Measurement of event shape distributions and moments in e+e- -> hadrons at 91-209 GeV and a determination of alpha_s

We have studied hadronic events from e+e- annihilation data at centre-of-mass energies from 91 to 209 GeV. We present distributions of event shape observables and their moments at each energy and compare with QCD Monte Carlo models. From the event shape distributions we extract the strong coupling alpha_s and test its evolution with energy scale. The results are consistent with the running of alpha_s expected from QCD. Combining all data, the value of alpha_s(M_Z) is determined to be alpha_s(M_Z) = 0.1191 +- 0.0005 (stat.) +- 0.0010 (expt.) +- 0.0011 (hadr.) +- 0.0044 (theo.). The energy evolution of the moments is also used to determine a value of alpha_s with slightly larger errors: alpha_s(M_Z) = 0.1223 +- 0.0005 (stat.) +- 0.0014 (expt.) +- 0.0016 (hadr.) +0.0054 -0.0036 (theo.).Comment: 63 pages 26 fi

Searches for Gauge-Mediated Supersymmetry Breaking Topologies in e+e- collisions at LEP2

In gauge-mediated supersymmetry (SUSY) breaking (GMSB) models the lightest supersymmetric particle (LSP) is the gravitino and the phenomenology is driven by the nature of the next-to-lightest SUSY particle (NLSP) which is either the lightest neutralino, the stau or mass degenerate sleptons. Since the NLSP decay length is effectively unconstrained, searches for all possible lifetime and NLSP topologies predicted by GMSB models in e+e- collisions are performed on the data sample collected by OPAL at centre-of-mass energies up to 209 GeV at LEP. Results independent of the NLSP lifetime are presented for all relevant final states including direct NLSP pair-production and, for the first time, also NLSP production via cascade decays of heavier SUSY particles. None of the searches shows evidence for SUSY particle production. Cross-section limits are presented at the 95% confidence level both for direct NLSP production and for cascade decays, providing the most general, almost model independent results. These results are then interpreted in the framework of the minimal GMSB (mGMSB) model, where large areas of the accessible parameter space are excluded. In the mGMSB model, the NLSP masses are constrained to be larger than 53.5 GeV/c^2, 87.4 GeV/c^2 and 91.9 GeV/c^2 in the neutralino, stau and slepton co-NLSP scenarios, respectively. A complete scan on the parameters of the mGMSB model is performed, constraining the universal SUSY mass scale Lambda from the direct SUSY particle searches: Lambda > 40, 27, 21, 17, 15 TeV/c^2 for messenger indices N=1, 2, 3, 4, 5 respectively, for all NLSP lifetimes.Comment: 4 pages, 2 figures. To appear in Proceedings of SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine, California, 12-17 June 200

Flavour Independent hA Search and Two Higgs Doublet Model Interpretation of Neutral Higgs Boson Searches at LEP

Upper limits on the cross-section of the pair-production process e+e- -> h0A0 assuming 100% decays into hadrons, are derived from a new search for the h0A0 -> hadrons topology, independent of the hadronic flavour of the decay products. Searches for the neutral Higgs bosons h0 and A0, are used to obtain constraints on the Type II Two Higgs Doublet Model (2HDM(11)) with no CP violation in the Higgs sector and no additional non Standard Model particles besides the five Higgs bosons. The analysis combines LEP1 and LEP2 data collected with the OPAL detctor up to the highest available centre-of-mass energies. The searches are sensitive to the h0, A0 -> qq, gg,tau+tau- and h0 -> A0A0 decay modes of the Higgs bosons. The 2HDM(II) parameter space is explored in a detailed scan. Large regions of the 2HDM(II) parameter space are excluded at the 95% CL in the (mh, mA), (mh, tanb) and (mA, tanb) planes, using both direct neutral Higgs boson searches and indirect limits derived from Standard Model high precision measurements. The region 1 lesssim mh lesssim 55 GeV and 3 lesssim mA lesssim 63 GeV is excluded at 95% CL independently of the choice of the 2HDM(II) parameters.Comment: 37 pages, 11 figures, Submitted to Eur. Phys. J.

Стартап выведения на внутриигровой рынок IT-продукта на базе платформы Steam

Анализ способов ведения коммерческой деятельности в рамках платформы Steam и игры Counter-Strike: Global Offensive. Разработка it-продукта для повышения эффективности работы на платформе Steam. Оформление разработки в качестве стартапа.Analysis of ways of doing business within the Steam platform and the game Counter-Strike: Global Offensive. Development of an it-product to improve the efficiency of work on the Steam platform. Registration of development as a startup

Оценка воздействия социальных медиа на политические и социокультурные взгляды молодежи в условиях глобальной трансформации общества (на примере видеоблогинга)

