scholarly journals TOP PAIR PRODUCTION III: TESTING THE STANDARD MODEL IN TOP QUARK DECAYS

2007 ◽  
Author(s):  
D. WICKE ◽  
Keyword(s):  
Standard Model ◽  
Pair Production ◽  
Top Quark ◽  
Quark Decays ◽  
The Standard Model ◽  
Top Pair Production

Probing space–time noncommutativity in the top quark pair production at e+e- collider

2014 ◽  
Vol 29 (27) ◽  
pp. 1450156 ◽  
Author(s):  
Ravi S. Manohar ◽  
J. Selvaganapathy ◽  
Prasanta Kumar Das
Keyword(s):  
Standard Model ◽  
Pair Production ◽  
Top Quark ◽  
Linear Collider ◽  
Standard Model Prediction ◽  
Orientation Angle ◽  
Laboratory Frame ◽  
The Standard Model ◽  
Rapidity Distributions ◽  
Azimuthal Asymmetries

The forward–backward asymmetry observed in the top quark pair production at the Fermilab Tevatron points toward the existence of beyond the standard model physics. We have studied the top quark pair production [Formula: see text] in the TeV energy electron–positron linear collider to the leading order of the noncommutative parameter Θμν in the noncommutative standard model. We have made a detailed laboratory frame analysis of the time-averaged cross-section, polar, azimuthal angular distributions, transverse momentum and rapidity distributions, polar (forward–backward) and azimuthal asymmetries of the top-quark pair production in the presence of earth's rotation. We investigated their dependence on the orientation angle of the noncommutative vector η and the noncommutative scale Λ and found that those deviates from the standard model distributions significantly. The azimuthal distribution which is flat in the standard model deviates largely for η = π/2 and Λ = 700 GeV at the fixed machine energy E com = 1000 GeV . We found that the polar distribution deviates largely from the standard model distribution for η = π/2 and Λ = 500 GeV . The azimuthal asymmetry Aϕ which is zero in the standard model can be as large as 4% for Λ = 500 GeV and η = π/2 at the fixed machine energy E com = 1000 GeV . Assuming that the future TeV linear collider will observe Aϕ = ±0.01 we find Λ≤750(860) GeV corresponding to η = π/2. Similarly, corresponding to polar asymmetry A FBz = 0.5078 (which deviates from the standard model prediction by 1%), we find Λ≤760 GeV at the fixed machine energy E com = 1000 GeV for η = π/2.

scholarly journals EFFECTS OF NONSTANDARD INTERACTIONS FOR THE ENERGY SPECTRUM OF SECONDARY LEPTONS IN $e^+ e^-\to t\bar t$

1999 ◽  
Vol 14 (08) ◽  
pp. 1261-1281 ◽  
Author(s):  
LONGIN BRZEZIŃSKI ◽  
BOHDAN GRZADKOWSKI ◽  
ZENRŌ HIOKI
Keyword(s):  
Energy Spectrum ◽  
Standard Model ◽  
Pair Production ◽  
Top Quark ◽  
High Energy ◽  
Parameter Determination ◽  
Beyond The Standard Model ◽  
Energy Correlation ◽  
Optimal Method ◽  
The Standard Model

The process of top-quark pair production followed by semileptonic decays at future high-energy e+ e- linear colliders is investigated as a possible test of physics beyond the Standard Model. Assuming the most general nonstandard forms for [Formula: see text], [Formula: see text] and Wtb couplings, the energy spectrum of the single lepton ℓ± and the energy correlation of ℓ+ and ℓ- emerging from the process [Formula: see text] are calculated. Expected precision of the nonstandard-parameter determination is estimated adopting the recently-proposed optimal method.

scholarly journals Indirect $$ \mathcal{CP} $$ probes of the Higgs-top-quark interaction: current LHC constraints and future opportunities

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Henning Bahl ◽  
Philip Bechtle ◽  
Sven Heinemeyer ◽  
Judith Katzy ◽  
Tobias Klingl ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Top Quark ◽  
Decay Channel ◽  
New Physics ◽  
Current Data ◽  
Quark Interaction ◽  
The Standard Model ◽  
Vector Bosons ◽  
Selection Of

