scholarly journals Interplay between new physics in one-loop Higgs couplings and the top-quark Yukawa coupling

2013 ◽  
Vol 88 (3) ◽  
Author(s):  
Xiao-Gang He ◽  
Yong Tang ◽  
German Valencia
Keyword(s):  
Yukawa Coupling ◽  
Top Quark ◽  
New Physics

scholarly journals Exact one-loop running couplings in the standard model

2008 ◽  
Vol 86 (9) ◽  
pp. 1067-1070 ◽  
Author(s):  
F A Chishtie ◽  
M D Lepage ◽  
D GC McKeon ◽  
T G Steele ◽  
I Zakout
Keyword(s):  
Standard Model ◽  
Yukawa Coupling ◽  
Top Quark ◽  
Higgs Mass ◽  
Gauge Coupling ◽  
New Physics ◽  
Energy Scale ◽  
Scalar Coupling ◽  
Upper And Lower Bounds ◽  
The Standard Model

Taking the dominant couplings in the standard model to be the quartic scalar coupling, the Yukawa coupling of the top quark, and the SU(3) gauge coupling, we consider their associated running couplings to one-loop order. Despite the nonlinear nature of the differential equations governing these functions, we show that they can be solved exactly. The nature of these solutions is discussed and their singularity structure is examined. It is shown that for a sufficiently small Higgs mass, the quartic scalar coupling decreases with increasing energy scale and becomes negative, indicative of vacuum instability. This behavior changes for a Higgs mass greater than 168 GeV, beyond which this couplant increases with increasing energy scales and becomes singular prior to the ultraviolet pole of the Yukawa coupling. Upper and lower bounds on the Higgs mass corresponding to new physics at the TeV scale are obtained and compare favourably with the numerical results of the one-loop and two-loop analyses with inclusion of electroweak couplings.PACS Nos.: 11.10.Hi, 14.80.Bn

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 Infrared renormalons in collider processes

2021 ◽  
Author(s):  
Silvia Ferrario Ravasio
Keyword(s):  
Top Quark ◽  
Particle Physics ◽  
Theoretical Calculations ◽  
Accurate Determination ◽  
New Physics ◽  
Operator Product ◽  
Power Correction ◽  
Collider Phenomenology ◽  
Power Corrections ◽  
Decay Products

AbstractPrecise theoretical predictions are a key ingredient for an accurate determination of the structure of the Lagrangian of particle physics, including its free parameters, which summarizes our understanding of the fundamental interactions among particles. Furthermore, due to the absence of clear new-physics signals, precise theoretical calculations are required to pin down possible subtle deviations from the Standard Model predictions. The error associated with such calculations must be scrutinized, as non-perturbative power corrections, dubbed infrared renormalons, can limit the ultimate precision of truncated perturbative expansions in quantum chromodynamics. In this review, we focus on linear power corrections that can arise in certain kinematic distributions relevant for collider phenomenology where an operator product expansion is missing, e.g. those obtained from the top-quark decay products, shape observables and the transverse momentum of massive gauge bosons. Only the last one is found to be free from such corrections, while the mass of the system comprising the top decay products has a larger power correction if the perturbative expansion is expressed in terms of a short-distance mass instead of the pole mass. A proper modelization of non-perturbative corrections is crucial in the context of shape observables to obtain reliable strong coupling constant extractions.

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 A set of top quark spin correlation and polarization observables for the LHC: Standard Model predictions and new physics contributions

2015 ◽  
Vol 2015 (12) ◽  
pp. 1-36 ◽  
Author(s):  
Werner Bernreuther ◽  
Dennis Heisler ◽  
Zong-Guo Si
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
Spin Correlation ◽  
New Physics ◽  
Quark Spin ◽  
Model Predictions ◽  
Polarization Observables

scholarly journals Probing new physics from top quark FCNC processes at linear colliders: a mini review

2005 ◽  
Vol 316 (2) ◽  
pp. 529-539 ◽  
Author(s):  
Jin Min Yang
Keyword(s):  
Top Quark ◽  
New Physics ◽  
Linear Colliders

scholarly journals tt̄H Coupling Measurement with the ATLAS Detector at the LHC

2018 ◽  
Vol 182 ◽  
pp. 02052
Author(s):  
Asma Hadef
Keyword(s):  
Higgs Boson ◽  
Cross Sections ◽  
Top Quark ◽  
High Energy Physics ◽  
Center Of Mass ◽  
High Energy ◽  
New Physics ◽  
Decay Modes ◽  
Center Of Mass Energy ◽  
Higgs Decay

The Higgs boson was discovered on the 4th of July 2012 with a mass around 125 GeV by ATLAS and CMS experiments at LHC. Determining the Higgs properties (production and decay modes, couplings,...) is an important part of the high-energy physics programme in this decade. A search for the Higgs boson production in association with a top quark pair (tt̄H) at ATLAS [1] is summarized in this paper at an unexplored center-of-mass energy of 13 TeV, which could allow a first direct measurement of the top quark Yukawa coupling and could reveal new physics. The tt̄H analysis in ATLAS is divided into 3 channels according to the Higgs decay modes: H → Hadrons, H → Leptons and H → Photons. The best-fit value of the ratio of observed and Standard Model cross sections of tt̄H production process, using 2015-2016 data and combining all tt̄H final states, is 1:8±0:7, corresponds to 2:8σ (1:8σ) observed (expected) significance.

scholarly journals Top quark Yukawa couplings and new physics

2001 ◽  
Author(s):  
S. Dawson
Keyword(s):  
Top Quark ◽  
New Physics ◽  
Yukawa Couplings

Top quark at the upgraded Tevatron to prove new physics

1998 ◽  
Author(s):  
Jin Min Yang ◽  
A. Datta ◽  
M. Hosch ◽  
C. S. Li ◽  
R. J. Oakes ◽  
...  
Keyword(s):  
Top Quark ◽  
New Physics

scholarly journals Phenomenology of a nonstandard top quark Yukawa coupling

1994 ◽  
Vol 50 (11) ◽  
pp. 7042-7047 ◽  
Author(s):  
X. Zhang ◽  
S. K. Lee ◽  
K. Whisnant ◽  
B.-L. Young
Keyword(s):  
Yukawa Coupling ◽  
Top Quark
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