scholarly journals DEVIATIONS FROM LOW-ENERGY THEOREM FOR VLVL SCATTERING DUE TO PSEUDO-GOLDSTONE BOSONS

1998 ◽  
Vol 13 (38) ◽  
pp. 3045-3061
Author(s):  
TOMÁS BAHNÍK ◽  
JIŘÍ HOŘEJSÍ
Keyword(s):  
Symmetry Breaking ◽  
Symmetric Space ◽  
Vector Boson ◽  
Goldstone Boson ◽  
Electroweak Symmetry Breaking ◽  
Low Energy ◽  
Tree Level ◽  
Electroweak Symmetry ◽  
Goldstone Bosons ◽  
Vector Bosons

Possible deviations from a low-energy theorem for the scattering of strongly interacting longitudinally polarized W and Z bosons are discussed within a particular scheme of electroweak symmetry breaking. The scheme (suggested earlier by other authors in a slightly different context) is based on spontaneous breakdown of an SU(4) symmetry to custodial SU(2) subgroup. The physical spectrum of such a model contains a set of relatively light pseudo-Goldstone bosons whose interactions with vector bosons modify the low-energy theorem proven for a "minimal" symmetry-breaking sector The Goldstone-boson manifold SU(4)/SU(2) is not a symmetric space. In this context it is observed that, on the other hand, there is a large class of models of electroweak symmetry breaking, involving groups G and H such that the G/H is a symmetric space and the corresponding rich multiplets of pseudo-Goldstone bosons do not influence the canonical low-energy theorem. For the scheme considered here, the relevant interactions are described in terms of an effective chiral Lagrangian and tree-level contributions of the pseudo-Goldstone boson exchanges to the vector boson scattering are computed explicitly. A comparison with the standard model is made.

scholarly journals Connecting Electroweak Symmetry Breaking and Flavor: A Light Dilaton D and a Sequential Heavy Quark Doublet Q

Symmetry ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 312
Author(s):  
Wei-Shu Hou
Keyword(s):  
Symmetry Breaking ◽  
Yukawa Coupling ◽  
Vector Boson ◽  
Hadron Collider ◽  
Goldstone Boson ◽  
Gluon Fusion ◽  
New Physics ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Mass Generation

The 125 GeV boson is quite consistent with the Higgs boson of the Standard Model (SM), but there is a challenge from Anderson as to whether this particle is in the Lagrangian. As Large Hadron Collider (LHC) Run 2 enters its final year of running, we ought to reflect and make sure we have gotten everything right. The ATLAS and CMS combined Run 1 analysis claimed a measurement of 5.4σ vector boson fusion (VBF) production which is consistent with SM, which seemingly refutes Anderson. However, to verify the source of electroweak symmetry breaking (EWSB), we caution that VBF measurement is too important for us to be imprudent in any way, and gluon–gluon fusion (ggF) with similar tag jets must be simultaneous measured, which should be achievable in LHC Run 2. The point is to truly test the dilaton possibility—the pseudo-Goldstone boson of scale invariance violation. We illustrate EWSB by dynamical mass generation of a sequential quark doublet (Q) via its ultrastrong Yukawa coupling and argue how this might be consistent with a 125 GeV dilaton, D. The ultraheavy 2mQ≳4–5 TeV scale explains the absence of New Physics so far, while the mass generation mechanism shields us from the UV theory for the strong Yukawa coupling. Collider and flavor physics implications are briefly touched upon. Current Run 2 analyses show correlations between the ggF and VBF measurements, but the newly observed tt¯H production at LHC poses a challenge.

scholarly journals A GENERAL HIGGS SECTOR: CONSTRAINTS AND PHENOMENOLOGY

1996 ◽  
Vol 11 (29) ◽  
pp. 5221-5243 ◽  
Author(s):  
ANIRBAN KUNDU ◽  
BISWARUP MUKHOPADHYAYA
Keyword(s):  
Symmetry Breaking ◽  
Precision Measurement ◽  
General Structure ◽  
Higgs Sector ◽  
Electroweak Symmetry Breaking ◽  
Higgs Bosons ◽  
Tree Level ◽  
Electroweak Symmetry ◽  
Interaction Terms ◽  
Scalar Sector

