June 11th, 2021

лошадь, диаграмма, Фейнман

Только что узнал, что Болотовский умер :(((

Борис Михайлович Болотовский (20.09.1928 — 28.05.2021).

Это был воистину великий человек, настоящий гений классической электродинамики, "недооцененный гений" по оценке моего любимого шефа, один из оппонентов моей докторской, на редкость симпатичный и приятный в общении человек.

Своей приличной фотографии что-то не найду, а постить заимствованное из сети не хочется:(( Пусть будет ссылка на УФНовское поздравление к его 80-летию.

А я сегодня видел куницу!!!

Пересекла дорожку из левых зарослей в правые:))) Увы, сфотографировать не было ни малейших шансов, но хоть полюбовался, она офигительная!

А ежедневные сильные дожди, между тем, полностью размочили подъезды к речке, как бы не пропал весь июнь в этом смысле...
лошадь, диаграмма, Фейнман

Стерильные нейтрино

Sterile Neutrinos: https://arxiv.org/abs/2106.05913
Basudeb Dasgupta, Joachim Kopp
Neutrinos, being the only fermions in the Standard Model of Particle Physics that do not possess electromagnetic or color charges, have the unique opportunity to communicate with fermions outside the Standard Model through mass mixing. Such Standard Model-singlet fermions are generally referred to as "sterile neutrinos''. In this review article, we discuss the theoretical and experimental motivation for sterile neutrinos, as well as their phenomenological consequences. With the benefit of hindsight in 2020, we point out potentially viable and interesting ideas. We focus in particular on sterile neutrinos that are light enough to participate in neutrino oscillations, but we also comment on the benefits of introducing heavier sterile states. We discuss the phenomenology of eV-scale sterile neutrinos in terrestrial experiments and in cosmology, we survey the global data, and we highlight various intriguing anomalies. We also expose the severe tension that exists between different data sets and prevents a consistent interpretation of the global data in at least the simplest sterile neutrino models. We discuss non-minimal scenarios that may alleviate some of this tension. We briefly review the status of keV-scale sterile neutrinos as dark matter and the possibility of explaining the matter-antimatter asymmetry of the Universe through leptogenesis driven by yet heavier sterile neutrinos.
Comments: Submitted as an invited review for Physics Reports
лошадь, диаграмма, Фейнман

Причинность и гравитация

Causality and gravity: https://arxiv.org/abs/2106.05912
John F. Donoghue, Gabriel Menezes
We show how uncertainty in the causal structure of field theory is essentially inevitable when one includes quantum gravity. This includes the fact that lightcones are ill-defined in such a theory - independent of the UV completion of the theory. We include details of the causality uncertainty which arises in theories of quadratic gravity.
Comments: 15 pages, two figures
лошадь, диаграмма, Фейнман

Докопались до мышей: система диагностики пучка в эксперименте по ионизационному охлаждению мюонов

Performance of the MICE diagnostic system: https://arxiv.org/abs/2106.05813
The MICE collaboration
Muon beams of low emittance provide the basis for the intense, well-characterised neutrino beams of a neutrino factory and for multi-TeV lepton-antilepton collisions at a muon collider. The international Muon Ionization Cooling Experiment (MICE) has demonstrated the principle of ionization cooling, the technique by which it is proposed to reduce the phase-space volume occupied by the muon beam at such facilities. This paper documents the performance of the detectors used in MICE to measure the muon-beam parameters, and the physical properties of the liquid hydrogen energy absorber during running.
Comments: 27 pages, 18 figures
лошадь, диаграмма, Фейнман

