scholarly journals Next-to-next-to-leading orderO(α2αs2)results for top quark pair production in photon-photon collisions: The one-loop squared contributions

2006 ◽  
Vol 74 (9) ◽  
Author(s):  
J. G. Körner ◽  
Z. Merebashvili ◽  
M. Rogal
Keyword(s):  
Pair Production ◽  
Top Quark ◽  
The One

scholarly journals Top quark pair production near threshold: single/double distributions and mass determination

2020 ◽  
Vol 2020 (6) ◽  
Author(s):  
Wan-Li Ju ◽  
Guoxing Wang ◽  
Xing Wang ◽  
Xiaofeng Xu ◽  
Yongqi Xu ◽  
...  
Keyword(s):  
Pair Production ◽  
Top Quark ◽  
Mass Determination ◽  
Near Threshold

scholarly journals Search for pair production of third-generation scalar leptoquarks decaying into a top quark and a τ-lepton in pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
◽  
G. Aad ◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Pair Production ◽  
Top Quark ◽  
Production Cross ◽  
Branching Fraction ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Third Generation ◽  
Final State ◽  
Generation Scalar ◽  
Scalar Leptoquarks

Abstract A search for pair production of third-generation scalar leptoquarks decaying into a top quark and a τ-lepton is presented. The search is based on a dataset of pp collisions at $$ \sqrt{s} $$ s = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1. Events are selected if they have one light lepton (electron or muon) and at least one hadronically decaying τ -lepton, or at least two light leptons. In addition, two or more jets, at least one of which must be identified as containing b-hadrons, are required. Six final states, defined by the multiplicity and flavour of lepton candidates, are considered in the analysis. Each of them is split into multiple event categories to simultaneously search for the signal and constrain several leading backgrounds. The signal-rich event categories require at least one hadronically decaying τ-lepton candidate and exploit the presence of energetic final-state objects, which is characteristic of signal events. No significant excess above the Standard Model expectation is observed in any of the considered event categories, and 95% CL upper limits are set on the production cross section as a function of the leptoquark mass, for different assumptions about the branching fractions into tτ and bν. Scalar leptoquarks decaying exclusively into tτ are excluded up to masses of 1.43 TeV while, for a branching fraction of 50% into tτ, the lower mass limit is 1.22 TeV.

scholarly journals Optimising top-quark threshold scan at CLIC using genetic algorithm

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
K. Nowak ◽  
A.F. Żarnecki
Keyword(s):  
Genetic Algorithm ◽  
Pair Production ◽  
Top Quark ◽  
Quark Mass ◽  
Mass Measurement ◽  
Production Cross ◽  
Model Parameters ◽  
Top Quark Mass ◽  
Systematic Uncertainties ◽  
Pair Production Cross Section

Abstract One of the important goals at the future e+e− colliders is to measure the top-quark mass and width in a scan of the pair production threshold. However, the shape of the pair-production cross section at the threshold depends also on other model parameters, as the top Yukawa coupling, and the measurement is a subject to many systematic uncertainties. Presented in this work is the study of the top-quark mass determination from the threshold scan at CLIC. The most general approach is used with all relevant model parameters and selected systematic uncertainties included in the fit procedure. Expected constraints from other measurements are also taken into account. It is demonstrated that the top-quark mass can be extracted with precision of the order of 30 to 40 MeV, including considered systematic uncertainties, already for 100 fb−1 of data collected at the threshold. Additional improvement is possible, if the running scenario is optimised. With the optimisation procedure based on the genetic algorithm the statistical uncertainty of the mass measurement can be reduced by about 20%. Influence of the collider luminosity spectra on the expected precision of the measurement is also studied.

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 Full top quark mass dependence in Higgs boson pair production at NLO

2016 ◽  
Vol 2016 (10) ◽  
Author(s):  
S. Borowka ◽  
N. Greiner ◽  
G. Heinrich ◽  
S.P. Jones ◽  
M. Kerner ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Pair Production ◽  
Top Quark ◽  
Quark Mass ◽  
Mass Dependence ◽  
Top Quark Mass ◽  
Boson Pair ◽  
Boson Pair Production ◽  
Quark Mass Dependence

scholarly journals Spin effects in hadronic top quark pair production

2007 ◽  
Author(s):  
Werner Bernreuther ◽  
Michael Fucker ◽  
Zong-Guo Si
Keyword(s):  
Pair Production ◽  
Top Quark ◽  
Spin Effects
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