We have investigated some phenomenological aspects of an SU (2) × U (1) scenario where scalars belonging to arbitrary representations of SU(2) are involved in electroweak symmetry breaking. The resulting interaction terms are derived. Some constraints are obtained on the arbitrary scalar sector from the requirement of tree-level unitarity in longitudinal gauge boson scattering. We also show that there is a remarkable complimentarity between the constraints on a general structure from the ρ parameter and those from precision measurement of the [Formula: see text] vertex. Finally, some salient features about the production of such Higgs bosons in e+e− collision are discussed.

scholarly journals Bootstrap Dynamical Symmetry Breaking

2013 ◽  
Vol 2013 ◽  
pp. 1-19
Author(s):  
Wei-Shu Hou
Keyword(s):  
Symmetry Breaking ◽  
Yukawa Coupling ◽  
Dynamical Symmetry ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Light Higgs Boson ◽  
Gap Equation ◽  
Dynamical Symmetry Breaking ◽  
Longitudinal Modes ◽  
Goldstone Bosons

Despite the emergence of a 125 GeV Higgs-like particle at the LHC, we explore the possibility of dynamical electroweak symmetry breaking by strong Yukawa coupling of very heavy new chiral quarksQ. Taking the 125 GeV object to be a dilaton with suppressed couplings, we note that the Goldstone bosonsGexist as longitudinal modesVLof the weak bosons and would couple toQwith Yukawa couplingλQ. WithmQ≳700 GeV from LHC, the strongλQ≳4could lead to deeply boundQQ¯states. We postulate that the leading “collapsed state,” the color-singlet (heavy) isotriplet, pseudoscalarQQ¯mesonπ1, isGitself, and a gap equation without Higgs is constructed. Dynamical symmetry breaking is affected via strongλQ, generatingmQwhile self-consistently justifying treatingGas massless in the loop, hence, “bootstrap,” Solving such a gap equation, we find thatmQshould be several TeV, orλQ≳4π, and would become much heavier if there is a light Higgs boson. For such heavy chiral quarks, we find analogy with theπ−Nsystem, by which we conjecture the possible annihilation phenomena ofQQ¯→nVLwith high multiplicity, the search of which might be aided by Yukawa-boundQQ¯resonances.

scholarly journals Low-energy signals of strongly-coupled electroweak symmetry-breaking scenarios

2016 ◽  
Vol 93 (5) ◽  
Author(s):  
Antonio Pich ◽  
Ignasi Rosell ◽  
Joaquín Santos ◽  
Juan José Sanz-Cillero
Keyword(s):  
Symmetry Breaking ◽  
Electroweak Symmetry Breaking ◽  
Low Energy ◽  
Electroweak Symmetry ◽  
Strongly Coupled

Links between flavor and electroweak symmetry breaking

2014 ◽  
Vol 29 (21) ◽  
pp. 1444007
Author(s):  
George Wei-Shu Hou
Keyword(s):  
Symmetry Breaking ◽  
Scale Invariance ◽  
Vector Boson ◽  
New Physics ◽  
Electroweak Symmetry Breaking ◽  
Fermion Mass ◽  
Electroweak Symmetry ◽  
Mass Generation ◽  
Gap Equation ◽  
The Standard Model

Fermion mass generation in the standard model was invented by Weinberg, while it is an old notion that strong Yukawa coupling could be the agent of electroweak symmetry breaking. Observation of the 126 GeV boson has crashed the prospects for such a heavy chiral quark doublet Q. However, the dilaton possibility can only be ruled out by confirming vector boson fusion with Run 2 data at the LHC, which starts only in 2015. We recast the [Formula: see text] condensation scenario as Fermi–Yang model v2.0. A Gap Equation has been constructed, with numerical solution demonstrating dynamical mQ generation; scale invariance of this equation may be consistent with a dilaton. Other consequences to be checked are [Formula: see text] "annihilation stars," and enhanced Bd →μ+μ-, KL →π0νν, and possibly sin ϕs. If verified in Nature, the Agent of BEH mechanism would differ from current perception, the 126 GeV boson would be the first New Physics at the LHC, and we would have enough CP violation for baryogenesis.

