scholarly journals Mixed EW-QCD leading fermionic three-loop corrections at $$ \mathcal{O} $$(αsα2) to electroweak precision observables

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Lisong Chen ◽  
Ayres Freitas
Keyword(s):  
Top Quark ◽  
Z Boson ◽  
W Boson ◽  
Boson Mass ◽  
Top Quark Mass ◽  
Weak Mixing Angle ◽  
Mixing Angle ◽  
The Standard Model ◽  
Precision Observables ◽  
Electroweak Precision

Abstract Measurements of electroweak precision observables at future electron-position colliders, such as the CEPC, FCC-ee, and ILC, will be sensitive to physics at multi-TeV scales. To achieve this sensitivity, precise predictions for the Standard Model expectations of these observables are needed, including corrections at the three- and four-loop level. In this article, results are presented for the calculation of a subset of three-loop mixed electroweak-QCD corrections, stemming from diagrams with a gluon exchange and two closed fermion loops. The numerical impact of these corrections is illustrated for a number of applications: the prediction of the W-boson mass from the Fermi constant, the effective weak mixing angle, and the partial and total widths of the Z boson. Two alternative renormalization schemes for the top-quark mass are considered, on-shell and $$ \overline{\mathrm{MS}} $$ MS ¯ .

scholarly journals Theory requirements for SM Higgs and EW precision physics at the FCC-ee

2021 ◽  
Vol 136 (9) ◽  
Author(s):  
S. Heinemeyer ◽  
S. Jadach ◽  
J. Reuter
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
High Precision ◽  
Boson Mass ◽  
Experimental Measurements ◽  
Mixing Angle ◽  
The Standard Model ◽  
The Status ◽  
Precision Observables ◽  
Electroweak Precision

AbstractHigh-precision experimental measurements of the properties of the Higgs boson at $$\sim 125$$ ∼ 125  GeV as well as electroweak precision observables such as the W-boson mass or the effective weak leptonic mixing angle are expected at future $$e^+e^-$$ e + e - colliders such as the FCC-ee. This high anticipated precision has to be matched with theory predictions for the measured quantities at the same level of accuracy. We briefly summarize the status of these predictions within the standard model and of the tools that are used for their determination. We outline how the theory predictions will have to be improved in order to reach the required accuracy, and also comment on the simulation frameworks for the Higgs and EW precision program.

scholarly journals SUPERSYMMETRY AND UNIFICATION: HEAVY TOP WAS THE KEY

2012 ◽  
Vol 13 ◽  
pp. 182-190 ◽  
Author(s):  
GORAN SENJANOVIĆ
Keyword(s):  
Top Quark ◽  
Quark Mass ◽  
Correct Prediction ◽  
Top Quark Mass ◽  
Weak Mixing Angle ◽  
Mixing Angle ◽  
Grand Unified Theories ◽  
The Standard Model ◽  
Unified Theories ◽  
History Of

I review the history of the unification of gauge couplings of the Standard Model. I start by recalling the history of the most important prediction of low-energy supersymmetry: the correct prediction of the weak mixing angle tied to the prediction of a large top quark mass. I then turn to the discussion of the present day situation of the minimal supersymmetric Grand Unified Theories based on SU(5) and SO(10) groups. For the sake of completeness I also summarize the problems and possible solution of the minimal ordinary SU(5).

TOP AND HIGGS HUNTING VIA Mw AND Γz

1991 ◽  
Vol 06 (23) ◽  
pp. 2129-2135 ◽  
Author(s):  
ZENRŌ HIOKI
Keyword(s):  
Top Quark ◽  
Z Boson ◽  
W Boson ◽  
Parton Model ◽  
Boson Mass ◽  
Top Quark Mass ◽  
Total Decay Width ◽  
Model Calculations ◽  
Hadron Physics ◽  
Electroweak Radiative Corrections

Virtual top and Higgs effects are studied through the electroweak radiative corrections to the W boson mass, MW, and the total decay-width of the Z boson, ΓZ, by using the data [Formula: see text], [Formula: see text] and [Formula: see text]. Carrying out the χ2 fit in the framework of the standard electroweak theory, constraints are derived on the top-quark mass, mt, and the Higgs–boson mass, mϕ, which are almost free from the complicated hadron physics like parton model calculations. For example, [Formula: see text] for mϕ = 100 GeV (at 1σ level) while mϕ ≲ 680 GeV if mt ≤ 110 GeV and mϕ ≳ 280 GeV if mt ≥ 190 GeV . It is also studied how precise measurements of MW at LEP II improve these constraints.

