Simplification of Flavour Combinatorics in the Evaluation of Hadronic Processes

A serious computational problem in the evaluation of hadronic collision processes is connected with the large number of partonic subprocesses included in the calculation. These are from the quark and gluon content of the initial hadrons, and from CKM quark mixing. For example, there are 180 subprocesses which contribute to the $W$+2jets process, and 292 subprocesses in $W$+3jets production at the LHC, even when quarks from only the first two generations are taken into account. We propose a simple modification of the rules for evaluation of cross sections and distributions, which avoids multiplication of channels from the mixture of quark states. The method is based on a unitary rotation of down quarks, thus, transporting the mixing matrix elements from vertices of Feynman diagrams to the parton distribution functions (PDF). As a result, one can calculate cross sections with significantly fewer subprocesses. For the example mentioned above, with the new rules, one need evaluate only 21 and 33 subprocesses respectively. The matrix elements of the subprocesses are calculated without quark mixing but with a modified PDF convolution which depends on the quark mixing angle, and on the topologies of gauge invariant classes of diagrams. The proposed method has been incorporated into the CompHEP program and checked with various examples.Comment: 10 pages (standard LaTeX code), 3 figures, 2 table

"Pair production of scalar top quarks in e+e- collisions at ILC."

We study the pair production of scalar top quarks in e+e- collisions with the subsequent decay of the top squarks into b-quarks and charginos. We simulate this process using PYTHIA6.4 for beam energies 2E_beam = 350, 400, 500, 800, 1000 GeV. Proposing a set of criteria we obtain a good separation of the signal stop events from top quark pair production which is the main background. The number of stop production events obtained with the proposed cuts for different energies is calculated for an integrated luminosity of 1000 1/fb. We propose a method to reconstruct the mass of the top squark, provided the mass of the lightest neutralino is known, and estimate the error of the mass determination for the case sqrt{s} = 500 GeV.Comment: 25 pages, 27 figures, ILC-NOTE-2008-042. v1 was presented by the 4-th author and published in the Proceedings of the 15-th International Seminar on High Energy Physics QUARKS-2008 (Institute for Nuclear Research of RAS, Sergiev Posad, Russia, 23-29 May 2008), V1, p.227-246, ISBN 978-5-94274-123-5. v2 - another set of cuts was chosen. v3 - some typos correcte

Development of the training - technological map of the scenario of the day form of the self-education of the educator

In the article the experience of development of the educational flow chart as forms of self-education of the tutor in the preschool educational organization is consideredВ статье рассматривается опыт разработки учебно-технологической карты как формы самообразования воспитателя в дошкольной образовательной организаци

CompHEP-PYTHIA interface: integrated package for the collision events generation based on exact matrix elements

CompHEP, as a partonic event generator, and PYTHIA, as a generator of final states of detectable objects, are interfaced. Thus, integrated tool is proposed for simulation of (almost) arbitrary collision processes at the level of detectable particles. Exact (multiparticle) matrix elements, convolution with structure functions, decays, partons hadronization and (optionally) parton shower evolution are basic stages of calculations. The PEVLIB library of event generators for LHC processes is described.Comment: Standard LaTeX, 4 pages. To appear in the proceedings of the Seventh International Workshop on Advanced Computing and Analysis Technics in Physics Research (ACAT2000, Fermilab, October 16-20, 2000

Postdocs in Russia: Peculiarities of Employment and Incentives

The article presents the results of the author’s research aimed at identifying the peculiarities of employment of postdocs, a relatively new labor category for the Russian academic labor market. Due to several difficulties associated with forming a sample of postdocs (difficulty in identifying key persons responsible for the development of postdoctoral programs; direct, but not always justified, refusals to provide data, difficulties in identifying potential respondents due to their occupation of various scientific positions in Russian universities), the “snowball” method was used. As a result, the empirical basis of the study was formed based on the results of an online survey of 44 postdocs. As part of the study, tasks related to compiling a socio-economic portrait of a postdoc based on economic, socio-demographic characteristics and indicators of research efficiency, identifying the characteristics of the employment and placement experience of postdocs, objective factors and individual motives for making decisions in the field of choosing postdoctoral programs were solved, as well as diagnostics of tools and channels for young researchers to search for vacancies. The authors distinguish between types of academic mobility (educational and labor) and consider postdoctoral studies as a promising form of external labor academic mobility aimed at attracting and retaining high-potential young researchers planning a long-term career in the academic labor market.Shifting the emphasis from the inbreeding model of university development (internal labor mobility) to the model of external labor academic mobility of young specialists allows those universities that can effectively manage the flow of academic human capital to receive additional socio-economic preferences and return on investment. There are very few similar empirical studies that analyze the features of the development of postdoctoral institutions in Russia and abroad and are based on quantitative and qualitative data from surveys of direct participants in external labor academic mobility – postdocs, which determines the scientific novelty and practical value of the proposed results