Generalized Calogero-Moser systems from rational Cherednik algebras

We consider ideals of polynomials vanishing on the W-orbits of the intersections of mirrors of a finite reflection group W. We determine all such ideals which are invariant under the action of the corresponding rational Cherednik algebra hence form submodules in the polynomial module. We show that a quantum integrable system can be defined for every such ideal for a real reflection group W. This leads to known and new integrable systems of Calogero-Moser type which we explicitly specify. In the case of classical Coxeter groups we also obtain generalized Calogero-Moser systems with added quadratic potential.Comment: 36 pages; the main change is an improvement of section 7 so that it now deals with an arbitrary complex reflection group; Selecta Math, 201

Quantum geometry of 3-dimensional lattices

We study geometric consistency relations between angles on 3-dimensional (3D) circular quadrilateral lattices -- lattices whose faces are planar quadrilaterals inscribable into a circle. We show that these relations generate canonical transformations of a remarkable ``ultra-local'' Poisson bracket algebra defined on discrete 2D surfaces consisting of circular quadrilaterals. Quantization of this structure leads to new solutions of the tetrahedron equation (the 3D analog of the Yang-Baxter equation). These solutions generate an infinite number of non-trivial solutions of the Yang-Baxter equation and also define integrable 3D models of statistical mechanics and quantum field theory. The latter can be thought of as describing quantum fluctuations of lattice geometry. The classical geometry of the 3D circular lattices arises as a stationary configuration giving the leading contribution to the partition function in the quasi-classical limit.Comment: 27 pages, 10 figures. Minor corrections, references adde

Collective and fractal properties of pion jets in the four-velocity space at intermediate energies

Experimental results are presented for study of collective and fractal properties of soft pion jets in the space of relative four-dimensional velocities. Significant decreasing is obtained for mean square of second particle distances from jet axis for pion-proton interactions at initial energies $\sim 3$ GeV in comparison with hadron-nuclear collisions at close energies. The decreasing results in power dependence of distance variable on collision energy for range $\sim 2 - 4$ GeV. The observation allows us to estimate the low boundary of manifestation of color degree of freedom in pion jet production. Cluster dimension values were deduced for pion jets in various reactions. Fractional values of this dimension indicate on the manifestation of fractal-like properties by pion jets. Changing of mean kinetic energy of jet particles and fractal dimension with initial energy increasing is consistent with suggestion for presence of color degrees of freedom in pion jet production at intermediate energies.Comment: The conference "Physics of fundamental interactions". ITEP, Moscow, Russia. November 23 - 27, 200

Global properties of magnetotail current sheet flapping: THEMIS perspectives

A sequence of magnetic field oscillations with an amplitude of up to 30 nT and a time scale of 30 min was detected by four of the five THEMIS spacecraft in the magnetotail plasma sheet. The probes P1 and P2 were at <I>X</I>=−15.2 and −12.7 <I>R<sub>E</sub></I> and P3 and P4 were at <I>X</I>=−7.9 <I>R<sub>E</sub></I>. All four probes were at −6.5><I>Y</I>>−7.5 <I>R<sub>E</sub></I> (major conjunction). Multi-point timing analysis of the magnetic field variations shows that fronts of the oscillations propagated flankward (dawnward and Earthward) nearly perpendicular to the direction of the magnetic maximum variation (<I>B</I><sub>1</sub>) at velocities of 20–30 km/s. These are typical characteristics of current sheet flapping motion. The observed anti-correlation between ∂<I>B</I><sub>1</sub>/∂<I>t</I> and the Z-component of the bulk velocity make it possible to estimate a flapping amplitude of 1 to 3 <I>R<sub>E</sub></I>. The cross-tail scale wave-length was found to be about 5 <I>R<sub>E</sub></I>. Thus the flapping waves are steep tail-aligned structures with a lengthwise scale of >10 <I>R<sub>E</sub></I>. The intermittent plasma motion with the cross-tail velocity component changing its sign, observed during flapping, indicates that the flapping waves were propagating through the ambient plasma. Simultaneous observations of the magnetic field variations by THEMIS ground-based magnetometers show that the flapping oscillations were observed during the growth phase of a substorm

Dynamics of turbulent jet with positive buoyancy in a stratified fluid

The modeling of flow induced by submerged sewer system was carried out within laborarory physical experiment. Results of experiments perfomed at two expeimental facilities (Large Termostratified Tank LTSB (20*4*2 m) and small ltank (1.2*0.5*0.5 m) with saline stratification) are presented. The theoretical model of Fan &Brooks (1969) was verified within the series of experiments in saline pycnocline–type stratification in wide range of parameters. The conditions of scaling modeling were determined on the basis of this model, and laboratory scale modeling with geometrical scale 1:27 was perfomed in LTSB. Excitation of intencive temperature oscillations in the picnocline was observed. They were interpreted as self-sustained oscillations of the buoayant plume

Оценка опасности выжимания порожних вагонов при маневровых соударениях и переходных режимах движения в тяжеловесных поездах

