A proof of the reggeized form of amplitudes with quark exchanges

A complete proof of the quark Reggeization hypothesis in the leading logarithmic approximation for any quark--gluon inelastic process in the multi--Regge kinematics in all orders of $\alpha_s$ is given. First, we show that the multi--Regge form of QCD amplitudes is guarantied if a set of conditions on the Reggeon vertices and the trajectories is fulfilled. Then, we examine these conditions and show that they are satisfied.Comment: 22 pages, 7 figures, use elsart.cl

Прогнозирование разрушения образцов композитных материалов под действием повторно-переменных нагружений

В статье представлены результаты экспериментального исследования полимерных композитных материалов при воздействии повторно - переменных нагружений. На основе экспериментальных данных получены параметры аналитической взаимосвязи силы повторно - переменных нагружений и соответствующей деформации образцов, а также дан прогноз их разрушения с учетом остаточной деформации

Differential equations and high-energy expansion of two--loop diagrams in D dimensions

New method of calculation of master integrals using differential equations and asymptotical expansion is presented. This method leads to the results exact in space-time dimension $D$ having the form of the convergent power series. As an application of this method, we calculate the two--loop master integral for "crossed--triangle" topology which was previously known only up to O(\ep) order. The case when a topology contains several master integrals is also considered. We present an algorithm of the term-by-term calculation of the asymptotical expansion in this case and analyze in detail the "crossed--box" topology with three master integrals.Comment: 13 pages,8 figures, uses elsart.cls. Misprints correcte

Origin of Multikinks in Dispersive Nonlinear Systems

We develop {\em the first analytical theory of multikinks} for strongly {\em dispersive nonlinear systems}, considering the examples of the weakly discrete sine-Gordon model and the generalized Frenkel-Kontorova model with a piecewise parabolic potential. We reveal that there are no $2\pi$-kinks for this model, but there exist {\em discrete sets} of $2\pi N$-kinks for all N>1. We also show their bifurcation structure in driven damped systems.Comment: 4 pages 5 figures. To appear in Phys Rev

Static-Electric-Field-Induced Polarization Effects in Harmonic Generation

Two static-electric-field-induced effects on harmonic generation are demonstrated analytically and numerically: elliptic dichroism (in which the harmonic yield is different for right and left elliptically polarized laser fields) and elliptical polarization of harmonics produced by linearly polarized driving laser fields. Both effects stem from interference of real and imaginary parts of the nonlinear atomic susceptibilities. Possibilities for experimentally measuring these effects are discussed

The limit load calculations for pipelines with axial complex-shaped defects

Based on the analytical model for the plastic limit state, a numerical procedure for estimating the remaining strength of a complex-shaped defect has been developed. Comparison of the calculation results obtained by the proposed procedure with the experimental data and the calculation results obtained by other methods showed its efficiency.С использованием аналитической модели пластического предельного состояния разра­ботана методика численного расчета оста­точной прочности объекта с дефектом слож­ной формы. Сравнение результатов расчета по предложенной методике с таковыми по другим методикам и экспериментальными данными свидетельствует о ее эффективнос­ти

Proof of the multi-Regge form of QCD amplitudes with gluon exchanges in the NLA

The multi--Regge form of QCD amplitudes with gluon exchanges is proved in the next-to-leading approximation. The proof is based on the bootstrap relations, which are required for the compatibility of this form with the s-channel unitarity. We show that the fulfillment of all these relations ensures the Reggeized form of energy dependent radiative corrections order by order in perturbation theory. Then we prove that all these relations are fulfilled if several bootstrap conditions on the Reggeon vertices and trajectory hold true. Now all these conditions are checked and proved to be satisfied.Comment: 15 page

Travelling solitons in the parametrically driven nonlinear Schroedinger equation

We show that the parametrically driven nonlinear Schroedinger equation has wide classes of travelling soliton solutions, some of which are stable. For small driving strengths nonpropogating and moving solitons co-exist while strongly forced solitons can only be stably when moving sufficiently fast.Comment: The paper is available as the JINR preprint E17-2000-147(Dubna, Russia) and the preprint of the Max-Planck Institute for the Complex Systems mpipks/0009011, Dresden, Germany. It was submitted to Physical Review

Statistical Model of Shape Moments with Active Contour Evolution for Shape Detection and Segmentation

This paper describes a novel method for shape representation and robust image segmentation. The proposed method combines two well known methodologies, namely, statistical shape models and active contours implemented in level set framework. The shape detection is achieved by maximizing a posterior function that consists of a prior shape probability model and image likelihood function conditioned on shapes. The statistical shape model is built as a result of a learning process based on nonparametric probability estimation in a PCA reduced feature space formed by the Legendre moments of training silhouette images. A greedy strategy is applied to optimize the proposed cost function by iteratively evolving an implicit active contour in the image space and subsequent constrained optimization of the evolved shape in the reduced shape feature space. Experimental results presented in the paper demonstrate that the proposed method, contrary to many other active contour segmentation methods, is highly resilient to severe random and structural noise that could be present in the data

Two-Loop Helicity Amplitudes for Quark-Quark Scattering in QCD and Gluino-Gluino Scattering in Supersymmetric Yang-Mills Theory

We present the two-loop QCD helicity amplitudes for quark-quark and quark-antiquark scattering. These amplitudes are relevant for next-to-next-to-leading order corrections to (polarized) jet production at hadron colliders. We give the results in the `t Hooft-Veltman and four-dimensional helicity (FDH) variants of dimensional regularization and present the scheme dependence of the results. We verify that the finite remainder, after subtracting the divergences using Catani's formula, are in agreement with previous results. We also provide the amplitudes for gluino-gluino scattering in pure N=1 supersymmetric Yang-Mills theory. We describe ambiguities in continuing the Dirac algebra to D dimensions, including ones which violate fermion helicity conservation. The finite remainders after subtracting the divergences using Catani's formula, which enter into physical quantities, are free of these ambiguities. We show that in the FDH scheme, for gluino-gluino scattering, the finite remainders satisfy the expected supersymmetry Ward identities.Comment: arXiv admin note: substantial text overlap with arXiv:hep-ph/030416