On amplitudes in self-dual sector of Yang-Mills theory

Self-dual perturbiner in the Yang-Mills theory is constructed by the twistor methods both in topologically trivial and topologically nontrivial cases. Maximally helicity violating amplitudes and their instanton induced analogies are briefly discussed.Comment: 9 pages, Latex, a misguided reference is corrected, ps is also available at http://wwwtheor.itep.ru/preprints/1996

On noncommutative vacua and noncommutative solitons

We consider noncommutative theory of a compact scalar field. The recently discovered projector solitons are interpreted as classical vacua in the model considered. Localized solutions to the projector equation are pointed out and their brane interpretation is discussed. An example of the noncommutative soliton interpolating between such vacua is given. No strong noncommutativity limit is assumed.Comment: 9 pages, latex, references adde

On Infrared Universality in Massive Theories. Another Example

The infrared behaviour of the ${\phi}^3$-theory is discussed stressing analogies with the Witten-Seiberg story about $N=2$ $QCD$. Though the microscopic theory is apparently not integrable, the effective theory is shown to be integrable at classical level, and a general solution of it in terms of hypergeometric functions is obtained. An effective theory for the multiparticle soft scattering is sketched.Comment: 9 pages, Latex, ps is available at http://venus.itep.ru/preprints/1996/96016.ps.g

Schwinger type processes via branes and their gravity duals

We consider Schwinger type processes involving the creation of the charge and monopole pairs in the external fields and propose interpretation of these processes via corresponding brane configurations in Type IIB string theory. We suggest simple description of some new interesting nonperturbative processes like monopole/dyon transitions in the electric field and W-boson decay in the magnetic field using the brane language. Nonperturbative pair production in the strong coupling regime using the AdS/CFT correspondence is studied. The treatment of the similar processes in the noncommutative theories when noncommutativity is traded for the background fields is presented and the possible role of the critical magnetic field which is S-dual to the critical electric field is discussed.Comment: 29pp, LaTeX; v3. reference adde

Phase Transitions in Higher Derivative Gravity

This paper deals with black holes, bubbles and orbifolds in Gauss-Bonnet theory in five dimensional anti de Sitter space. In particular, we study stable, unstable and metastable phases of black holes from thermodynamical perspective. By comparing bubble and orbifold geometries, we analyse associated instabilities. Assuming AdS/CFT correspondence, we discuss the effects of this higher derivative bulk coupling on a specific matrix model near the critical points of the boundary gauge theory at finite temperature. Finally, we propose another phenomenological model on the boundary which mimics various phases of the bulk space-time.Comment: 33 pages, 12 figures, LaTeX, typos corrected, clarifications in sections 5 and 6, references adde

One-loop corrections to the metastable vacuum decay

We evaluate the one-loop prefactor in the false vacuum decay rate in a theory of a self interacting scalar field in 3+1 dimensions. We use a numerical method, established some time ago, which is based on a well-known theorem on functional determinants. The proper handling of zero modes and of renormalization is discussed. The numerical results in particular show that quantum corrections become smaller away from the thin-wall case. In the thin-wall limit the numerical results are found to join into those obtained by a gradient expansion.Comment: 31 pages, 7 figure

Geometry and physics on w_#infinity# orbits

Available from TIB Hannover: RN5063(93-06) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Integrable theories and nonlinear conformal transformations

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Integrable theories and nonlinear conformal transformations

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On a multiorbit geometrical action for the integrable systems

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