in the 100-300 GHz frequency range and multiple fluorescent screens for core and halo measurements. An overview of these diagnostics will be given.
Comments: 6 pages, 5 figures, submitted to IBIC 2020 conference proceedings
лошадь, диаграмма, Фейнман

Снова о радиационной безопасности полета на Марс

Среди авторов - мой любимый Луис Анчордоки:))

Health threat from cosmic radiation during a manned mission to Mars: https://arxiv.org/abs/2012.09604
Alexandra D Bloshenko, Jasmin M. Robinson, Rafael A. Colon, Luis A. Anchordoqui
Cosmic radiation is a critical factor for astronauts' safety in the context of evaluating the prospect of future space exploration. The Radiation Assessment Detector (RAD) on board the Curiosity Rover launched by the Mars Scientific Laboratory mission collected valuable data to model the energetic particle radiation environment inside a spacecraft during travel from Earth to Mars, and is currently doing the same on the surface of Mars itself. The Martian Radiation Experiment (MARIE) on board the Mars Odyssey satellite provides estimates of the absorbed radiation dose in the Martian orbit, which are predicted to be similar to the radiation dose on Mars' surface. In combination, these data provide a reliable assessment of the radiation hazards for a manned mission to Mars. Using data from RAD and MARIE we reexamine the risks for a crew on a manned flight to Mars and discuss recent developments in space exploration.
Comments: 8 pages, 2 figures, ICRC2021
лошадь, диаграмма, Фейнман

Популярная заметка об источнике звездной энергии

Общеизвестные вещи, но вдруг кому-то пригодится.

Children of the Stars: https://arxiv.org/abs/2012.09568
Henri Boffin
Even if it tends to hide more often in the current autumnal season, our host star, the Sun, is the principal source of energy on our planet. It has a luminosity of 3.828e26 Watts, and despite that we receive only 2 parts per billion of this, it allows for the Earth's life to thrive. Moreover, we know that the Sun has been shining in the same way for about 4.6 billion years (the age of the Earth) and will likely still do the same for another 5 billion years or so. The Sun's power engine, as well as the one of all the stars we see in the night sky, has for long been a mystery, but astronomers now have a good understanding of it.
Comments: A popular account of fusion in stars

Апдейт: на следующий день появилась большая статья, там в середине есть раздел со стандартной моделью Солнца:

A closer look at the pp-chain reaction in the Sun: Constraining the coupling of light mediators to protons: https://arxiv.org/abs/2012.11620

Anna M. Suliga, Shashank Shalgar (Niels Bohr Institute), George M. Fuller (University of California, San Diego)
The pp-chain of nuclear reactions is the primary route for energy production in the Sun. The first step in that reaction sequence converts two protons to a deuterium nucleus with the emission of a positron and electron neutrino. This reaction is extremely slow because it is a weak interaction, and significantly, it involves quantum tunneling through the Coulomb barrier. Though the reaction rate can be calculated with high confidence in the Standard Model, it has not been measured at solar energies. If there exist interactions that are engendered by non-standard mediators then the rate of this reaction in the Sun could be altered. We probe such non-standard interactions between two protons by performing self-consistent calculations of solar evolution to the current solar system age and then comparing to measured properties of the Sun, including solar neutrino results. We thereby obtain constraints on mediator mass and couplings in these beyond-standard-model scenarios. Constraints on these non-standard parameters could be extended further with better confidence on the value of the metallicity of the Sun and the solar neutrino CNO flux.
Comments: 22 pages, 5 figures