Физика на пляже: почему галька не становится сферической

On the ocean beach -- why elliptic pebbles do not become spherical: https://arxiv.org/abs/2106.05835
Klaus Winzer, Gerhard C. Hegerfeldt
Among pebbles strewn across a sandy ocean beach one can find relatively many with a nearly perfect elliptical (ellipsoidal) shape, and one wonders how this shape was attained and whether, during abrasion, the pebbles would remain elliptical or eventually become spherical. Mainly the latter question was addressed in a previous publication which identified frictional sliding and rotation of an elliptic pebble as main abrasion processes in the surf waves. In particular, it was predicted that the ellipticity ϵ converges to a common equilibrium value for elliptic-like pebbles. Unfortunately, the derivation was based on an invalid force expression and a dimensionally unsuitable curvature. In this paper, not only force and curvature but also the contact duration with the sand surface during rotations is taken into account by fairly simple physical arguments, and it is shown that elliptic pebbles neither approach the same ellipticity and nor become more spherical nor more disk-like but rather that the ellipticity ϵ increases.
Comments: 12 pages, 8 figures, accepted for publication in EPJ Plus
лошадь, диаграмма, Фейнман

Лекции по сверхпроводимости и прочему

Стукнуло в голову сделать то, чего обычно не делаю, - пошерситить раздел Condensed Matter. Вот что нарыл:

Lecture Notes on Superconductivity: Condensed Matter and QCD: https://arxiv.org/abs/1810.11125
Roberto Casalbuoni
Lecture notes delivered in Barcellona in the fall of 2003

Introduction to superfluidity -- Field-theoretical approach and applications: https://arxiv.org/abs/1404.1284
Andreas Schmitt
In this pedagogical introduction, I discuss theoretical aspects of superfluidity and superconductivity, mostly using a field-theoretical formalism. While the emphasis is on general concepts and mechanisms behind superfluidity, I also discuss various applications in low-energy and high-energy physics. Besides some introductory and standard topics such as superfluid helium and superfluidity in a simple scalar field theory, the lecture notes also include more advanced chapters, for instance discussions of the covariant two-fluid formalism and Cooper pairing with mismatched Fermi surfaces.
Comments: 150 pages, v2: minor corrections, typos fixed, references added, version published in Lect. Notes Phys. 888, 1-155 (2014), ISBN 978-3-319-07946-2

Boson-Fermion Model of High-T_C Superconductivity ----A Progress Report: https://arxiv.org/abs/cond-mat/9811230
Hai-cang Ren
This is an invited lecture at the XXII International School of Theoretical Physics, Ustron, Poland, 9/10-9/15, 1998. The boson-fermion model of high T_C superconductivity is reviewed. Its applications to the pseudo-gap and DC transport coefficients are discussed.
Comments: 14 pages, 3 figures; A few changes in the quotations

Effective Gauge Theories, The Renormalization Group, and High-Temperature Superconductivity: https://arxiv.org/abs/cond-mat/9810324
A. Campbell-Smith, N.E. Mavromatos
These lectures serve as an introduction to the renormalization group approach to effective field theories, with emphasis on systems with a Fermi surface. For such systems, demanding appropriate scaling with respect to the renormalization group for the appropriate excitations leads directly to the important concept of quasiparticles and the connexion between large-N_f treatments and renormalization group running in theory space. In such treatments N_f denotes the number of effective fermionic degrees of freedom above the Fermi surface; this number is roughly proportional to the size of the Fermi surface. As an application of these ideas, non-trivial infra red structure in three dimensional U(1) gauge theory is discussed, along with applications to the normal phase physics of high-T_c superconductors, in an attempt to explain the experimentally observed deviations from Fermi liquid behaviour. Specifically, the direct current resistivity of the theory is computed at finite temperatures, T, and is found to acquire O(1/Nf) corrections to the linear T behaviour. Such scaling corrections are consistent with recent experimental observations in high T_c superconducting cuprates.
Comments: 38 pages LATEX, figures incorporated (incorrect citation ref. [3] corrected; no other changes)

