scholarly journals THE LIMITS OF CUSTODIAL SYMMETRY

2010 ◽  
Vol 25 (27n28) ◽  
pp. 5082-5096
Author(s):  
R. SEKHAR CHIVUKULA ◽  
ROSHAN FOADI ◽  
ELIZABETH H. SIMMONS ◽  
STEFANO DI CHIARA
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
Quark Mass ◽  
Electroweak Symmetry ◽  
Top Quark Mass ◽  
Particle Content ◽  
Dirac Mass ◽  
The Standard Model ◽  
Custodial Symmetry ◽  
Weak Doublet

We introduce a toy model implementing the proposal of using a custodial symmetry to protect the [Formula: see text] coupling from large corrections. This "doublet-extended standard model" adds a weak doublet of fermions (including a heavy partner of the top quark) to the particle content of the standard model in order to implement an O(4) × U(1)X ~ SU(2)L × SU(2)R × PLR × U(1)X symmetry in the top-quark mass generating sector. This symmetry is softly broken to the gauged SU(2)L × U(1)Y electroweak symmetry by a Dirac mass M for the new doublet; adjusting the value of M allows us to explore the range of possibilities between the O(4)-symmetric (M → 0) and standard-model-like (M → ∞) limits.

TOP QUARK MASS IN THE CONDENSATE MODEL AND THE POSSIBILITY OF COLORED BOSONS

1993 ◽  
Vol 08 (26) ◽  
pp. 2465-2470 ◽  
Author(s):  
ANIRBAN KUNDU ◽  
TRIPTESH DE ◽  
BINAYAK DUTTA-ROY
Keyword(s):  
Top Quark ◽  
Quark Mass ◽  
Quark Condensate ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Top Quark Mass ◽  
Group Approach ◽  
Composite Bosons ◽  
The Standard Model ◽  
Renormalization Group Approach

The dynamical electroweak symmetry breaking of the Standard Model triggered by a top quark condensate (induced by an effective strong interaction, associated with a highenergy scale, of the form [Formula: see text]) usually requires an embarrassingly large top quark mass. A suggestion that this problem could be avoided through the introduction of an additional interaction [Formula: see text] (where [Formula: see text] are SU(3)c generators á la Okubo) is analyzed using the renormalization group approach. The mass of the top quark and the concomitant emergence of colored composite bosons is discussed.

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.

THE STANDARD MODEL WITH THREE GENERATIONS: CLOSING IN ON THE TOP QUARK MASS

1989 ◽  
Vol 04 (04) ◽  
pp. 753-768 ◽  
Author(s):  
F. HALZEN ◽  
C. S. KIM ◽  
S. PAKVASA
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Top Quark ◽  
Quark Mass ◽  
New Physics ◽  
Experimental Information ◽  
Beyond The Standard Model ◽  
Top Quark Mass ◽  
Three Generations ◽  
The Standard Model

Within the standard model with three generations we fit the top quark mass mt by combining experimental information of [Formula: see text] and [Formula: see text] mixing, CP-violation in K decay and the ratio Γ(W)/Γ(Z) extracted from [Formula: see text] collider data. We conclude that [Formula: see text] where the "systematic error" associated with theoretical ambiguities in performing the calculations is likely to be significantly larger than the quoted 10 GeV error associated with input parameters and experimental data. The anticipated value essentially guarantees the discovery of the top quark by existing experiments. Failure to discover it should force us to reconsider generally accepted calculational procedures before it signals new physics beyond the standard model. We discuss this in some detail.

NARROW-RESONANCE IN e−e− SCATTERING DUE TO ADDITIONAL GAUGE BOSON

1996 ◽  
Vol 11 (09) ◽  
pp. 1621-1625 ◽  
Author(s):  
PAUL H. FRAMPTON
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
Quark Mass ◽  
Special Role ◽  
Top Quark Mass ◽  
Narrow Resonance ◽  
Gauge Bosons ◽  
The Third ◽  
High Energies ◽  
The Standard Model

It now appears phenomenologically that the third family may be essentially different from the first two. Particularly the high value of the top quark mass suggests a special role. In the standard model all three families are treated similarly [becoming exactly the same at asymptotically high energies] so I need to extend the model to accommodate the goal of a really different third family. In this article I describe one such viable extension, the 331 model which predicts bileptonic gauge bosons.

CP-ODD PHENOMENA DUE TO FINITE WIDTH EFFECTS OF THE TOP QUARK

1991 ◽  
Vol 06 (21) ◽  
pp. 1933-1942 ◽  
Author(s):  
MAREK NOWAKOWSKI ◽  
APOSTOLOS PILAFTSIS
Keyword(s):  
Standard Model ◽  
Top Quark ◽  
Quark Mass ◽  
Quark Propagator ◽  
Upper Bounds ◽  
Coupling Constants ◽  
Charged Current ◽  
Finite Width ◽  
Top Quark Mass ◽  
The Standard Model

Strong experimental indications exist that the top quark mass in the Standard Model (SM) exceeds the mass of the W gauge boson. Since this opens the decay mode t → Wb a suitable regularization of the top quark propagator in the s-channel is required in many tree reactions. As in the Z0 case this regularization essentially results in an. additional imaginary contribution (iΓtmt) to the propagator. This absorptive phase can combine with complex coupling constants of the charged current sector to give rise to new CP violating effects. Theoretical upper bounds for the size of these CP-odd signals are estimated in various extensions of the SM such as: the four generation SM, left-right symmetric models and models with two or three Higgs doublets.

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.

scholarly journals HIGGS PARTICLES AT FUTURE HADRON AND ELECTRON-POSITRON COLLIDERS

1995 ◽  
Vol 10 (01) ◽  
pp. 1-63 ◽  
Author(s):  
A. DJOUADI
Keyword(s):  
Top Quark ◽  
Quark Mass ◽  
High Energy ◽  
High Energy Electron ◽  
Hadron Colliders ◽  
Top Quark Mass ◽  
Supersymmetric Extension ◽  
Fundamental Properties ◽  
Electron Positron ◽  
The Standard Model

The prospects for discovering Higgs particles and studying their fundamental properties at future high-energy electron-positron and hadron colliders are reviewed. Both the Standard Model Higgs boson and the Higgs particles of its minimal supersymmetric extension are discussed. We update various results by taking into account the new value of the top-quark mass obtained by the CDF Collaboration, and by including radiative corrections, some of which have been calculated only recently.

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).

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.

$B_d^0 \mbox{-} \bar{B}_d^0$ MIXING AND TOP QUARK MASS IN A FIELD THEORETIC QUARK MODEL

1993 ◽  
Vol 08 (20) ◽  
pp. 1869-1876 ◽  
Author(s):  
L. MAHARANA ◽  
A. NATH ◽  
A.R. PANDA
Keyword(s):  
Standard Model ◽  
Harmonic Oscillator ◽  
Quark Model ◽  
Top Quark ◽  
Charge Radius ◽  
Quark Mass ◽  
Free Parameter ◽  
Top Quark Mass ◽  
Mixing Parameter

[Formula: see text] mixing is considered in the framework of standard model. Using the [Formula: see text] mixing parameter xd, the mass of the top quark is predicted in a field theoretic quark model. The prediction depends on the only free parameter of the model, i.e., the harmonic oscillator radius. However, once the charge radius of the [Formula: see text]-meson is measured, one can have a definite prediction for top quark mass.

Sign in / Sign up

Export Citation Format

Share Document