1,721,071 research outputs found
Potraga za novim skalarnim rezonancijama u sudarima protona zabilježenima detektorom CMS na velikom hadronskom sudarivaču
No full textIn this thesis, the search for the resonant production of a new massive scalar particle X decaying into a new light scalar particle Y and a standard model Higgs boson H through the process X → YH → bƃbƃ is presented. Data from CERN LHC proton-proton collisions at a centre-of-mass energy of 13 TeV are used, collected by the CMS detector in 2016–2018 and amounting to 138 fb^−1 of integrated luminosity. The search is performed in mass ranges of X (0.9–4 TeV) and Y (60–600 GeV) where both the Y and the H are highly Lorentz-boosted. In this kinematic regime, their b quark-antiquark daughter particles are collimated enough to allow the reconstruction of H and Y using single large area jets each. The mass of one of the large-area jets is required to be compatible with that of the Higgs boson, which is 125 GeV. A scan is performed in a two-dimensional plane spanned by the mass of the other jet, associated to Y, and the invariant mass of both large-area jets used to reconstruct X. The results are interpreted in the context of scalar resonances predicted in the next-to-minimal supersymmetric standard model and also in an extension of the standard model with two additional singlet scalar fields. Upper limits are placed on the production cross section of the process as a function of the masses of X and Y in the 0.1–150 fb range. This is the first search for this process using Lorentz-boosted event topologies and significantly extends the constraints on the studied model. A novel calibration method of the ParticleNet algorithm designed to recognize the decays of a massive particle into a pair of b quarks is also presented. The calibration consists of selecting events with a large-area jet with high momentum and measuring the strength of the Z boson peak on a smooth hadronic background. Previously used method performed the calibration on a set of jets originating from gluon fragmentation into bƃ, with special selection applied to make them more akin to the jets originating from the decays of a massive particle, such as Z or H. The presented measurement demonstrates the possibility of a direct calibration of the tagger and provides a validity test for previously used, indirect measurements.U ovom je radu opisana potraga za kaskadnim raspadom teške skalarne čestice X u drugu skalarnu česticu Y i Higgsov bozon H gdje se obje dalje raspadaju u par b kvarkova. Raspadi čestice X u dvije skalarne čestice različitih masa predviđeni su u mnoštvu BSM teorija, ali su uglavnom neistraženi na LHC-u. Potraga je napravljena u rasponu masa 0.9–4 TeV za X i 60–600 GeV za Y, fokusirajući se na kinematički režim gdje Y i H imaju visoki pT te se produkti njihovih raspada mogu rekonstruirati kao jedinstveni široki mlazovi. Potraga koristi podatke proton-proton sudara na energiji od 13 TeV u sustavu centra mase, prikupljene CMS eksperimentom na LHC-u. Podaci su prikupljeni u 2016– 2018 i ukupna količina podataka iznosi 138 fb^−1. Od 260 različitih testiranih (M_X,M_Y) hipoteza, ona s najvećom značajnošću opažanja od 3.1σ je M_X = 1.6TeV i M_Y = 90GeV. Globalna značajnost takvog opažanja je 0.7σ. Također su postavljene i gornje granice na udarni presjek traženog procesa sa sigurnošću intervala pouzdanosti od 95% u rasponu 0.1–150 fb, ovisno oM_X iM_Y. Postavljene granice su uspoređene s najvećim dopuštenim udarnim presjecima u NMSSM i TRSM teorijama što dovodi do isključenja dijela faznog prostora teorija za određene M_X i M_Y. Za NMSSM, područje isključenja obuhvaća raspone M_X 1000–1150 GeV i 101–145 GeV za M_Y. Za TRSM, područje isključenja je unutar 950 < M_X < 1330GeV i 110 < M_Y < 132GeV. Gornje granice su također uspoređene s drugim relevantnim mjerenjima i pokazano je da predstavljeni rezultati značajno poboljšavaju prethodne rezultate. Također je u radu predstavljena i kalibracija ParticleNet algoritma za dvije radne točke. Kalibracija se sastoji od mjerenja Z rezonancije na pozadini QCD događaja. Ključna komponenta mjerenja su korekcije idućeg reda računa smetnje primijenjene na simulaciju Z i W događaja koja koristi najniži red računa smetnje. Rezultati dobiveni ovom, novom, metodom uspoređeni su s postojećim rezultatima koji koriste same QCD događaje za kalibraciju. Rezultati potvrđuju slaganje između dviju metoda
Studija Lorentz-potisnutih Higgsovih bozona u procesima produkcije parova Higgsovih bozona na velikom hadronskom sudaraču u CERN-u
No full textHiggs boson pair production is recently a very relevant topic in high energy physics. Experiments at CERN's Large Hadron Collider are searching for HH production are with mainly two objectives: to observe the process as described by the standard model or to discover beyondstandard model physics in the form of a resonance particle that decays to HH pairs. Candidates for beyond-standard model resonance particles are mainly the spin-2 graviton and the spin-0 scalar. Massive resonances decaying to HH pairs can impart a signicant Lorentz-boost to them, which in turn boosts the decay products of the Higgs bosons themselves. The largest branching fraction of the Higgs boson decay is to a pair of bottom quarks and antiquarks (bb), which is frequently used to econstruct the Higgs boson. The signature of a boosted Higgs boson using the bb decay channel is a particle jet originating from the fragmentation and hadronization of the bb pairs, with the jet mass corresponding to the Higgs boson mass of 125 GeV (a \Higgs jet"). In b quark decay, about 20% of the the decay products yields a lepton (electron or a muon) with an associated undetected neutrino. The escaping neutrino results in the mass resolution of the Higgs jet being degraded, thus making observations less sensitive. The purpose of this work is to study some boosted Higgs boson production processes using Monte Carlo simulations and to estimate a correction for the Higgs jet mass in order to improve its resolution using a boosted decision tree regression
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Search for exotic heavy top and bottom quark partners with CMS
No full textWe present searches for massive top and bottom quark partners at CMS using data collected at sqrt(s)=8 TeV. Such partners can be found in models predicting vector-like quarks to solve the hierarchy problem and stabilize the Higgs boson mass. The searches span a range of final states, from multi-leptonic to entirely hadronic, and limits are set on mass and production cross sections as a function of branching ratios.We present searches for massive top and bottom quark partners at CMS using LHC pp collision data collected at centre-of-mass energy TeV. Such partners can be found in models predicting vector-like quarks to solve the hierarchy problem and stabilize the Higgs boson mass. The searches span a range of final states containing several lepton and jet multiplicities, and limits were set on mass and production cross sections as a function of branching ratios
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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