Abstract The $$ \mathcal{CP} $$ CP structure of the Higgs boson in its coupling to the particles of the Standard Model is amongst the most important Higgs boson properties which have not yet been constrained with high precision. In this study, all relevant inclusive and differential Higgs boson measurements from the ATLAS and CMS experiments are used to constrain the $$ \mathcal{CP} $$ CP -nature of the top-Yukawa interaction. The model dependence of the constraints is studied by successively allowing for new physics contributions to the couplings of the Higgs boson to massive vector bosons, to photons, and to gluons. In the most general case, we find that the current data still permits a significant $$ \mathcal{CP} $$ CP -odd component in the top-Yukawa coupling. Furthermore, we explore the prospects to further constrain the $$ \mathcal{CP} $$ CP properties of this coupling with future LHC data by determining tH production rates independently from possible accompanying variations of the $$ t\overline{t}H $$ t t ¯ H rate. This is achieved via a careful selection of discriminating observables. At the HL-LHC, we find that evidence for tH production at the Standard Model rate can be achieved in the Higgs to diphoton decay channel alone.

scholarly journals A CRITICAL LOOK AT PRECISION ELECTROWEAK DATA AT HIGH ENERGY—A HINT FOR PHYSICS BEYOND THE STANDARD MODEL?

1994 ◽  
Vol 09 (35) ◽  
pp. 3301-3312
Author(s):  
A. GURTU
Keyword(s):  
Standard Model ◽  
Pair Production ◽  
High Energy ◽  
Recent Measurement ◽  
Beyond The Standard Model ◽  
Full Data ◽  
Text Production ◽  
Basic Framework ◽  
The Standard Model ◽  
Precision Electroweak Data

High energy electroweak data, including the recent measurement of M top is analyzed within the basic framework of the standard model. While the experimentally measured value of [Formula: see text] implies a low value of M top , the rest of the data demands a much higher value. Estimates of M Higgs within the SM framework including and excluding this Rb measurement are given. Next this discrepancy is expressed in terms of a new parameter, [Formula: see text], the excess[Formula: see text] production compared to that expected from a SM fit. This parameter is determined to be (9.4 to 12.8) ± 5.0 MeV, implying an excess of over 10 000 [Formula: see text] events in each LEP experiment after the 1993 data is fully analyzed. The origin of these events could be non-minimal Higgs pair production which should be thoroughly searched for in the full data sample of ~2×106 events per LEP experiment. Unless this discrepancy eventually turns out to be a fluctuation one may be witnessing at LEP the advent of physics beyond the standard model.

scholarly journals Mass Reconstruction of MSSM Higgs Boson

2019 ◽  
Vol 64 (8) ◽  
pp. 714
Author(s):  
T. V. Obikhod ◽  
I. A. Petrenko
Keyword(s):  
Experimental Data ◽  
Higgs Boson ◽  
Standard Model ◽  
Top Quark ◽  
Computer Programs ◽  
Higgs Bosons ◽  
Associated Production ◽  
The Standard Model ◽  
The Masses ◽  
Mass Reconstruction

The problems of the Standard Model, as well as questions related to Higgs boson properties led to the need to model the ttH associated production and the Higgs boson decay to a top quark pair within the MSSM model. With the help of computer programs MadGraph, Pythia, and Delphes and using the latest kinematic cuts taken from experimental data obtained at the LHC, we have predicted the masses of MSSM Higgs bosons, A and H.

Electroweak Interactions and W, Z Boson Properties

2020 ◽  
Author(s):  
Maarten Boonekamp ◽  
Matthias Schott
Keyword(s):  
Standard Model ◽  
Weak Interaction ◽  
Top Quark ◽  
Quantum Electrodynamics ◽  
Weak Interactions ◽  
Higgs Field ◽  
Nuclear Research ◽  
Strong Interactions ◽  
Weak Boson ◽  
The Standard Model

With the huge success of quantum electrodynamics (QED) to describe electromagnetic interactions in nature, several attempts have been made to extend the concept of gauge theories to the other known fundamental interactions. It was realized in the late 1960s that electromagnetic and weak interactions can be described by a single unified gauge theory. In addition to the photon, the single mediator of the electromagnetic interaction, this theory predicted new, heavy particles responsible for the weak interaction, namely the W and the Z bosons. A scalar field, the Higgs field, was introduced to generate their mass. The discovery of the mediators of the weak interaction in 1983, at the European Center for Nuclear Research (CERN), marked a breakthrough in fundamental physics and opened the door to more precise tests of the Standard Model. Subsequent measurements of the weak boson properties allowed the mass of the top quark and of the Higgs Boson to be predicted before their discovery. Nowadays, these measurements are used to further probe the consistency of the Standard Model, and to place constrains on theories attempting to answer still open questions in physics, such as the presence of dark matter in the universe or unification of the electroweak and strong interactions with gravity.

Sign in / Sign up

Export Citation Format

Share Document