Measurement of top quark top anti-quark production cross-section and search for new physics beyond the standard model

1998 ◽  
Author(s):  
Sailesh Chopra
2007 ◽  
Vol 22 (38) ◽  
pp. 2873-2884
Author(s):  
DANIEL WHITESON

The dilepton decays of the top quark are a powerful laboratory for probing the Standard Model and searching for hints of a more fundamental theory. We present a detailed analysis of the production cross section and the kinematic qualities of top quark pair candidate events in [Formula: see text] collisions at [Formula: see text] = 1.96 TeV collected by the CDF detector which include two leptons in the final state, suggesting the decay [Formula: see text]. We describe the selection of candidate events to suppress major backgrounds and present the number of observed events over background. As a test of the top quark hypothesis, the kinematics of the events are analyzed via a measurement of M top with unprecedented precision.


2021 ◽  
pp. 11-13
Author(s):  
T.V. Obikhod ◽  
E.A. Petrenko

As part of the search for new physics beyond the Standard Model, we chose the determination of the Higgs boson decay width as one of the least experimentally determined values. The decay widths into the four fermions of the lightest and heaviest CP-even Higgs bosons of the THDM model were calculated, taking into account QCD and electroweak corrections in the NLO approximation. To achieve this goal, the program Monte Carlo Prophecy 4f with special scenarios of parameters, 7B1 and 5B1 were used. It was found that the decay width of the heavier CPeven Higgs boson H differs from HSM by 1227.93 times and changes to a negative value when deviating from the standard scenarios. Scale factors kZ2 and kW2 showed the predominance of the associated with Z boson production cross section of CP-even Higgs boson over the associated with W production cross section.


2019 ◽  
Vol 34 (38) ◽  
pp. 2050065
Author(s):  
Gabriel Facini ◽  
Kyrylo Merkotan ◽  
Matthias Schott ◽  
Alexander Sydorenko

Fiducial production cross-section measurements of Standard Model processes, in principle, provide constraints on new physics scenarios via a comparison of the predicted Standard Model cross-section and the observed cross-section. This approach received significant attention in recent years, both from direct constraints on specific models and the interpretation of measurements in the view of effective field theories. A generic problem in the reinterpretation of Standard Model measurements is the corrections application of to data to account for detector effects. These corrections inherently assume the Standard Model to be valid, thus implying a model bias of the final result. In this work, we study the size of this bias by studying several new physics models and fiducial phase–space regions. The studies are based on fast detector simulations of a generic multi-purpose detector at the Large Hadron Collider. We conclude that the model bias in the associated reinterpretations is negligible only in specific cases, however, typically on the same level as systematic uncertainties of the available measurements.


2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Xi-Yan Tian ◽  
Liu-Feng Du ◽  
Yao-Bei Liu

AbstractThe vectorlike top partners are potential signature of some new physics beyond the Standard Model at the TeV scale. In this paper, we propose to search for the vectorlike T quark with charge 2/3 in the framework of a simplified model where the top partners only couples with the third generation of Standard Model quarks. We investigate the observability for electroweak production of a vectorlike T quark in association with a standard model bottom quark through the process $$pp \rightarrow T\bar{b}j$$ p p → T b ¯ j with the subsequent decay mode of $$T\rightarrow t(\rightarrow b W^+\rightarrow b \ell ^{+} \nu _{\ell })h( \rightarrow \gamma \gamma )$$ T → t ( → b W + → b ℓ + ν ℓ ) h ( → γ γ ) , at the proposed High Energy Large Hadron Collider (HE-LHC) and Future Circular Collider in hadron-hadron mode (FCC-hh) including the realistic detector effects. The 95% confidence level excluded regions and the $$5\sigma $$ 5 σ discovery reach in the parameter plane of $$\kappa _{T}-m_T$$ κ T - m T , are respectively obtained at the HE-LHC with the integrated luminosity of 15 ab$$^{-1}$$ - 1 and the FCC-hh with the integrated luminosity of 30 ab$$^{-1}$$ - 1 . We also analyze the projected sensitivity in terms of the production cross section times branching fraction at the HE-LHC and FCC-hh.


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