CANCELLATION OF ULTRAVIOLET DIVERGENCES IN THE SU(2)L×U(1) ELECTROWEAK MODEL

1989 ◽  
Vol 04 (28) ◽  
pp. 2733-2738 ◽  
Author(s):  
ROGER DECKER ◽  
JEAN PESTIEAU
Keyword(s):  
Top Quark ◽  
Z Boson ◽  
Charged Lepton ◽  
W Boson ◽  
Boson Mass ◽  
Three Generations ◽  
Electroweak Model

We assume that, in the SU(2)L×U(1) model, ultraviolet divergences of the charged lepton self-masses are zero. We predict the top and Higgs masses in the vicinity of the Z-boson mass. Our assumption holds only if there are no more than three generations of quarks and leptons and if quarks and leptons, except for the top quark, have negligible masses compared to the W-boson mass.

scholarly journals THE MINIMAL SUPERSYMMETRIC STANDARD MODEL AND PRECISION OF W-BOSON MASS AND TOP QUARK MASS

1998 ◽  
Vol 13 (32) ◽  
pp. 2613-2620 ◽  
Author(s):  
KYUNGSIK KANG ◽  
SIN KYU KANG
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Top Quark ◽  
Quark Mass ◽  
W Boson ◽  
Boson Mass ◽  
Higgs Boson Mass ◽  
Top Quark Mass ◽  
Present Value ◽  
Central Values

We argue that the present value and accuracy of MW and mt measurements tend to favor the MSSM, provided that the central values of MW and mt stay at the current values, over the SM. By speculating that a precision of order 40 MeV and 3 GeV respectively for MW and mt will be achieved at LEP2 and Tevatron, we show that the prospect for the MSSM will be further enhanced as long as the central values of MW and mt do not increase below the present values. In addition, we discuss how this scenario can constrain the Higgs boson mass and distinguish the Higgs boson of the MSSM type from that of the SM.

scholarly journals CONSTRAINING NEW MODELS WITH PRECISION ELECTROWEAK DATA

2006 ◽  
Vol 21 (19n20) ◽  
pp. 4045-4070 ◽  
Author(s):  
MU-CHUN CHEN ◽  
SALLY DAWSON ◽  
TADAS KRUPOVNICKAS
Keyword(s):  
Top Quark ◽  
New Physics ◽  
Tree Level ◽  
Symmetric Model ◽  
Top Quark Mass ◽  
Precision Data ◽  
The Standard Model ◽  
The One ◽  
Electroweak Precision ◽  
Electroweak Precision Data

Electroweak precision data have been extensively used to constrain models containing physics beyond that of the Standard Model (SM). When the model contains Higgs scalars in representations other than singlets or doublets, and hence ρ≠1 at tree-level, a correct renormalization scheme requires more inputs than the three commonly used for the SM case. In such cases, the one-loop electroweak results cannot be split into a SM contribution plus a piece which vanishes as the scale of new physics becomes much larger than MW. We illustrate our results by presenting the dependence of MW on the top-quark mass in a model with a Higgs triplet and in the SU (2)L × SU (2)R left–right symmetric model. In these models, the allowed range for the lightest neutral Higgs mass can be as large as a few TeV.