The increase in the transit and carrying capacity of cargo intensive sections and directions of railways is achieved by introducing into circulation of cargo trains of increased weight and length, which in turn leads to a change in longitudinal dynamics of movement and emergence of additional loads on rolling stock and the railway track.In this regard in relation to Russian conditions, to ensure the required volumes of transportation with a preset level of safety, it is necessary to revise the current standards designed for maximum longitudinal compression forces of 50 tf, which are currently more than doubled in heavy trains.Based on the analysis of existing regulatory documents, domestic and foreign experience, it was possible to substantiate the necessity to improve the longitudinal dynamics of trains and to propose some ways to achieve it. are proposed. The simulation of collision of a free running platform wagon with standard draft gears of Sh-1-TM type with a gondola cars’ cut also equipped with standard draft gears of Sh-1-TM type was carried out to identify accident modes. The study has allowed to conclude on the expediency of increasing the energy intensity of draft gear through new design solutions, as well as on reducing longitudinal forces through adoption of floating centre beams.Повышение пропускной и провозной способности грузонапряжённых участков и направлений железных дорог достигают путём введения в обращение грузовых поездов повышенного веса и длины, что в свою очередь приводит к изменению продольной динамики движения и возникновению дополнительных нагрузок на подвижной состав и железнодорожный путь.В этой связи применительно к российским условиям для обеспечения перевозок в необходимом объёме с заданным уровнем безопасности необходимо пересмотреть действующие нормативы, рассчитанные на максимальные продольные усилия сжатия 50 тс, которые в настоящее время в тяжеловесных поездах превышены более чем в два раза.На основе анализа существующих нормативных документов, отечественного и зарубежного опыта обоснована необходимость и предложены способы улучшения продольной динамики поездов. Проведено моделирование накатывания платформы с типовыми поглощающими аппаратами типа Ш-1-ТМ на сцеп полувагонов, также оснащённых типовыми поглощающими аппаратами типа Ш-1-ТМ, с определением аварийных режимов. Обоснована целесообразность повышения энергоёмкости поглощающих аппаратов за счёт новых конструктивных решений, а также снижения продольных усилий за счёт внедрения плавающих хребтовых балок

Coherent control of collective nuclear quantum states via transient magnons

Ultrafast and precise control of quantum systems at x-ray energies involves photons with oscillation periods below 1 as. Coherent dynamic control of quantum systems at these energies is one of the major challenges in hard x-ray quantum optics. Here, we demonstrate that the phase of a quantum system embedded in a solid can be coherently controlled via a quasi-particle with subattosecond accuracy. In particular, we tune the quantum phase of a collectively excited nuclear state via transient magnons with a precision of 1 zs and a timing stability below 50 ys. These small temporal shifts are monitored interferometrically via quantum beats between different hyperfine-split levels. The experiment demonstrates zeptosecond interferometry and shows that transient quasi-particles enable accurate control of quantum systems embedded in condensed matter environments

Atmospheric convection plays a key role in the climate of tidally-locked terrestrial exoplanets: insights from high-resolution simulations

This is the final version. Available from IOP Piblishing via the DOI in this recordUsing a 3D general circulation model (GCM), we investigate the sensitivity of the climate of tidallylocked Earth-like exoplanets, Trappist-1e and Proxima Centauri b, to the choice of a convection parameterization. Compared to a mass-flux convection parameterization, a simplified convection adjustment parameterization leads to a >60 % decrease of the cloud albedo, increasing the mean day-side temperature by ≈10 K. The representation of convection also affects the atmospheric conditions of the night side, via a change in planetary-scale wave patterns. As a result, using the convection adjustment scheme makes the night-side cold traps warmer by 17–36 K for the planets in our simulations. The day-night thermal contrast is sensitive to the representation of convection in 3D GCM simulations, so caution should be taken when interpreting emission phase curves. The choice of convection treatment, however, does not alter the simulated climate enough to result in a departure from habitable conditions, at least for the atmospheric composition and planetary parameters used in our study. The near-surface conditions both in the Trappist-1e and Proxima b cases remain temperate, allowing for an active water cycle. We further advance our analysis using high-resolution model experiments, in which atmospheric convection is simulated explicitly. Our results suggest that in a hypothetical global convection-permitting simulation the surface temperature contrast would be higher than in the coarse-resolution simulations with parameterized convection. In other words, models with parameterized convection may overestimate the inter-hemispheric heat redistribution efficiency.Leverhulme TrustScience and Technology Facilities Council (STFC

Steps Toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XV. Long-Term Optical Monitoring of NGC 5548

We present the results of three years of ground-based observations of the Seyfert 1 galaxy NGC 5548, which combined with previously reported data, yield optical continuum and broad-line H-beta light curves for a total of eight years. The light curves consist of over 800 points, with a typical spacing of a few days between observations. During this eight-year period, the nuclear continuum has varied by more than a factor of seven, and the H-beta emission line has varied by a factor of nearly six. The H-beta emission line responds to continuum variations with a time delay or lag of 10-20 days, the precise value varying somewhat from year to year. We find some indications that the lag varies with continuum flux in the sense that the lag is larger when the source is brighter.Comment: 29 pages, 6 figures. Accepted for publication in ApJ (1999 Jan 10