1,721,119 research outputs found
Searches for the associated production at CMS
No full textAfter the recent discovery of the Higgs boson, the next important goal is to measure its properties. Probing the Yukawa coupling of the Higgs boson to top quarks is a particularly important test of physics beyond the standard model. This coupling can be experimentally accessed by measuring the cross section of the Higgs boson production in association with a top quark pair (). The talk gives an overview of CMS results on searches, using the full dataset of pp-collision data collected at the centre of mass energies of 7 and 8 TeV. All relevant Higgs boson decay modes have been studied, including Higgs decays to b-quarks, photons, -leptons and multi-lepton final states. Additionally, the first Matrix Element Method based analysis has been carried out, that aims to further increase the sensitivity to the signal.After the recent discovery of the Higgs boson, the next important goal is to measure its properties. Probing the Yukawa coupling of the Higgs boson to top quarks is a particularly important test of physics beyond the standard model. This coupling can be experimentally accessed by measuring the cross section of the Higgs boson production in association with a top quark pair (). The talk gives an overview of CMS results on searches, using the full dataset of pp-collision data collected at the centre of mass energies of 7 and 8 TeV. All relevant Higgs boson decay modes have been studied, including Higgs decays to b-quarks, photons, -leptons and multi-lepton final states. Additionally, the first Matrix Element Method based analysis has been carried out, that aims to further increase the sensitivity to the signal
Kehaline enesemääratlus kui õigus eraelu puutumatusele ning võimalike riivete õiguspärasus Euroopa inimõiguste ja põhivabaduste konventsiooni ja inimõiguste kohtu lahendite valguses
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W → τν ristlõike mõõtmine ja τ-leptoniteks laguneva topeltlaetud Higgsi bosoni otsimine CMSi eksperimendis
Get PDFVäitekirja elektrooniline versioon ei sisalda publikatsioone.Elementaarosakeste standardmudel kirjeldab hetkel teadaolevat fundamentaalfüüsikat ning on viimaste aastakümnete jooksul leidnud rohket eksperimentaalset kinnitust. Samas on põhjust arvata, et standardmudel ei ole fundamentaalne alusteooria, vaid pigem jäänuk üldisemast füüsikast, mis avaldub kõrgematel energiatel. Üheks kindlaks viiteks standardmudeli-järgse füüsika kohta on neutriinode nullist erinevad massid, mis on võrreldes teiste standardmudeli osakeste massidega väga väikesed.
LHC (Large Hadron Collider) on maailma suurim elementaarosakeste kiirendi, mis töötab kõrgemal energial kui ükski varasem eksperiment. LHC kiirendi üldisteks eesmaärkideks on nii uue füüsika ja Higgsi bosoni otsimine kui ka standardmudeli protsesside uurimine ja täppismõõtmised. Kiirendi paikneb 27 km. pikkuses ringikujulises tunnelis, mis koosneb magnetitest, milles ringlevad kaks vastassuunalist prootonkiirt. Prootonite interaktsioonipunktides paiknevad osakeste-detektorid, kus toimub põrgete edasine analüüs. Käesolevas doktoritöös kirjeldatud analüüsid on teostatud CMS (Compact Muon Solenoid) detektori poolt kogutud andmetega.
W-bosoni ristloõike mõõtmine τ-leptoni ja neutriino lagunemiskanalis on üks teadaolevatest standardmudeli protsessidest. τ-leptoniteks laguneva topeltlaetud Higgsi bosoni otsimine baseerub uuel füüsikateoorial, mis üritab seletada neutriinode väikseid, kuid nullist erinevaid masse. Analüüsitud eksperimentaalsed andmed on standardmudeliga kooskoõlas: mõõdetud W-bosoni ristloõige vastab teoorias arvutatud väärtusele ning topeltlaetud Higgsi bosoni võimaliku signaali otsing annab uue massi alampiiri, mis parandab oluliselt eelmist Tevatroni kiirendis saadud tulemust.The standard model of particle physics describes known matter and fundamental interactions and has been experimentally verified to a great level of accuracy. However, it is generally believed that the SM is not a complete theory, but needs to be extended. One of the clear indications of physics beyond the standard model are nonzero neutrino masses, that are extremely small in comparison to the masses of other particles.
The Large Hadron Collider (LHC) is the worlds largest particle collider that works at higher energies than ever achieved in previous experiments and tries to find answers to the most fundamental questions in modern physics like the origin of mass, dark matter or nonzero neutrino masses. The LHC is situated in the 27 km long circular tunnel and is composed of a ring of magnets that store two counter-rotating proton beams. The proton collisions are measured and further analyzed by several particle detectors that are situated at the collision points of the proton beams. The data collected by one of the large general-purpose experiments – Compact Muon Solenoid (CMS) – were used in the two analyses that are summarized in this thesis.
Firstly, the measurement of the cross section of a W- boson decaying to a τ-lepton and a neutrino, is one of the known standard model processes. The measurement confirms the standard model and is a contribution to τ-lepton physics in CMS.
The search for a doubly charged Higgs boson that decays to τ-leptons tests new beyond the standard model physical theory, that is related to the neutrino mass generation mechanism. Analyzed data was found to be in good agreement with the standard model prediction and a new lower bound on the doubly charged Higgs boson mass was set, which considerably improves the previous measurements
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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