Volume 193, Nº 8 (2023)
Reviews of topical problems
Neutrino oscillations: status and prospects for the determination of neutrino mass ordering and the leptonic $CP$-violation phase
Resumo
This review is devoted to the 110th anniversary of the birth of Bruno Pontecorvo, an outstanding physicist who made an invaluable contribution to the development of modern neutrino physics, having predicted, inter alia, nonzero neutrino masses, mixing, and oscillations that were experimentally discovered in the early 2000s. Significant progress has been made over 20 years of experiments in determining the parameters of three-flavor neutrino oscillations. The status of and prospects for establishing neutrino mass ordering and the leptonic $CP$-violation phase $(\delta _{CP})$, unknown parameters of this theory, are discussed. It is expected that they will be measured in long-baseline experiments in the next decade. The ongoing accelerator experiments NOvA and T2K, which are currently the most sensitive to neutrino mass ordering and $\delta _{CP}$, are described in detail. For ease of comparison, NOvA and T2K techniques and results, including all aspects of data collection and analysis, are presented on a stage-by-stage basis. Possible reasons for the disagreement between the $\delta _{CP}$ values measured by NOvA and T2K are discussed. Future accelerator (DUNE and Hyper-Kamiokande) and reactor (JUNO) megaprojects are considered, along with experiments designed to use atmospheric neutrinos: IceCube Upgrade, KM3NeT (ORCA), and ICAL at INO, which can measure unknown oscillation parameters and refine the ones already determined.
Uspehi fizičeskih nauk. 2023;193(8):801-824
801-824
Mean-field concept and post-DMFT methods in the modern theory of correlated systems
Resumo
We briefly review methods for modeling correlated systems. The concept of correlations is of fundamental physical importance for systems such as Mott–Hubbard insulators, high-temperature superconductors, molecular magnets, and twisted bilayer graphene. With the Hubbard model chosen as a reference, we systematically describe various numerical methods, starting with the mean-field and related theories that map the physical system under study onto an effective interaction-free ensemble. We also discuss the dynamical mean-field theory (DMFT), which is one of the most common modern methods to describe local correlations exactly. DMFT-based diagram methods incorporate effects of nonlocal physics to varying degrees, with the local correlations taken into account in full. In addition, we describe the nondiagram fluctuating local field method, whereby fluctuations of the leading collective modes of the system can be treated nonperturbatively.
Uspehi fizičeskih nauk. 2023;193(8):825-844
825-844
Optical coherence tomography in elastography and angiography
Resumo
An overview of modalities that are new for biomedical diagnostics and that have emerged in recent years in optical coherence tomography (OCT)—optical coherence tomography angiography (OCTA) and optical coherence elastography (OCE)—is given. These modalities are extensions of OCT imaging technology, which is based on the principles of low-coherence interferometry and celebrated its 30th anniversary in 2021. The basic principles of OCTA and OCE are outlined, the appearance of which was largely stimulated by earlier similar functional extensions in medical ultrasound. A number of results are presented that illustrate previously inaccessible possibilities opened up by the new modalities for biomedical applications. The article is an extended version of the report presented at the Scientific Session of the Division of Physical Sciences of the Russian Academy of Sciences, held on December 13, 2021.
Uspehi fizičeskih nauk. 2023;193(8):845-871
845-871
Physics of our days
Uncertainties in comparing a human and an android robot
Resumo
It is shown that one of the significant results of human creativity in the 21st century has been the creation of android robots equipped with artificial intelligence. The level of perfection of these robots is becoming so high that it will soon be impossible to establish differences between them and living people by their external features and behavior. This leads to a logical fallacy: to equate humans and android robots, assuming that both have consciousness. Today, scientific research has expanded the understanding of the phenomenon of consciousness, but problems with its definition have not disappeared. The article provides evidence that the application of the term consciousness to android robots is a mistake that can lead to serious consequences.
Uspehi fizičeskih nauk. 2023;193(8):872-901
872-901
Methodological notes
On the role of phantom sources in the theory of superlenses
Resumo
The effect of the appearance of ‘phantom sources’ in a theoretical model of an image formed by an ideal Veselago lens has been investigated by transformation optics (TO) methods. It is shown that this effect cannot be used to explain the mechanism of superlensing. A method is proposed for eliminating phantom sources in the construction of image models by TO methods. An expression is given for the electromagnetic field which forms an ideal image of a point radiation source when its distance from the front surface of the lens is equal to its thickness. An explanation is given as to why a rigorous model of the ideal image of a dipole source cannot be constructed if the distance between the source and the lens is shorter than its thickness.
Uspehi fizičeskih nauk. 2023;193(8):902-908
902-908
Personalia
Yuri Tsolakovich Oganessian (on his 90th birthday)
Uspehi fizičeskih nauk. 2023;193(8):909-910
909-910
Bibliography
New books on physics and related sciences: August 2023
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911-911
Physics news on the Internet: August 2023
Uspehi fizičeskih nauk. 2023;193(8):912-912
912-912