scholarly journals Charge Asymmetry in Top Quark Pair Production

Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1278
Author(s):  
Roman Lysák
Keyword(s):  
Elementary Particle ◽  
Pair Production ◽  
Top Quark ◽  
Charge Asymmetry ◽  
New Physics ◽  
Current Theory ◽  
Elementary Particles ◽  
Standard Deviations ◽  
Theoretical Side

The top quark is the heaviest elementary particle known. It has been proposed many times that new physics beyond the current theory of elementary particles may reveal itself in top quark interactions. The charge asymmetry in the pair production of a fermion and its antiparticle has been known for many decades. Early measurements of such asymmetry in top quark pair production showed a disagreement with the prediction by more than 3 standard deviations. Many years of an effort on both experimental and theoretical side have allowed to understand the top quark pair charge asymmetry better and to bring back the agreement between the measurements and the theory. In this article, these efforts are reviewed together with the discussion about a potential future of such measurements.

scholarly journals Measurement of the charge asymmetry in top quark pair production inppcollisions ats=8  TeVusing a template method

2016 ◽  
Vol 93 (3) ◽  
Author(s):  
V. Khachatryan ◽  
A. M. Sirunyan ◽  
A. Tumasyan ◽  
W. Adam ◽  
E. Asilar ◽  
...  
Keyword(s):  
Pair Production ◽  
Top Quark ◽  
Charge Asymmetry ◽  
Template Method

scholarly journals NLO QCD corrections to off-shell $${t{\bar{t}}W^\pm }$$ production at the LHC: correlations and asymmetries

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Giuseppe Bevilacqua ◽  
Huan-Yu Bi ◽  
Heribertus Bayu Hartanto ◽  
Manfred Kraus ◽  
Jasmina Nasufi ◽  
...  
Keyword(s):  
Top Quark ◽  
Charge Asymmetry ◽  
New Physics ◽  
Atlas Collaboration ◽  
Narrow Width Approximation ◽  
Theoretical Predictions ◽  
Top Quark Decay ◽  
Quark Decay ◽  
Precision Observables ◽  
The Impact

AbstractRecent discrepancies between theoretical predictions and experimental data in multi-lepton plus b-jets analyses for the $$t{\bar{t}}W^\pm $$ t t ¯ W ± process, as reported by the ATLAS collaboration, have indicated that more accurate theoretical predictions and high precision observables are needed to constrain numerous new physics scenarios in this channel. To this end we employ NLO QCD computations with full off-shell top quark effects included to provide theoretical predictions for the $$\mathcal{R}= \sigma _{t{\bar{t}}W^+}/\sigma _{t{\bar{t}}W^-}$$ R = σ t t ¯ W + / σ t t ¯ W - cross section ratio at the LHC with $$\sqrt{s}=13$$ s = 13 TeV. Depending on the transverse momentum cut on the b-jet we obtain 2–3% theoretical precision on $$\mathcal{R}$$ R , which should help to shed some light on new physics effects that can reveal themselves only once sufficiently precise Standard Model theoretical predictions are available. Furthermore, triggered by these discrepancies we reexamine the charge asymmetry of the top quark and its decay products in the $$t{\bar{t}}W^\pm $$ t t ¯ W ± production process. In the case of charge asymmetries, that are uniquely sensitive to the chiral nature of possible new physics in this channel, theoretical uncertainties below 15% are obtained. Additionally, the impact of the top quark decay modelling is scrutinised by explicit comparison with predictions in the narrow-width approximation.

scholarly journals Signs of new physics in top quark pair production associated with a neutrino pair at the LHC

2020 ◽  
Vol 101 (9) ◽  
Author(s):  
Daruosh Haji Raissi ◽  
Javad Ebadi ◽  
Mojtaba Mohammadi Najafabadi
Keyword(s):  
Pair Production ◽  
Top Quark ◽  
New Physics ◽  
Neutrino Pair

scholarly journals Measurement of the charge asymmetry in highly boosted top-quark pair production in s=8 TeV pp collision data collected by the ATLAS experiment

2016 ◽  
Vol 756 ◽  
pp. 52-71 ◽  
Author(s):  
G. Aad ◽  
B. Abbott ◽  
J. Abdallah ◽  
O. Abdinov ◽  
B. Abeloos ◽  
...  
Keyword(s):  
Pair Production ◽  
Top Quark ◽  
Charge Asymmetry ◽  
Atlas Experiment ◽  
8 Tev

scholarly journals Top quark studies with the ATLAS detector

2015 ◽  
Vol 39 ◽  
pp. 1560092
Author(s):  
Marcella Capua
Keyword(s):  
Pair Production ◽  
Cross Sections ◽  
Top Quark ◽  
W Boson ◽  
Production Cross ◽  
Charge Asymmetry ◽  
Atlas Detector ◽  
Top Quark Production ◽  
Top Pair Production ◽  
8 Tev

The latest top quark studies in proton-proton collisions at a centre-of-mass energy of 7 and 8 TeV with the ATLAS detector are reported. We present recent results on the top pair production inclusive cross-sections, top pair production differential cross-section in the resolved and boosted regimes, single top-quark production cross-sections measured in the t-channel, s-channel and W-boson associated processes, as well as the determination of the CKM matrix element [Formula: see text]. The results are compared with theoretical expectations. Latest ATLAS results on top properties will be also shown in terms of direct and pole mass, spin correlations and charge asymmetry.

THE "TOP PRIORITY" AT THE LHC

2008 ◽  
Vol 23 (25) ◽  
pp. 4107-4124 ◽  
Author(s):  
TAO HAN
Keyword(s):  
Elementary Particle ◽  
Top Quark ◽  
Hadron Collider ◽  
Top Quarks ◽  
New Physics ◽  
Great Accuracy ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
High Luminosity ◽  
The Standard Model

The LHC (Large Hadron Collider) will be a top-quark factory. With 80 million pairs of top quarks and an additional 34 million single tops produced annually at the designed high luminosity, the properties of this particle will be studied to a great accuracy. The fact that the top quark is the heaviest elementary particle in the Standard Model with a mass right at the electroweak scale makes it tempting to contemplate its role in electroweak symmetry breaking, as well as its potential as a window to unknown new physics at the TeV scale. We summarize the expectations for top-quark physics at the LHC, and outline new physics scenarios in which the top quark is crucially involved.

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