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 HIGGS MASS IN THE STANDARD MODEL FROM COUPLING CONSTANT REDUCTION

2002 ◽  
Vol 17 (03) ◽  
pp. 335-346 ◽  
Author(s):  
B. ANANTHANARAYAN ◽  
J. PASUPATHY
Keyword(s):  
Renormalization Group ◽  
Standard Model ◽  
Top Quark ◽  
Higgs Mass ◽  
Gauge Coupling ◽  
Renormalization Scale ◽  
Coupling Constant ◽  
Top Quark Mass ◽  
The Standard Model ◽  
The One

Plausible interrelations between parameters of the standard model are studied. The empirical value of the top quark mass, when used in the renormalization group equations, suggests that the ratio of the color SU(3) gauge coupling g3, and the top coupling gt is independent of the renormalization scale. On the other hand, the variety of top-condensate models suggests that the Higgs self-coupling λ is proportional to [Formula: see text]. Invoking the requirement that the ratio [Formula: see text] is independent of the renormalization scale t, fixes the Higgs mass. The pole mass of the Higgs (which differs from the renormalization group mass by a few percent) is found to be ~ 154 GeV for the one-loop equations and ~ 148 GeV for the two-loop equations.

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 CALCULATION OF HIGGS MASS IN THE STANDARD MODEL

2000 ◽  
Vol 15 (26) ◽  
pp. 1605-1610 ◽  
Author(s):  
J. PASUPATHY
Keyword(s):  
Standard Model ◽  
Yukawa Coupling ◽  
Higgs Mass ◽  
Renormalization Scale ◽  
The Standard Model ◽  
Gauge Couplings ◽  
Top Mass

The assumption that the ratio of the Higgs self-coupling to the square of its Yukawa coupling to the top is (almost) independent of the renormalization scale fixes the Higgs mass within narrow limits at m H =160 GeV using only the values of gauge couplings and top mass.

scholarly journals PROBING NEW PHYSICS FROM TOP QUARK FCNC PROCESS AT LHC: A MINI REVIEW

2008 ◽  
Vol 23 (21) ◽  
pp. 3343-3347 ◽  
Author(s):  
JIN MIN YANG
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
New Physics ◽  
Supersymmetric Model ◽  
The Standard Model ◽  
Minimal Supersymmetric Model

Since the top quark FCNC processes are extremely supressed in the Standard Model (SM) but could be greatly enhanced in some new physics models, they could serve as a smoking gun for new physics hunting at the LHC. In this brief review we summarize the new physics predictions for various top quark FCNC processes at the LHC by focusing on two typical models: the minimal supersymmetric model (MSSM) and the topcolor-assisted technicolor (TC2) model. The conclusion is: (1) Both new physics models can greatly enhance the SM predictions by several orders; (2) The TC2 model allows for largest enhancement, and for each channel the maximal prediction is much larger than in the MSSM; (3) Compared with the 3σ sensitivity at the LHC, only a couple of channels are accessible for the MSSM while most channles are accesible for the TC2 model.

scholarly journals Electroweak symmetry non-restoration from dark matter

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Oleksii Matsedonskyi ◽  
James Unwin ◽  
Qingyun Wang
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Higgs Mass ◽  
Direct Detection ◽  
Higgs Doublet ◽  
New Physics ◽  
Electroweak Symmetry ◽  
The Standard Model ◽  
New States ◽  
Potential Remedy

Abstract Restoration of the electroweak symmetry at temperatures around the Higgs mass is linked to tight phenomenological constraints on many baryogenesis scenarios. A potential remedy can be found in mechanisms of electroweak symmetry non-restoration (SNR), in which symmetry breaking is extended to higher temperatures due to new states with couplings to the Standard Model. Here we show that, in the presence of a second Higgs doublet, SNR can be realized with only a handful of new fermions which can be identified as viable dark matter candidates consistent with all current observational constraints. The competing requirements on this class of models allow for SNR at temperatures up to ∼TeV, and imply the presence of sub-TeV new physics with sizable interactions with the Standard Model. As a result this scenario is highly testable with signals in reach of next-generation collider and dark matter direct detection experiments.

scholarly journals Probing Higgs boson CP properties with tt̄H at the LHC and the 100 TeV pp collider

2015 ◽  
Vol 30 (25) ◽  
pp. 1550156 ◽  
Author(s):  
Xiao-Gang He ◽  
Guan-Nan Li ◽  
Ya-Juan Zheng
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Top Quark ◽  
New Physics ◽  
Final States ◽  
Discrimination Power ◽  
Text Production ◽  
Wide Range ◽  
The Standard Model ◽  
The Ideal

The Higgs boson [Formula: see text] has the largest coupling to the top quark [Formula: see text] among the standard model (SM) fermions. This is one of the ideal places to investigate new physics beyond SM. In this work, we study the potential of determining Higgs boson [Formula: see text] properties at the LHC and future 33 TeV and 100 TeV [Formula: see text] colliders by analyzing various operators formed from final states variables in [Formula: see text] production. The discrimination power from SM coupling is obtained with Higgs boson reconstructed from [Formula: see text] and [Formula: see text]. We find that [Formula: see text] process can provide more than [Formula: see text] discrimination power with [Formula: see text] integrated luminosity in a wide range of allowed Higgs to top couplings for the LHC, the 33 TeV and 100 TeV colliders. For [Formula: see text] the discrimination power will be below [Formula: see text] at the LHC, while for 33 TeV and 100 TeV colliders, more than [Formula: see text] sensitivity can be reached.

