On Modifications of the Sp(2) Covariant Superfield Quantization

We propose a modification of the Sp(2) covariant superfield quantization to realize a superalgebra of generating operators isomorphic to the massless limit of the corresponding superalgebra of the osp(1,2) covariant formalism. The modified scheme ensures the compatibility of the superalgebra of generating operators with extended BRST symmetry without imposing restrictions eliminating superfield components from the quantum action. The formalism coincides with the Sp(2) covariant superfield scheme and with the massless limit of the osp(1,2) covariant quantization in particular cases of gauge-fixing and solutions of the quantum master equations.Comment: 11 pages, to be published in Phys. Lett.

Physical unitarity in the Lagrangian Sp(2)-symmetric formalism

The structure of state vector space for a general (non-anomalous) gauge theory is studied within the Lagrangian version of the $Sp(2)$-symmetric quantization method. The physical {\it S}-matrix unitarity conditions are formulated. The general results are illustrated on the basis of simple gauge theory models.Comment: 26 pages, LaTE

One-loop effective action for Einstein gravity in special background gauge

The one-loop effective action for Einstein gravity in a special one-parameter background gauge is calculated up to first order in a gauge parameter. It is shown that the effective action does not depend upon the gauge parameter on shell.Comment: 17 pages, Latex, no figure

Magnetotransport study of the charged stripes in high-T_c cuprates

We present a study of the in-plane and out-of-plane magnetoresistance (MR) in heavily-underdoped, antiferromagnetic YBa_{2}Cu_{3}O_{6+x}, which reveals a variety of striking features. The in-plane MR demonstrates a "d-wave"-like anisotropy upon rotating the magnetic field H within the ab plane. With decreasing temperature below 20-25 K, the system acquires memory: exposing a crystal to the magnetic field results in a persistent in-plane resistivity anisotropy. The overall features can be explained by assuming that the CuO_2 planes contain a developed array of stripes accommodating the doped holes, and that the MR is associated with the field-induced topological ordering of the stripes.Comment: 4 pages, 5 figures, invited paper at M2S-HTSC-VI, to be published in Physics C (Proceedings of the International Conference on Materials and Mechanisms of Superconductivity, High Temperature Superconductors VI (M2S-HTSC-VI), Houston, Feb 20-25, 2000

Gauge (in)dependence and background field formalism

It is shown that the gauge invariance and gauge dependence properties of effective action for Yang-Mills theories should be considered as two independent issues in the background field formalism. Application of this formalism to formulate the functional renormalization group approach is discussed. It is proven that there is a possibility to construct the corresponding average effective action invariant under the gauge transformations of background vector field. Nevertheless, being gauge invariant this action remains gauge dependent on-shell.Comment: 14 pages, v2: typos corrected, v3:minor correction in Eqs. (2.24), v4: a reference added, misprints corrected, accepted for publication in PL

The Future of European Cooperation: A View from Moscow

A discussion on a wide range of topics concerned with Pan-European cooperation including military and security issues, aspects related to socio-economic and human rights, and Russian relations with European countries and institutions, as well as the role of the United Nations, its institutions and specialized agencies in fostering multilateral cooperation. Also included is the text in Russian.Russia, Foreign Policy, International Affairs