Исследование социальных медиа - одна из самых динамично развивающихся областей современной социологии. Актуальность исследования обусловлена трансформацией общественных ценностей, формированием глобальной политической и культурной среды и значительным влиянием современных информационных технологий на всю социокультурную систему. Целью исследования является оценка воздействия социальных медиа на социокультурную трансформацию общества и анализ влияния видеоблогинга как формы социальных медиа на молодых людей в возрасте от 17 до 30 лет. Методы. В процессе исследования был использован абстрактно-логический подход на основе системного анализа существующих эмпирических данных и онлайн-опроса, проведенного в социальной сети «ВКонтакте» среди студентов МГУ им. М.В. Ломоносова и студентов Национального исследовательского университета «Высшая школа экономики». Опрос содержал большое количество вариантов ответов (перечисление имен известных блогеров) и возможность добавления респондентом собственных вариантов ответов и комментариев. Результаты. Выяснилось, что воздействие блогеров на мировоззрение зрителей молодого поколения значительно. Половина опрошенных респондентов в возрасте от 17 до 30 лет интересуются политическими блогами, что говорит о возрастающей роли видеоблогинга среди молодежи в сети Интернет. Этот вид социальных медиа становится ареной политической борьбы за влияние на мировоззрение молодежи. Большинство участников опроса уделяют внимание политизированным блогерам, в частности Алексею Навальному. Значительная часть респондентов также следит за научно-популярными блогами, что может говорить о желании получать новые знания в сжатом и упрощенном виде.The study of social media is one of the most dynamically developing areas of modern sociology. The relevance of the study is caused by transformation of social values, emergence of global political and cultural environment, and significant impact of modern information technologies on the entire socio-cultural system. The aim of the study is to assess the impact of social media on the socio-cultural transformation of society and to analyze the impact of video blogging as a form of social media on young people aged 17 to 30 years. The method. The abstract-logical approach based on the system analysis of existing empirical data and an online-survey was used. The survey was conducted in the social network Vkontakte among students of the Lomonosov Moscow State University and National Research University «Higher School of Economics». The survey had a large number of answers and the possibility for respondents to add their own answers and comments. Results. It was found that the impact of bloggers on the worldview of the younger generation is significant. Half of the respondents aged 17 to 30 are interested in political blogs, which indicates the increasing role of video blogging among young people on the internet. This type of social media becomes battleground for political struggle for influence on the worldview of young people. The majority of respondents pay attention to politicized bloggers, in particular Alexei Navalny. A significant part of respondents also follows popular science blogs, which may indicate a desire to gain new knowledge in a concise and simplified form

Electroweak measurements in electron–positron collisions at w-boson-pair energies at lep

Contains fulltext : 121524.pdf (preprint version ) (Open Access

Search for anomalous production of dilepton events with missing transverse momentum in e+ e- collisions at s**(1/2) = 183-Gev to 209-GeV

In total 1317 di-lepton events with significant missing transverse momentum were identified in a total data sample of 680 pb-1 collected at e+e- centre-of-mass energies ranging from 183 GeV to 209 GeV. The number of di-lepton events, the dependence on centre-of-mass energy, and the event properties are consistent with expectations from Standard Model processes, predominantly W+W- production with both W bosons decaying leptonically. This topology is also an experimental signature for the pair production of new particles that decay to a charged lepton accompanied by one or more invisible particles. No evidence for new phenomena is apparent. Upper limits are presented on the production cross-section multiplied by the relevant branching ratio squared for sleptons, leptonically decaying charginos and charged Higgs bosons. Mass limits are also given.Comment: 42 pages, 15 figures, Submitted to Eur. Phys. J.

Study of Z pair production and anomalous couplings in e+ e- collisions at s**(1/2) between 190-GeV and 209-GeV

A study of Z-boson pair production in e+e- annihilation at center-of-mass energies between 190 GeV and 209 GeV is reported. Final states containing only leptons, (l+l-l+l- and l+l-nn), quark and lepton pairs, (qql+l-, qqnn) and only hadrons (qqqq) are considered. In all states with at least one Z boson decaying hadronically, lifetime, lepton and event-shape tags are used to separate bb pairs from qq final state. Limits on anomalous ZZgamma and ZZZ couplings are derived from the measured cross sections and from event kinematics using an optimal observable method. Limits on low scale gravity with large dimensions are derived from the cross sections and their dependence on polar angle.Comment: 34 pages, 10 figures, Submitted to Eur. Phys.

Study of Bose-Einstein correlations in e+e- -> W+W- events at LEP

Bose-Einstein correlations between like-sign charged-particle pairs in e(+)e(-) --> W+ W- events recorded with the OPAL detector at LEP at centre-of-mass energies between 183 GeV and 209 GeV are studied. Recently proposed methods which allow direct searches for correlations in the data via distributions of test variables are used to investigate the presence of correlations between hadrons originating from different W bosons in W+W- --> q (q) over barq (q) over bar events. Within the statistics of the data sample no evidence for inter - WW Bose-Einstein correlations is obtained. The data are also compared with predictions of a recent implementation of Bose-Einstein correlation effects in the Monte Carlo model PYTHIA

Constraints on anomalous quartic gauge boson couplings from vv vˉ\bar{v} γ\gamma γ\gamma and qq qˉ\bar{q} gamma gamma events at LEP-2

Anomalous quartic couplings between the electroweak gauge bosons may contribute to the vv gamma gamma and qq gamma gamma final states produced in e+e- collisions. This analysis uses the LEP2 OPAL data sample at centre-of-mass energies up to 209 GeV. Event selections identify vv gamma gamma and qq gamma gamma events in which the two photons are reconstructed within the detector acceptance. The cross-section for the process e+e- -> qq gamma gamma is measured. Averaging over all energies, the ratio of the observed e+e- -> qq gamma gamma cross-section to the Standard Model expectation is R(data/SM) = 0.92 +- 0.07 +- 0.04 where the errors represent the statistical and systematic uncertainties respectively. The vv gamma gamma and qq gamma gamma data are used to constrain possible anomalous W+W- gamma gamma and ZZ gamma gamma couplings. Combining with previous OPAL results from the W+W- gamma final state, the 95% confidence level limits on the anomalous coupling parameters aoz, acz, aow and acw are found to be: -0.007 GeV^-2 < aoz/Lambda^2 < 0.023 GeV^-2 -0.029 GeV^-2 < acz/Lambda^2 < 0.029 GeV^-2 -0.020 GeV^-2 < aow/Lambda^2 < 0.020 GeV^-2 -0.052 GeV^-2 < acw/Lambda^2 < 0.037 GeV^-2 where Lamdba is the energy scale of the new physics. Limits found when allowing two or more parameters to vary are also presented