Renormalization Group Methods: Landau-Fermi Liquid and BCS Superconductor: https://arxiv.org/abs/cond-mat/9508063
J. Froehlich, T. Chen, M. Seifert
This is the second part of the notes to the course on quantum theory of large systems of non-relativistic matter taught by J. Fröhlich at the 1994 Les Houches summer school. It is devoted to a sketchy exposition of some of the beautiful and important, recent results of J.Feldman and E.Trubowitz, and J. Feldman, H. Knörrer, D. Lehmann, J. Magnen, V. Rivasseau and E. Trubowitz. Their results are about a mathematical analysis of non-relativistic many-body theory, in particular of the Landau-Fermi liquid and BCS superconductivity, using Wilson's renormalization group methods and the techniques of the 1/N-expansion. While their work is ultimately aimed at a complete mathematical control (beyond perturbative expansions) of systems of weakly coupled electron gases at positive density and small or zero temperature, we can only illustrate some of their ideas within the context of perturbative solutions of Wilson-type renormalization group flow equations (we calculate leading-order terms in a 1/N-expansion, where N is an energy scale) and of one-loop effective potential calculations of the BCS superconducting ground state. Contents:
1. Background material
2. Weakly coupled electron gases
3. The renormalization group flow
4. Spontaneous breaking of gauge invariance, and superconductivity
Comments: 50 pages, Latex2e. Part II of lectures presented by J.F. at the 1994 Les Houches Summer School ``Fluctuating Geometries in Statistical Mechanics and Field Theory'' (also available at this http URL ). For part I, see cond-mat/9508062

Quantum Theory of Large Systems of Non-Relativistic Matter: https://arxiv.org/abs/cond-mat/9508062
J. Froehlich, U.M. Studer, E. Thiran
1. Introduction
2. The Pauli Equation and its Symmetries {2.1} Gauge-Invariant Form of the Pauli Equation {2.2} Aharonov-Bohm Effect {2.3} Aharonov-Casher Effect
3. Gauge Invariance in Non-Relativistic Quantum Many-Particle Systems {3.1} Differential Geometry of the Background {3.2} Systems of Spinning Particles Coupled to External Electromagnetic and Geometric Fields {3.3} Moving Coordinates and Quantum-Mechanical Larmor Theorem
4. Some Key Effects Related to the U(1)×SU(2) Gauge Invariance of Non-Relativistic Quantum Mechanics {4.1} ``Tidal'' Aharonov-Bohm and ``Geometric'' Aharonov-Casher Effects {4.2} Flux Quantization {4.3} Barnett and Einstein-deHaas Effects {4.4} Meissner-Ochsenfeld Effect and London Theory of Superconductivity {4.5} Quantum Hall Effect
5. Scaling Limit of the Effective Action of Fermi Systems, and Classification of States of Non-Relativistic Matter
6. Scaling Limit of the Effective Action of a Two-Dimensional, Incompressible Quantum Fluid {6.1} Scaling Limit of the Effective Action {6.2} Linear Response Theory and Current Sum Rules {6.3} Quasi-Particle Excitations and a Spin-Singlet Electron Pairing Mechanism
7. Anomaly Cancellation and Algebras of Chiral Edge Currents in Two- Dimensional, Incompressible Quantum Fluids {7.1} Integer Quantum Hall Effect and Edge Currents {7.2} Edge Excitations in Spin-Polarized Quantum Hall Fluids
8. Classification of Incompressible Quantum Hall Fluids {8.1} QH Fluids and QH Lattices: Basic Concepts {8.2} A Dictionary Between the Physics of QH Fluids and the Mathematics of QH Lattices {8.3} Basic Invariants of Chiral QH Lattices (CQHLs) and their Physical Interpretations {8.4} General Theorems and Classification Results for CQHLs {8.5} Maximally Symmetric CQHLs {8.6} Summary and Physical Implications of the Classification Results
Comments: 145 pages, Latex2e. Part I of lectures presented by J.F. at the 1994 Les Houches Summer School ``Fluctuating Geometries in Statistical Mechanics and Field Theory'' (also available at this http URL ). For part II, see cond-mat/9508063