4,313 research outputs found
Universal Torsion-Induced Interaction from Large Extra Dimensions
We consider the Kaluza-Klein (KK) scenario in which only gravity exists in
the bulk. Without the assumption of symmetric connection, the presence of brane
fermions induces torsion. The result is a universal axial contact interaction
that dominates those induced by KK gravitons. This enhancement arises from a
large spin density on the brane. Using a global fit to Z-pole observables, we
find the 3 sigma bound on the scale of quantum gravity to be 28 TeV for n=2. If
Dirac or light sterile neutrinos are present, the data from SN1987A increase
the bound to \sqrt{n}M_S >= 210 TeV.Comment: 9 pages REVTeX, 1 postscript figure, uses axodraw.st
Charge localization at the interface between La1-xSrxMnO3 and the infinite layers cuprate CaCuO2
(CaCuO2)m/(La0.7Sr0.3MnO3)n superlattices, consisting of the infinite layers
cuprate CaCuO2 and the optimally doped manganite La1-xSrxMnO3, were grown by
pulsed laser deposition. The transport properties are dominated by the
manganite block. X-Ray Absorption spectroscopy measurements show a clear
evidence of an orbital reconstruction at the interface, ascribed to the
hybridization between the Cu 3d3z2-r2 and the Mn 3d3z2-r2 orbitals via
interface apical oxygen ions. Such a mechanism localizes holes at the
interfaces, thus preventing charge transfer to the CaCuO2 block. Some charge
(holes) transfer occurs toward the La0.7Sr0.3MnO3 block in strongly oxidized
superlattices, contributing to the suppression of the magnetotransport
properties.Comment: 20 pages, 6 figure
On the Quantum Inverse Problem for the Closed Toda Chain
We reconstruct the canonical operators of the quantum closed Toda
chain in terms of Sklyanin's separated variables.Comment: 16 page
Специализация и концентрация работников малых и средних предприятий: российские данные
Goal of study is to assess the current level of industry concentration and regional specialization small and medium enterprises in Russia using Krugman indices. The study uses official statistics for 2016, describing the number of enterprises employees located in 80 regions and specializing in 13 types of economic activity. In this research they determine the indices values of enterprises industry concentration and regional specialization. Authors also carry out comparative analysis of changes in the values of these indices for the period from 2010 to 2016. They also establish the patterns characteristic of industry concentration and regional specialization.Целью исследования является оценка текущего уровня отраслевой концентрации и региональной специализации малых и средних предприятий России с использованием индексов Кругмана. В исследовании используется официальная статистика за 2016 год, описывающая численность работников предприятий, расположенных в 80 регионах и специализирующихся на 13 видах экономической деятельности. В данном исследовании определены значения индексов отраслевой концентрации и региональной специализации. Приводится сравнительный анализ изменений значений этих показателей за период с 2010 по 2016 год. Установлены закономерности, характерные для концентрации производства малых и средних предприятий и их территориальной специализации
A-site Ordering versus Electronic Inhomogeneity in CMR-Manganite Films
Epitaxial La3/4Ca1/4MnO3/MgO(100) (LCMO) thin films show unusual rhombohedral
(R-3c) structure with a new perovskite superstructure due to unique ordering of
La and Ca at the A-site positions. Very sharp insulator-metal and
para-ferromagnetic phase transitions at temperatures up to TMI ~ TC=295 K were
observed. The ordered films were electronically homogeneous down to 1 nm scale
as revealed by scanning tunnelling microscopy/spectroscopy. In contrast,
orthorhombic and A-site disordered LCMO demonstrate broadened phase transitions
as well as mesoscopic phase separation for T<<TC. The unique La/Ca ordering
suppresses cation mismatch stress within one super-cell, a~1.55 nm, enhancing
electronic homogeneity. Phase separation scenario seems not to be a unique
mechanism for CMR as very large CMR=500 % was also observed in A-site ordered
films.Comment: We have added two references and additional sentence
Searching singlet extensions of the supersymmetric standard model in orbifold compactification of heterotic string
We search for supersymmetric standard model realizations with extra singlets
and extra using the heterotic string compactification on the orbifold with two Wilson lines. We analyze the vacuum restabilization
mechanism for three representative Pati-Salam string models obtained in the
literature and present detailed results for the effective superpotential
compatible with the string selection rules. An automated selection of
semi-realistic vacua along flat directions in the non-Abelian singlet modes
field space is performed by requiring the presence of massless pairs of
electroweak Higgs bosons having trilinear superpotential couplings with
massless singlet modes and the decoupling of color triplet exotic modes needed
to suppress and number violating processes.Comment: revtex4 format, 21 pages, 7 tables, shortened version added
reference
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