1,556 research outputs found

    Z+jets au LHC (calibration des jets et mesure de sections efficaces avec le détecteur ATLAS)

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    La recherche du boson de Higgs ainsi que celle de nouvelle physique aupr√®s du LHC requiert une excellente compr√©hension des processus du Mod√®le Standard du fait de leurs signatures exp√©rimentales similaires. La capacit√© de mesurer le plus pr√©cis√©ment possible l'√©nergie des objets reconstruits dans les d√©tecteurs est par ailleurs primordiale √† la fois pour effectuer des mesures de pr√©cision et pour accro√ģtre la sensibilit√© des analyses √† des signaux de physique au-del√† du Mod√®le Standard. Les travaux pr√©sent√©s dans cette th√®se s'attachent √† ces deux points par l'√©tude d'√©v√©nements contenant un ou plusieurs jets associ√©s √† un boson Z avec le d√©tecteur ATLAS. D'une part, ces √©v√©nements sont utilis√©s pour am√©liorer la calibration en √©nergie des jets de faible impulsion transverse, d'une importance capitale pour les analyses utilisant le d√©nombrement de jets ou leur veto. D'autre part la section efficace diff√©rentielle de production de ces √©v√©nements est mesur√©e en fonction de nombreuses observables et compar√©e √† diverses pr√©dictions th√©oriques. Ces mesures pourront √™tre utilis√©es pour am√©liorer les pr√©dictions qui servent de mod√®les de bruit de fond dans des analyses sur le boson de Higgs et de recherche de physique au-del√† du Mod√®le Standard.The Higgs boson search as well as searches for new physics at the LHC require a very good understanding of Standard Model processes due to their similar experimental signatures. In addition, the ability to precisely measure the energies of reconstructed objects within the detectors is crucial in order to perform precision measurements and to improve the sensitivity to physics signals beyond the Standard Model. The results presented in this thesis address these two points by studying events containing one or several jets associated to a Z boson with the ATLAS detector. These events are used to improve the jet energy calibration in the low transverse momentum regime, which is important for analyses making use of jet counting or jet veto. The differential cross section for the production of such events is also measured as a function of several observables and compared to various theoretical predictions. These measurements will serve to improve the predictions used to model background contamination in Higgs analyses and searches for new phenomena.PARIS11-SCD-Bib. √©lectronique (914719901) / SudocSudocFranceF

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function √į√į¬•with constraints√į √į √į¬• ¬• √įand√į¬ī√į¬• = √į. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Differential cross section measurements for the production of a W boson in association with jets in proton‚Äďproton collisions at ‚ąös = 7 TeV