W + 2 jets production at Tevatron: VECBOS and CompHEP comparison

Results of calculation of all subprocesses in proton-antiproton collisions which contribute to the W+2jets final state are presented at Tevatron energy. The calculation has been carried out by means of the CompHEP software package. A detail comparison with VECBOS generator results for cross sections and various distributions shows an agreement at the level of Monte-Carlo accuracy. Therefore the independent check of VECBOS generator has been done. In addition to the VECBOS generator a new generator based on CompHEP allows to study individual subprocesses like Wb\bar{b} or Wc\bar{c}. The last point is important, for instance, for study Wb\bar{b} part of the background for single top or Standard Model Higgs signal at Tevatron

Spin-flop transition in uniaxial antiferromagnets: magnetic phases, reorientation effects, multidomain states

The classical spin-flop is the field-driven first-order reorientation transition in easy-axis antiferromagnets. A comprehensive phenomenological theory of easy-axis antiferromagnets displaying spin-flops is developed. It is shown how the hierarchy of magnetic coupling strengths in these antiferromagnets causes a strongly pronounced two-scale character in their magnetic phase structure. In contrast to the major part of the magnetic phase diagram, these antiferromagnets near the spin-flop region are described by an effective model akin to uniaxial ferromagnets. For a consistent theoretical description both higher-order anisotropy contributions and dipolar stray-fields have to be taken into account near the spin-flop. In particular, thermodynamically stable multidomain states exist in the spin-flop region, owing to the phase coexistence at this first-order transition. For this region, equilibrium spin-configurations and parameters of the multidomain states are derived as functions of the external magnetic field. The components of the magnetic susceptibility tensor are calculated for homogeneous and multidomain states in the vicinity of the spin-flop. The remarkable anomalies in these measurable quantities provide an efficient method to investigate magnetic states and to determine materials parameters in bulk and confined antiferromagnets, as well as in nanoscale synthetic antiferromagnets. The method is demonstrated for experimental data on the magnetic properties near the spin-flop region in the orthorhombic layered antiferromagnet (C_2H_5NH_3)_2CuCl_4.Comment: (15 pages, 12 figures; 2nd version: improved notation and figures, correction of various typos

CompHEP 4.4 - Automatic Computations from Lagrangians to Events

We present a new version of the CompHEP program (version 4.4). We describe shortly new issues implemented in this version, namely, simplification of quark flavor combinatorics for the evaluation of hadronic processes, Les Houches Accord based CompHEP-PYTHIA interface, processing the color configurations of events, implementation of MSSM, symbolical and numerical batch modes, etc. We discuss how the CompHEP program is used for preparing event generators for various physical processes. We mention a few concrete physics examples for CompHEP based generators prepared for the LHC and Tevatron.Comment: The paper has been presented on IX International Workshop on Advanced Computing and Analysis Techniques in Physics Research December 1-5, 2003. KEK, Japan. 10 pages, 2 figure

Language as a special tool for intercultural understanding

Наш мир растёт и развивается, и мы не можем остановить этот процесс. Современность готовит человеку всё новые и новые вызовы и испытания. Главная задача человечества заключается в том, чтобы сохранить свой высококультурный облик, преумножить нравственные ценности и передать их будущим поколениям. Родной язык является неотъемлемой частью каждой национальной культуры. Без языка культура становится безликой, бессмысленной и статичной. Язык, как главный источник её прогресса и распространения, подвергается сильнейшим внешним влияниям. Языковое своеобразие каждого народа не может находиться в изоляции от остального мира, как не может существовать культура вне контекста своих исторических условий. Сохранению национальных культур и языков способствует воспитание толерантности и терпимости в современном обществе. Добиться грамотного диалога культур можно лишь упорным трудом и заинтересованностью всех сторон в достижении взаимопонимания и нахождении мирного компромисса. Именно на взаимопонимании и диалоге культур должны строиться современные международные дипломатические отношения. Возрождение принципов гуманизма и добра – первый шаг на пути к установлению мира между крупнейшими державами. Человечеству несравнимо легче развиваться в гармоничных условиях, потому понимание и принятие чужого языка и культуры является для нас главным условием плодотворного сотрудничества.Our world keeps developing and growing, and we cannot prevent this process. The present is preparing new and new challenges and difficulties for us. The main task for humanity is to preserve its high cultured make-up; to increase moral, spiritual values and past them to future generations. Native language is an integral part of every ethnic culture. Culture becomes featureless, unmeaning and static without language. Language, as the main source of its progress and spreading, undergoes powerful external impacts. Language identity of every nation cannot be in isolation from the other world; as well as culture cannot exist out of its historical conditions context. Education of tolerance and indulgence in modern society makes for preservation of ethnic cultures and languages. The only possible opportunity to obtain a skilful cultural dialogue for parties is to work hard and be interested in achieving of understanding and peace compromise. Contemporary international diplomatic relations should be based on cultural dialogue and understanding. Revival of humanistic principles is the first step to establishment the peace between world powers. Humanity is developing incomparably easier in harmonic conditions. That is why, understanding and acceptance of foreign languages and cultures is the main term of fruitful collaboration

Analytical solution of second Stokes problem of behaviour of rarefied gas with Cercignani boundary accomodation conditions

Analytical solution of second Stokes problem of behaviour of rarefied gas with Cercignani boundary accomodation conditions The second Stokes problem about behaviour of rarefied gas filling half-space is analytically solved. A plane, limiting half-space, makes harmonious fluctuations in the plane. The kinetic BGK-equation (Bhatnagar, Gross, Krook) is used. The boundary accomodation conditions of Cercignani of reflexion gaseous molecules from a wall are considered. Distribution function of the gaseous molecules is constructed. The velocity of gas in half-space is found, also its value direct at a wall is found. The force resistance operating from gas on border is found. Besides, the capacity of dissipation of the energy falling to unit of area of the fluctuating plate limiting gas is obtained.Comment: 26 pages, 5 figure

The Second Stokes Problem with Specular - Diffusive Boundary Conditions in Kinetic Theory

The second Stokes problem with specular - diffusive boundary conditions of the kinetic theory is considered. The new method of the decision of the boundary problems of the kinetic theory is applied. The method allows to receive the decision with any degree of accuracy. At the basis of a method lays the idea of representation of a boundary condition on distribution function in the form of a source in the kinetic equation. By means of integrals Fourier the kinetic equation with a source is reduced to the integral equation of Fredholm type of the second kind. The decision is received in the form of Neumann's series.Comment: 20 pages, 2 figure

Magnetoresistive study of antiferromagnetic--weak ferromagnetic transition in single-crystal La2_{2}CuO4+δ_{4+\delta}

The resistive measurements were made to study the magnetic field-induced antiferromagnetic (AF) - weak ferromagnetic (WF) transition in La$_2$CuO$_4$ single-crystal. The magnetic field (DC or pulsed) was applied normally to the CuO$_2$ layers. The transition manifested itself in a drastic decrease of the resistance in critical fields of ~5-7 T. The study is the first to display the effect of the AF -WF transition on the conductivity of the La$_2$CuO$_4$ single-crystal in the parallel - to - CuO$_2$ layers direction. The results provide support for the 3-dimensional nature of the hopping conduction of this layered oxide.Comment: 8 pages, 7 figures, RevTe