4,797 research outputs found
Search for single top quark production through FCNC at ATLAS experiment
No full textFlavour changing neutral currents (FCNC) are strongly suppressed in the Standard Model (SM). Although absent at tree level, small FCNC contributions are expected at one-loop level. For the top quark, the expected FCNC branching fractions to gauge bosons, e.g. +gluon, are predicted to be at the level of ~\cite{Eilam:1990zc}. There are, howevre, extensions of the SM which predict the presence of FCNC contributions and significantly enhance the FCNC rates compared to the SM predictions. ATLAS has studied direct single top-quark production through FCNC ~\cite{Alhroob:1329491}, where the u(c) quark interacts with a gluon to produce a single top quark, and then top quark decays via SM process,
Automatic test cases generation from software specifications modules
No full textA new technique is proposed in this paper to extend the Integrated Classification Tree Methodology (ICTM) developed by Chen et al. [13] This software assists testers to construct test cases from functional specifications. A Unified Modelling Language (UML) class diagram and Object Constraint Language (OCL) are used in this paper to represent the software specifications. Each classification and associated class in the software specification is represented by classes and attributes in the class diagram. Software specification relationships are represented by associated and hierarchical relationships in the class diagram. To ensure that relationships are consistent, an automatic methodology is proposed to capture and control the class relationships in a systematic way. This can help to reduce duplication and illegitimate test cases, which improves the testing efficiency and minimises the time and cost of the testing. The methodology introduced in this paper extracts only the legitimate test cases, by removing the duplicate test cases and those incomputable with the software specifications. Large amounts of time would have been needed to execute all of the test cases; therefore, a methodology was proposed which aimed to select a best testing path. This path guarantees the highest coverage of system units and avoids using all generated test cases. This path reduces the time and cost of the testing
Software test case generation from system models and specification. Use of the UML diagrams and High Level Petri Nets models for developing software test cases.
No full textThe main part in the testing of the software is in the generation
of test cases suitable for software system testing. The quality of the
test cases plays a major role in reducing the time of software system
testing and subsequently reduces the cost. The test cases, in model de-
sign stages, are used to detect the faults before implementing it. This
early detection offers more
flexibility to correct the faults in early stages
rather than latter ones. The best of these tests, that covers both static
and dynamic software system model specifications, is one of the chal-
lenges in the software testing. The static and dynamic specifications
could be represented efficiently by Unified Modelling Language (UML)
class diagram and sequence diagram. The work in this thesis shows that
High Level Petri Nets (HLPN) can represent both of them in one model.
Using a proper model in the representation of the software specifications
is essential to generate proper test cases.
The research presented in this thesis introduces novel and automated
test cases generation techniques that can be used within a software sys-
tem design testing. Furthermore, this research introduces e cient au-
tomated technique to generate a formal software system model (HLPN)
from semi-formal models (UML diagrams). The work in this thesis con-
sists of four stages: (1) generating test cases from class diagram and
Object Constraint Language (OCL) that can be used for testing the
software system static specifications (the structure) (2) combining class
diagram, sequence diagram and OCL to generate test cases able to cover
both static and dynamic specifications (3) generating HLPN automat-
ically from single or multi sequence diagrams (4) generating test cases
from HLPN.
The test cases that are generated in this work covered the structural
and behavioural of the software system model. In first two phases of this
work, the class diagram and sequence diagram are decomposed to nodes
(edges) which are linked by Classes Hierarchy Table (CHu) and Edges
Relationships Table (ERT) as well. The linking process based on the
classes and edges relationships. The relationships of the software system
components have been controlled by consistency checking technique, and
the detection of these relationships has been automated. The test cases
were generated based on these interrelationships. These test cases have
been reduced to a minimum number and the best test case has been
selected in every stage. The degree of similarity between test cases is
used to ignore the similar test cases in order to avoid the redundancy.
