1,721,354 research outputs found
Estimating the Sensitivity to New Resonances Decaying to Boosted Quark Pairs and Produced in Association with a Photon in the ATLAS Experiment
No full textParticle physics' most solidified theory is the Standard Model, which includes three of the four known interactions in the Universe, namely the electromagnetic, weak and strong. Although the Standard Model's predictions are repeatedly tested to remarkable accuracy, there are eminent reasons to believe it is not a complete theory of Nature. These consist of the model's inability to incorporate gravity in its description of the fundamental forces, predict non-zero neutrino masses and account for the existence of Dark Matter. Numerous extensions known as beyond the Standard Model physics are proposed and explored by Large Hadron Collider experiments where bounds are set upon them. The study described in this thesis relates to mediators between Standard Model and Dark Matter particles and appraises novel techniques by which such resonances may be investigated with the ATLAS detector. The benchmark model proposes a leptophobic vector boson, , charged under a new gauge symmetry which couples to Standard Model quarks and to Dark Matter Dirac fermions. Its interactions with Dark Matter are infinitesimally rare and thus searches involving such mediators primarily focus on their decays to Standard Model particles, identifiable by Large Hadron Collider detectors. This new type of hardonically-decaying particles remains illusive to current searches due to an extensive multijet background, saturating the trigger scheme. An alternative method is adopted in this thesis. The method uses events wherein an initial-state radiation photon is the trigger object whilst the recoiling resonance is reconstructed from the hadronic final state as a single large-radius jet. These jets are reconstructed with the Hadronic Calorimeter and their energy measurement is of an approximately 3% accuracy. Due to the recoil of the resonance against the photon, the resonance is highly Lorentz-boosted. Hadronically-decaying bosons with high Lorentz boosts can be tagged using substructure observables, targeting their two-pronged characteristic. Using Monte Carlo simulations, selection criteria are optimised. The usefulness of a machine learning tool based on jet substructure observables for tagging two-pronged resonances is tested. Following the optimised selection, Monte Carlo simulations and a control study are used to assess the sensitivity of the ATLAS experiment to the in this channel. Within the control study, data are compared with jet and simulations. Thereby, it is estimated that this scheme bears the potential to discover processes similar to a Standard Model vector boson production in association with a photon and a diquark final state at cross sections as small as 16% and 46% of the and production cross sections, respectively. Finally, using Monte Carlo simulations of processes where for a mass range , the sensitivity to the new resonance is estimated and provided in terms of cross section and coupling confidence level limits
Recent Non-Hadronic Results from ATLAS
No full textMany theories beyond the Standard Model predict new phenomena, such as Z'/W' bosons, and long-lived particles, which decay into leptons. Searches for new physics with such signatures are performed using the ATLAS experiment at the LHC. EFT constraints are also provided where possible to provide maximum useful feedback to the community. The recent Run 2 pp results are reported here
Searches for new physics with leptons using the ATLAS detector
No full textMany theories beyond the Standard Model (SM) predict that New Physics (NP) will manifest by decaying into final states involving leptons. Leptoquarks are predicted by different NP theories to describe similarities between the lepton and quark sectors of the SM. Other NP theories relating to quantum gravity predict periodic signatures in dilepton final states, where tightly-spaced resonance towers detectable at LHC energies provide access to very small couplings through a mechanism coined Clockwork. This talk will present the most recent 13 TeV results of searches for leptoquarks with the ATLAS detector, covering flavour-diagonal and cross-generational final states, as well as a novel search for Clockwork signals in diphoton and dielectron final states
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
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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