scholarly journals Lorentz-violating effects on pair production of W bosons in photon collisions

2014 ◽  
Vol 29 (31) ◽  
pp. 1450180 ◽  
Author(s):  
J. I. Aranda ◽  
F. Ramírez-Zavaleta ◽  
F. J. Tlachino ◽  
J. J. Toscano ◽  
E. S. Tututi
Keyword(s):  
Standard Model ◽  
Polarization State ◽  
New Physics ◽  
Lorentz Symmetry ◽  
Energy Scale ◽  
Lagrangian Model ◽  
Standard Model Extension ◽  
Symmetry Violation ◽  
Model Extension ◽  
The Standard Model

We examine Lorentz-violating effects that could appear through deviations of the Standard Model gauge couplings WWγ, WWγγ, Zγγ and γγγ. These new physics effects are explored on the γγ→WW reaction at possible future Linear Colliders. In particular, the associated helicity amplitudes are computed in the context of the Standard Model Extension (which is a model that includes Lorentz violation) and the Effective Lagrangian Model (which incorporates new physics effects that respect Lorentz symmetry). We perform an exhaustive study of the polarized differential cross-sections to stand out effects related to Lorentz symmetry violation, where it is evidenced that the effects of Lorentz symmetry violation are more sensitive to the presence of the e background field. We found that for the (±, ±, (L, T+T, L)) polarization state, only Standard Model Extension contributes at the lowest order. For this polarization state, with an integrated luminosity assumed to be 103 fb -1, we estimated up to 1 event for a Lorentz-violating energy scale of 44 TeV.

scholarly journals Towards a Higgs mass determination in asymptotically safe gravity with a dark portal

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Astrid Eichhorn ◽  
Martin Pauly ◽  
Shouryya Ray
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
Quark Mass ◽  
Higgs Mass ◽  
Beyond The Standard Model ◽  
Top Quark Mass ◽  
Dark Sector ◽  
Central Value ◽  
The Standard Model ◽  
Higgs Portal

Abstract There are indications that an asymptotically safe UV completion of the Standard Model with gravity could constrain the Higgs self-coupling, resulting in a prediction of the Higgs mass close to the vacuum stability bound in the Standard Model. The predicted value depends on the top quark mass and comes out somewhat higher than the experimental value if the current central value for the top quark mass is assumed. Beyond the Standard Model, the predicted value also depends on dark fields coupled through a Higgs portal. Here we study the Higgs self-coupling in a toy model of the Standard Model with quantum gravity that we extend by a dark scalar and fermion. Within the approximations used in [1], there is a single free parameter in the asymptotically safe dark sector, as a function of which the predicted (toy model) Higgs mass can be lowered due to mixing effects if the dark sector undergoes spontaneous symmetry breaking.

scholarly journals SEARCHES FOR NEW PARTICLES

2002 ◽  
Vol 17 (23) ◽  
pp. 3336-3351 ◽  
Author(s):  
GAIL G. HANSON
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
New Physics ◽  
Higgs Bosons ◽  
Standard Model Higgs Boson ◽  
The Past ◽  
Flavor Changing ◽  
The Standard Model ◽  
The Status ◽  
New Particles

The status of searches for new particles and new physics during the past year at the Fermilab Tevatron, at HERA and at LEP is summarized. A discussion of the hints for the Standard Model Higgs boson from LEP2 data is presented. Searches for non-Standard Model Higgs bosons are also described. Many searches have been carried out for the particles predicted by supersymmetry theories, and a sampling of these is given. There have also been searches for flavor changing neutral currents in the interactions of the top quark. In addition, searches for excited leptons, leptoquarks and technicolor are summarized.

scholarly journals Searching for new physics in semi-leptonic baryon decays

2017 ◽  
Vol 32 (08) ◽  
pp. 1750043 ◽  
Author(s):  
E. Di Salvo ◽  
Z. J. Ajaltouni
Keyword(s):  
Standard Model ◽  
Decay Width ◽  
Form Factors ◽  
New Physics ◽  
Scalar Coupling ◽  
Partial Decay Width ◽  
Beyond The Standard Model ◽  
Leptonic Decays ◽  
The Standard Model ◽  
Pseudo Scalar

We propose two different and complementary observables for singling out possible signals of physics beyond the Standard Model (SM) in the semi-leptonic decays [Formula: see text], both with the [Formula: see text] lepton and with a light lepton. The two observables are the partial decay width and a T-odd asymmetry, whose respective sensitivities to scalar and/or pseudo-scalar coupling are calculated as functions of the parameters characterizing new physics (NP). Two different form factors are used. Three particular cases are discussed and analyzed in detail.

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