The transformation from UML sequence diagram (s) to HLPN facilitates
the simpli cation of software system model and introduces formal model
rather than semi-formal one. After decomposing the sequence diagram
to Combined Fragments, the proposed technique converts each Combined
Fragment to the corresponding block in HLPN. These blocks are con-
nected together in Combined Fragments Net (CFN) to construct the the
HLPN model. The experimentations with the proposed techniques show
the effectiveness of these techniques in covering most of the software
system specifications
Search for New Physics in Single Top Channel at the LHC
No full textAt the seventh International Workshop on the CKM Unitarity Triangle, a talk on the search for new physics in single top quark production at the LHC experiments was presented. Three analysis were shown: the search for single top quark production through FCNC processes performed by the ATLAS Collaboration, the search for boson by ATLAS Collaboration using the resonance using the invariant mass distribution of the system and the search for boson done by CMS Collaboration using boosted decision tree and the invariant mass distribution of the system
Search for FCNC in single-top quark production in ATLAS
No full textFlavour Changing Neutral Currents (FCNC) are strongly suppressed in the Standard Model due to the Glashow-Iliopoulos-Maiani (GIM) mechanism. Although absent at tree level, small FCNC contributions are expected at one-loop level, determined by the CKM mixing. For the top quark, within the framework of the Standard Model, the expected FCNC branching fractions to gauge bosons, e.g. tq+gluon, are predicted to be at the level of . There are, however, extensions of the SM, like supersymmetry (SUSY) and the 2-Higgs doublet model, which predict the presence of FCNC contributions already at tree level and significantly enhance the FCNC decay branching ratios compared to the Standard Model predictions. This analysis concentrates on single top-quark production through FCNC, where the u(c) quark interacts with a gluon to produce a single top quark without any associated production. The top quark then decays as usual via the SM process, tW+b, An upper limit on the production cross section at 95% confidence level has been extracted using 35 from the first ATLAS data taken in 2010
Single-top quark measurements at ATLAS
No full textATLAS has performed very well in 2010 and 2011, the three standard model single-top channel were studied carefully, the t-channel was discovered at ATLAS using 165 pb^{-1} of data, and the cross section was re-measured to be 90^{32}_{-22}pb using 700 pb^{-1} of data. the Wt-channel has been studied, and upper limit at 95% C.L. on the cross-section was calculated, the limits were 158pb and 39 pb for lepton+jets and Dileption channels respectively. the single-top s-channel was also studies at ATLAS for the first time, an upper limit was calculated for its cross-section and it was 26.5 pb at 95% C.L. In addition to the SM single-top, the flavor changing neutral current through single-top quark was analysed using 35 pb^{-1} of data collected in 2010, the signal was not seen and an upper limit on the cross-section was calculated and it was 17.3 pb
Author Correction: A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery
No full textIn the version of this article initially published, the ATLAS Collaboration
author names, affiliations and acknowledgements were omitted and
have now been included in the HTML and PDF versions of the article
Top quark cross section measurement in ATLAS: Commissioning Analysis
No full textAn accurate determination of the top‐quark pair production cross‐section at the LHC provides a valuable check of the Standard Model. In this article we present a commissioning analysis to measure to quark cross section with the ATLAS detector. The cross section is determined in the semileptonic channel using a counting method, based solely on counting the numbers of top candidate events that pass selection, and subtracting all backgrounds in order to get the yield of tt̄ events in the sample. Our cross section study is performed without relying on the tagging of b‐quark initiated jets
Search for a CP-odd Higgs boson decaying to Zh in pp collisions at root s=8 TeV with the ATLAS detector
No full textSee paper for full list of authors – 13 pages plus author list + cover pages (30 pages total), 5 figures, 2 tables, submitted to Phys. Lett. B, All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2013-06/International audienceA search for a heavy, CP-odd Higgs boson, , decaying into a boson and a 125 GeV Higgs boson, , with the ATLAS detector at the LHC is presented. The search uses proton--proton collision data at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb. Decays of CP-even bosons to or pairs with the boson decaying to electron or muon pairs are considered, as well as decays with the boson decaying to neutrinos. No evidence for the production of an boson in these channels is found and the 95% confidence level upper limits derived for \sigma (gg\rightarrow A) \times \mbox{BR}(A \rightarrow Zh) \times \mbox{BR}(h \rightarrow f\bar{f}) are 0.098--0.013 pb for and 0.57--0.014 pb for in a range of 220--1000 GeV. The results are combined and interpreted in the context of two-Higgs doublet models
Search for excited electrons and muons in √s=8 TeV proton–proton collisions with the ATLAS detector
No full textThe ATLAS detector at the Large Hadron Collider is used to search for excited electrons and excited muons in the channel pp → ℓℓ* → ℓℓγ, assuming that excited leptons are produced via contact interactions. The analysis is based on 13 fb[superscript −1] of pp collisions at a centre-of-mass energy of 8 TeV. No evidence for excited leptons is found, and a limit is set at the 95% credibility level on the cross section times branching ratio as a function of the excited-lepton mass m[subscript ℓ*]. For m[subscript ℓ*] ≥ 0.8 TeV, the respective upper limits on σB(ℓ* → ℓγ) are 0.75 and 0.90 fb for the e* and μ* searches. Limits on σB are converted into lower bounds on the compositeness scale Λ. In the special case where Λ = m[subscript ℓ*], excited-electron and excited-muon masses below 2.2 TeV are excluded.United States. Dept. of EnergyNational Science Foundation (U.S.)Brookhaven National Laborator
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