И ТЯЖЕЛОГО НЕЙТРИНО НА БОЛЬШОМ АДРОННОМ КОЛЛАЙДЕРЕДан краткий обзор SUc(3)⊗SUL( 2)⊗SUR( 2)⊗U (1) лево-право-симметричной калибровочной модели.Обсуждается возможность детектирования правого WR-бозона и тяжелого нейтрино в pp-столкновениях на Большом адронном коллайдере.Приведены ограничения на массу WR-бозона и тяжелого нейтрино, полученные на основе анализа экспериментальных данных детекторов CMS и ATLAS с полной энергией сталкивающихся протонов 7-8 ТэВ.Ключевые слова: лево-правая симметрия, Большой адронный коллайдер, поиск новой физики.

We study the Large Hadron Collider (LHC) discovery potential for Z' models with continuously distributed mass for root s = 7, 10 and 14 TeV centre-of mass energies. One of possible LHC signatures for such models is the existence of broad resonance structure in Drell-Yan reaction pp -> Z' + ... -> l(+)l(-) + ...

For Poisson distribution $Pois(n, \lambda)$ with $\lambda \gg 1$, $n \gg 1$ we propose to determine significance as $S = \frac{n_{obs}-\lambda}{\sqrt{\lambda}}$. The significance $S$ coincides up to sign with often used significance. For experiments which measure the same quantities the natural but not unique rule for significance combining is $S_{comb}(S_1, S_2) = \frac{S_1\sigma_1+S_2\sigma_2}{\sqrt{\sigma^2_1+\sigma^2_2}}$, where $\sigma_1$ and $\sigma_2$ are variations. We also propose the rule for significances combining for the case with systematic errors.

We discuss phenomenological consequences of renormalizable Z' models with continuously distributed mass. We point out that one of the possible LHC signatures for such model is the existence of broad resonance in Drell–Yan reaction pp →Z' →l+l-.

Results of numerical procedure of constructing confidence intervals for parameter of the Poisson distribution of signal events in the presence of background events with known value of parameter of Poisson distribution are presented. It is shown that the used procedure has both the Bayesian and frequentist interpretations. Also the possibility to construct a continuous analogue of the Poisson distribution to search the bounds of confidence intervals for the parameter of the Poisson distribution is discussed.

Statistical Problems in Particle Physics, Astrophysics and Cosmology, pp. 106-107 (2006) No AccessPROGRAM FOR EVALUATION OF SIGNIFICANCE, CONFIDENCE INTERVALS AND LIMITS BY DIRECT CALCULATION OF PROBABILITIESS. I. BITYUKOV, S. E. EROFEEVA, N. V. KRASNIKOV and A. N. NIKITENKOS. I. BITYUKOVInstitute for high energy physics, 142281 Protvino, Russia, S. E. EROFEEVAMoscow State Academy of Instrument Engineering and Computer Science, Moscow, Russia, N. V. KRASNIKOVInstitute for nuclear research RAS, 117312 Moscow, Russia and A. N. NIKITENKOImperial College, London, United Kingdomon leave from ITEP, Moscowhttps://doi.org/10.1142/9781860948985_0024Cited by:3 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail Abstract: We propose a program which allows one to estimate significance, confidence intervals and limits, taking into account systematics and statistical uncertainties of variables described by Poisson distributions. The given program can be used for combining searches. The motivation of the direct probabilities calculations is determined by two reasons. Firstly, the tail of a Poisson distribution is heavier than that of a normal distribution. In the case of small probabilities the Gaussian approximation gives the wrong values of estimators. Secondly, the estimators which are constructed on the basis of the likelihood ratio often have poor statistical properties. FiguresReferencesRelatedDetailsCited By 3Evaluation of three methods for calculating statistical significance when incorporating a systematic uncertainty into a test of the background-only hypothesis for a Poisson processRobert D. Cousins, James T. Linnemann and Jordan Tucker1 Oct 2008 | Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 595, No. 2Using the e ± µ∓ + E T miss signature in the search for supersymmetry and lepton-flavor violation in neutralino decaysYu. M. Andreev, S. I. Bityukov, N. V. Krasnikov and A. N. Toropin1 Oct 2007 | Physics of Atomic Nuclei, Vol. 70, No. 10Search for the MSSM A → Zh decay withG Anagnostou and G Daskalakis11 April 2007 | Journal of Physics G: Nuclear and Particle Physics, Vol. 34, No. 5 Statistical Problems in Particle Physics, Astrophysics and CosmologyMetrics History PDF download

We investigate squark and gluino pair production at LHC (CMS) with subsequent decays into quarks, leptons and LSP in models with effective supersymmetry where third generation of squarks is relatively light while the first two generations of squarks are heavy. We consider the general case of nonuniversal gaugino masses. Visibility of signal by an excess over SM background in $(n \geq 2)jets + (m \geq 0)leptons + E^{miss}_T$ events depends rather strongly on the relation between LSP, second neutralino, gluino and squark masses and it decreases with the increase of LSP mass.

We describe the search for new physics to be performed at the Large Hadron Collider.

We review the results on the investigation of the LHC(CMS) SUSY discovery potential for the case of nonuniversal gaugino and squark masses.

We investigate \chi^{+/-}_1 \chi^0_2 pair production at LHC (CMS) with subsequent decays into leptons for the case of nonuniversal gaugino masses. Visibility of signal by an excess over SM background in 3 leptons + no jet + E^{miss}_T events depends rather strongly on the relation between LSP mass \chi^0_1 and \chi^{+/-}_1 mass. We also give some preliminary results on the investigation of squark and gluino production at LHC for the case of nonuniversal gaugino masses.

We propose a method to estimate the probability of new physics discovery in future high energy physics experiments. Physics simulation gives both the average numbers $ $ of background and $ $ of signal events. We find that the proper definition of the significance is $S_{12} = \sqrt{ + } - \sqrt{ }$ in comparison with often used significances $S_1 = \displaystyle \frac{ }{\sqrt{ }}$ and $S_2 = \displaystyle \frac{ }{\sqrt{ + }}$. We propose a method for taking into account systematic uncertainties related to nonexact knowledge of background and signal cross sections. An account of such systematics is very essential in the search for supersymmetry at LHC. We propose a method for estimation of exclusion limits on new physics in future experiments. We also estimate the probability of new physics discovery in future experiments taking into account systematical errors.

We show that the search for supersymmetry at LHC will be very problematic for the particular case of nonuniversal relations among gaugino masses. Namely, if gluino, first chargino and LSP masses are closed to each other it would be very difficult to discover supersymmetry even if sparticle masses are lighter than 1 TeV.