scholarly journals Top physics at the LHC

2015 ◽  
Vol 30 (35) ◽  
pp. 1530063 ◽  
Author(s):  
Vittorio Del Duca ◽  
Eric Laenen
Keyword(s):  
Top Quark ◽  
Charge Asymmetry ◽  
Top Physics ◽  
Present Situation ◽  
Top Quark Mass ◽  
Single Top ◽  
Key Concepts ◽  
Theoretical Predictions ◽  
Top Quark Decay ◽  
Quark Decay

We review the present situation in top quark physics, in these early days of Run II of the LHC. We take mostly a Standard Model perspective, showing recent results, and review the key concepts and results of the associated theoretical predictions. The issues we discuss are the top quark mass, top quark pair and single top production, production in association with other particles, charge asymmetry and top quark decay.

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 TOP AND HIGGS PHYSICS AT THE HADRON COLLIDERS

2013 ◽  
Vol 28 (26) ◽  
pp. 1330038 ◽  
Author(s):  
SHABNAM JABEEN
Keyword(s):  
Top Quark ◽  
Hadron Collider ◽  
Center Of Mass ◽  
Charge Asymmetry ◽  
Mass Energy ◽  
Top Quark Mass ◽  
Proton Antiproton ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Single Top

This review summarizes the recent results for top quark and Higgs boson measurements from experiments at Tevatron, a proton–antiproton collider at a center-of-mass energy of [Formula: see text], and the Large Hadron Collider, a proton–proton collider at a center-of-mass energy of [Formula: see text]. These results include the discovery of a Higgs-like boson and measurement of its various properties, and measurements in the top quark sector, e.g. top quark mass, spin, charge asymmetry and production of single top quark.

OBSERVATION OF THE TOP QUARK

1996 ◽  
Vol 11 (21) ◽  
pp. 3819-3848
Author(s):  
SOO-BONG KIM
Keyword(s):  
Top Quark ◽  
Quark Mass ◽  
Production Cross ◽  
Top Quark Mass ◽  
Text Production ◽  
Top Quark Production ◽  
Top Quark Decay ◽  
Quark Production ◽  
Quark Decay ◽  
Kinematic Properties

Top-quark production is observed in [Formula: see text] collisions at [Formula: see text] at the Fermilab Tevatron. The CDF and DØ collaborations observe signals consistent with [Formula: see text] to [Formula: see text] but inconsistent with the background prediction by 4.8σ (CDF) and 4.6σ (DØ). Additional evidence for the top quark is provided by a peak in the reconstructed mass distribution. The kinematic properties of the excess events are consistent with the top-quark decay. The top-quark mass has been measured to be 176±8 (stat.) ±10 (sys.) GeV /c2 (CDF) and [Formula: see text]±22(sys.)GeV/c2 (DØ), and the [Formula: see text]-production cross section to be [Formula: see text] and 6.4±2.2 pb (DØ).

scholarly journals POSSIBLE EXISTENCE OF TOPPED HADRONS

1995 ◽  
Vol 10 (22) ◽  
pp. 3143-3153
Author(s):  
TOSHIAKI ITO ◽  
SHOJI SAWADA
Keyword(s):  
Binding Energy ◽  
Top Quark ◽  
Quark Mass ◽  
Bound States ◽  
Vacuum Expectation ◽  
Higgs Doublet ◽  
Top Quark Mass ◽  
Unitarity Bound ◽  
Top Quark Decay ◽  
Quark Decay

We study possibilities of formation of the topped hadrons, the [Formula: see text], [Formula: see text], tqq, ttq and ttt bound systems. We assume that the inverse of binding energy is the parameter of the formation time of the bound system and take the ratio Γtotal/EB as a criterion for the formation of these hadrons, where EB and Γtotal are a binding energy and a total decay width of a topped system respectively. We take into account the binding force caused by the Higgs scalar exchange as well as the one-gluon exchange. It is shown that there is no possibility of forming the single top quark hadrons before the top quark decay. In the standard model, where only one Higgs doublet contributes, among the topped hadrons only toponium [Formula: see text] and the three-top-quark baryon Ωttt with the top quark mass less than 140 GeV and 130 GeV have a possibility of forming the bound states before their decay. In the case of the two-Higgs-doublet model we show that there is a possibility of forming the topped hadrons, toponium, Ξtt and Ωttt for the larger top quark mass if the ratio of vacuum expectation values of two Higgs scalars is large near to the unitarity bound.

ONE-LOOP RADIATIVE CORRECTIONS TO A HEAVY TOP DECAY IN THE STANDARD MODEL

1991 ◽  
Vol 06 (27) ◽  
pp. 4925-4948 ◽  
Author(s):  
JIANG LIU ◽  
YORK-PENG YAO
Keyword(s):  
Top Quark ◽  
Asymmetry Parameter ◽  
Partial Width ◽  
Angular Distributions ◽  
Radiative Corrections ◽  
Inclusive Process ◽  
The Standard Model ◽  
Top Quark Decay ◽  
Quark Decay ◽  
Exclusive Or

We study one-loop radiative corrections to the top-quark decay: t→bW. For a heavy top (i.e. mt≳100 GeV ), simple analytic formulas are derived. For the inclusive process, t→bW+X due to QCD, cancellations of infrared and mass singularities are shown explicitly. The final result agrees with an earlier calculation in the literature, and is an 8% reduction in the partial width for αs=0.1. Also, leading terms of the electroweak corrections are shown to be proportional to an enhancement factor [Formula: see text]. Their effect is about 1-3%. We also study the angular distributions of the leptons from the subsequent exclusive (or semi-inclusive) W decay. An asymmetry parameter which measures the polarizations of the W is introduced. We find that it is sensitive to the QCD corrections especially in the vicinity of [Formula: see text].

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