CONSTRAINTS ON THE SU(5)C × SU(2)L × U(1)′ MODEL FROM LEP DATA

1999 ◽  
Vol 14 (07) ◽  
pp. 1049-1060 ◽  
Author(s):  
SASWATI SARKAR ◽  
ASIM K. RAY ◽  
UTPAL SARKAR
Keyword(s):  
Lower Bound ◽  
Standard Model ◽  
Gauge Boson ◽  
Z Boson ◽  
Boson Mass ◽  
Precision Measurements ◽  
Tree Level ◽  
Mixing Angle ◽  
Neutral Gauge Boson ◽  
The Standard Model

We have determined constraints on the SU (5)C × SU (2)L × U (1)′ model in terms of the extra mixing angle ϕ in the neutral gauge boson sector and ΔρM, the deviation of the Standard Model ρ parameter from unity at the tree level, using the recent precision measurements at LEP on electroweak parameters at the Z peak. The lower bound of the extra Z′ boson mass has also been determined.

THE Z BOSON, THE TOP QUARK, AND NON-MINIMAL HIGGS BOSONS

1990 ◽  
Vol 05 (24) ◽  
pp. 1909-1917 ◽  
Author(s):  
W. HOLLIK
Keyword(s):  
Top Quark ◽  
Z Boson ◽  
Vector Boson ◽  
Higgs Bosons ◽  
Precision Measurements ◽  
Negative Contribution ◽  
Mixing Angle ◽  
The Standard Model ◽  
Charged Higgs ◽  
Charged Higgs Bosons

The impacts of a heavy top quark on the relation between the vector boson masses and the mixing angle at the Z peak, the on-resonance asymmetries, and the Z decay widths are reviewed in the minimal model and extensions within SU (2) × U (1). Of particular interest are models with two scalar doublets where the charged Higgs bosons can give a sizeable negative contribution to the partial width [Formula: see text] This enhancement of the Standard Model top effect can be used to separate models with charged Higgs bosons coupling to the (t, b) doublet from other classes of models affecting only the ρ-parameter. Precision measurements of the Z partial widths will provide significant constraints on the two doublet models if the top quark is very heavy.

scholarly journals Higgs-Yukawa Model in Chirally Invariant Lattice Field Theory

2013 ◽  
Vol 2013 ◽  
pp. 1-24 ◽  
Author(s):  
John Bulava ◽  
Philipp Gerhold ◽  
Karl Jansen ◽  
Jim Kallarackal ◽  
Bastian Knippschild ◽  
...  
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
Boson Mass ◽  
Nonzero Temperature ◽  
Top Quark Mass ◽  
Yukawa Model ◽  
Lattice Field ◽  
The Standard Model ◽  
Yukawa Sector ◽  
Comprehensive Study

Nonperturbative numerical lattice studies of the Higgs-Yukawa sector of the standard model with exact chiral symmetry are reviewed. In particular, we discuss bounds on the Higgs boson mass at the standard model top quark mass and in the presence of heavy fermions. We present a comprehensive study of the phase structure of the theory at weak and very strong values of the Yukawa coupling as well as at nonzero temperature.

NEW BOUNDS ON THE HIGGS SECTOR OF MINIMAL SUSY

1990 ◽  
Vol 05 (16) ◽  
pp. 1259-1264 ◽  
Author(s):  
JORGE L. LOPEZ ◽  
D.V. NANOPOULOS
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Top Quark ◽  
Quark Mass ◽  
Higgs Mass ◽  
Higgs Sector ◽  
Boson Mass ◽  
Top Quark Mass ◽  
Supersymmetric Extension ◽  
The Standard Model

We examine the Higgs sector of the minimal supersymmetric extension of the standard model. The requirement of perturbative unification combined with the recent LEP data on Higgs boson searches, excludes substantial regions of parameter space. We find that only 0.42 ≤ tan β≲0.76 and tan β≳1.30 are the allowed values for tan β=υ2/υ1. We also determine the absolute lower bound on the lightest Higgs mass to be ≈8 GeV. We conclude that improved lower bounds on the top quark mass and/or the standard model Higgs boson mass will impose yet more stringent constraints on the model. These results clearly favor tan β>1, in agreement with N=1 supergravity or superstring-inspired models.

Sign in / Sign up

Export Citation Format

Share Document