Suppression and enhancement of the critical current in multiterminal S/N/S mesoscopic structures

We analyse the measured critical current $I_{m\text{}}$ in a mesoscopic 4-terminal S/N/S structure. The current through the S/N interface is shown to consist not only of the Josephson component $I_{c}\sin \phi ,$ but also a phase-coherent part $I_{sg}\cos \phi$ of the subgap current. The current $I_{m}$ is determined by the both components $I_{c}$ and $I_{sg},$ and depends in a nonmonotonic way on the voltage $V$ between superconductors and normal reservoirs reaching a maximum at $V\cong \Delta /e$. The obtained theoretical resultas are in qualitative agreement with recent experimental data.Comment: 4 page, 3 figures. To be puplished in PRB Rapid co

The Ideal Mixing Departure in Vector Meson Physics

In this work we study the departure for the ideal $\phi-\omega$ mixing angle in the frame of the Nambu-Jona-Lasinio model. We have shown that in that context, the flavour symmetry breaking is unable to produce the shifting in the mixing angle. We introduce a nonet symmetry breaking in the neutral vector sector to regulate the non-strange content of the $\phi$ meson. The phenomenon is well reproduced by our proposal.Comment: 12 pages incl. 1 figur

Giant thermoemf in multiterminal superconductor/normal metal mesoscopic structures

We considered a mesoscopic superconductor/normal metal (S/N) structure in which the N reservoirs are maintained at different temperatures. It is shown that in the absence of current between the N reservoirs a voltage difference $V_{T}$ arises between the superconducting and normal conductors. The voltage $V_{T}$ oscillates with increasing phase difference $\phi$ between the superconductors, and its magnitude does not depend on the small parameter $(T/\epsilon_{F}).$Comment: Resubmited, some changes to Text and Figure

Flows of real gas in nozzles with unsteady local energy supply

When gas flows at a high speed in a channel with a variable cross sectional area and high-intensity energy supply, it experiences complicated physical and chemical processes producing high-temperature gas effects. High-temperature gas effects are a key issue related to design and optimization of nozzles of plasmatron of alternating current. The finite volume method is applied to solve unsteady compressible Euler equations with high-temperature gas effects. Solutions of some benchmark test cases are reported, and comparison between computational results of chemically equilibrium and perfect air flowfields is performed. The results of numerical simulation of one-dimensional and two-dimensional under- and over-expanded nozzle flows with a moving region of energy supply are presented. Output nozzle parameters are calculated as functions of a number and time of burning of plasmatron arcs. The results obtained show a qualitative pattern of gas dynamics and thermal processes in the nozzle with unsteady energy supply demonstrating the displacement of the nozzle shock wave towards the nozzle outlet in the over-expanded nozzle flow in comparison to perfect gas flow

Neon cryovacuum system for endurance tests of electrojet propulsion systems

In article Cryovacuum Oil-free system designed to operate in the pressure range (10⁵... 4·10⁻⁵) Pa is described. Pumps and cryopanels included in a vicious cycle of manufacture and storage of liquid neon. The vacuum system is designed IPENMA National Scientific Center KhIPT for endurance tests of electrojet propulsion systems (EPS). In work the cryovacuum system for EPS at which a working body are xenon or to a lesser extent, argon is presented. In work the cryovacuum system for EPS at which a working body are xenon or to a lesser extent, argon is presented. To explore new developments such engines especially for endurance tests (up to 1000 hours of continuous operation) necessary to create a clean oil-free vacuum (2·10⁻² Pa). It is provided with neon Cryovacuum systems that can remove the heat load of up to 10 W/cm². It is shown that at condensation more than 1.5 g/cm² of xenon don't occur changes in the speed of pumping of neon pumping-out elements, i.e. at the cryopanel area near 1m² carrying out resource tests of EPS is possible.Описана безмаслянная криовакуумная система, предназначенная для работы в диапазоне давлений (10⁵... 4·10⁻⁵) Па. Насосы и криопанели включены в замкнутый цикл получения и хранения жидкого неона. Вакуумная система разработана ИПЭНМУ ННЦ ХФТИ для проведения ресурсных испытаний электрореактивных двигательных установок (ЭРДУ). Представлена криовакуумная система для стационарных плазменых двигателей (СПД), у которых рабочим телом являются ксенон и, в меньшей степени, аргон. Для исследования новых разработок таких двигателей, в особенности для ресурсных испытаний, необходимо создание чистого безмаслянного вакуума (2·10⁻² Па), что обеспечивается неоновыми криовакуумными системами, которые могут снять тепловую нагрузку до 10 Ватт/см². Показано, что при конденсации ксенона более 1,5 г/см² не происходит изменения в скорости откачки неоновых откачивающих элементов, т.е. при площади криопанели около 1 м² возможно проведение ресурсных испытаний СПД.Описано безмасляну кріовакуумну систему, яка призначена для роботи в діапазоні тиску (10⁵... 4·10⁻⁵) Па. Помпи і кріопанелі включені до складу замкненого циклу отримання та зберігання рідинного неону. Вакуумну систему розроблено в ІПЕНМП ННЦ ХФТІ для проведення ресурсних випробувань електрореактивних двигунів (ЕРД). Представлено кріовакуумну систему для випробування стаціонарних плазмових двигунів (СПД), в яких робочою речовиною є ксенон або, в меншій мірі, аргон. Для дослідження нових розробок таких двигунів, особливо для проведення ресурсних випробувань, необхідне створення безмасляного вакууму (2·10⁻² Па), що забезпечується неоновими кріовакуумними системами, які можуть зняти теплове навантаження до 10 Ватт/см². Показано, що при конденсації ксенону більш 1,5 г/см² не робить змін у швидкості відкачування неонових відкачних елементів, тобто при площі кріопанелі 1 м² можливе проведення ресурсних випробувань СПД

Search for the radiative decay η→π0γγ\eta \to \pi^0 \gamma \gamma in the SND experiment at VEPP-2M

The $\eta \to \pi^0 \gamma \gamma$ decay was investigated by the SND detector at VEPP-2M $e^+e^-$ collider in the reaction $e^+e^-\to\phi\to \eta\gamma$. Here we present the results and some details of this study. We report an upper limit (90% c.l.) $Br(\eta \to \pi^0 \gamma \gamma)<8.4\times 10^{-4}$ as our final result. Our upper limit does not contradict the earlier measurement by GAMS spectrometer. To facilitate future studies a rather detailed review of the problem is also given.Comment: 24 pages, 6 figures, LaTex. To be published in Nucl. Phys.

Hairy black holes in theories with massive gravitons

This is a brief survey of the known black hole solutions in the theories of ghost-free bigravity and massive gravity. Various black holes exist in these theories, in particular those supporting a massive graviton hair. However, it seems that solutions which could be astrophysically relevant are the same as in General Relativity, or very close to them. Therefore, the no-hair conjecture essentially applies, and so it would be hard to detect the graviton mass by observing black holes.Comment: References added. 20 pages, 3 figures, based on the talk given at the 7-th Aegean Summer School "Beyond Einstein's theory of gravity", September 201

Topcolor-Assisted Supersymmetry

It has been known that the supersymmetric flavor changing neutral current problem can be avoided if the squarks take the following mass pattern, namely the first two generations with the same chirality are degenerate with masses around the weak scale, while the third generation is very heavy. We realize this scenario through the supersymmetric extension of a topcolor model with gauge mediated supersymmetry breaking.Comment: 12 pages, latex, no figure