CHARGE-1/2 FERMIONS AND THE SU(4) COLOR MODEL

1992 ◽  
Vol 07 (15) ◽  
pp. 1315-1323 ◽  
Author(s):  
ROBERT FOOT ◽  
OSCAR F. HERNÁNDEZ
Keyword(s):  
Symmetry Breaking ◽  
Mass Range ◽  
Electroweak Symmetry Breaking ◽  
Low Energy ◽  
Color Model ◽  
Electroweak Symmetry ◽  
The Standard Model ◽  
Energy Theory ◽  
Electrically Charged ◽  
Breaking Scale

The SU(4) color models represent possible alternatives to the standard model. These theories replace the color gauge group SU(3) c by SU(4) c . The SU(4) c symmetry is assumed to be broken which leads to the SM as the effective low energy theory. An interesting feature of these theories is that the SU(4) symmetry breaking scale can be very low, and may be approximately at the same scale as the electroweak symmetry breaking. These models imply the existence of exotic electrically charged ±1/2 fermions. We examine various SU(4) c models to explore the circumstances under which these models can have the exotic charged fermions in the interesting mass range m≳100 GeV .

scholarly journals Is SMEFT enough?

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Timothy Cohen ◽  
Nathaniel Craig ◽  
Xiaochuan Lu ◽  
Dave Sutherland
Keyword(s):  
Standard Model ◽  
Symmetry Breaking ◽  
Independent Set ◽  
Higgs Doublet ◽  
New Physics ◽  
Effective Field ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Goldstone Bosons ◽  
The Standard Model

Abstract There are two canonical approaches to treating the Standard Model as an Effective Field Theory (EFT): Standard Model EFT (SMEFT), expressed in the electroweak symmetric phase utilizing the Higgs doublet, and Higgs EFT (HEFT), expressed in the broken phase utilizing the physical Higgs boson and an independent set of Goldstone bosons. HEFT encompasses SMEFT, so understanding whether SMEFT is sufficient motivates identifying UV theories that require HEFT as their low energy limit. This distinction is complicated by field redefinitions that obscure the naive differences between the two EFTs. By reformulating the question in a geometric language, we derive concrete criteria that can be used to distinguish SMEFT from HEFT independent of the chosen field basis. We highlight two cases where perturbative new physics must be matched onto HEFT: (i) the new particles derive all of their mass from electroweak symmetry breaking, and (ii) there are additional sources of electroweak symmetry breaking. Additionally, HEFT has a broader practical application: it can provide a more convergent parametrization when new physics lies near the weak scale. The ubiquity of models requiring HEFT suggests that SMEFT is not enough.

scholarly journals INVESTIGATIONS OF ELECTROWEAK SYMMETRY BREAKING MECHANISM FOR HIGGS BOSON DECAYS INTO FOUR FERMIONS

2020 ◽  
pp. 8-12
Author(s):  
T.V. Obikhod ◽  
E.A. Petrenko
Keyword(s):  
Higgs Boson ◽  
Symmetry Breaking ◽  
Gluon Fusion ◽  
Higgs Doublet ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Decay Modes ◽  
Significant Difference ◽  
Vector Bosons ◽  
Breaking Mechanism

Models with extended Higgs boson sectors are of prime importance for investigating the mechanism of electroweak symmetry breaking for Higgs decays into four fermions and for Higgs-production in association with a vector bosons. In the framework of the Two-Higgs-Doublet Model using two scenarios obtained from the experimental measurements we presented next-to-leading-order results on the four-fermion decays of light CP-even Higgs boson, h → 4f. With the help of Monte Carlo program Prophecy 4f 3.0, we calculated the values Γ = ΓEW/(ΓEW + ΓSM) and Γ = ΓEW+QCD/(ΓEW+QCD + ΓSM) for Higgs boson decay channels H → νµµeνe, µµee, eeee. We didn’t find significant difference when accounting QCD corrections to EW processes in the decay modes of Higgs boson. Using computer programs Pythia 8.2 and FeynHiggs we calculated the following values: σ(V BH)BR(H → ZZ) and σ(V BF)BR(H → WW) for VBF production processes, σ(ggH)BR(H → WW) and σ(ggH)BR(H → ZZ) for gluon fusion production process at 13 and 14 TeV and found good agreement with experimental data.

HIGGS DOUBLET AS COMPOSITE GOLDSTONE BOSON: CHALLENGE TO MULTI-TEV ENERGY COLLIDERS

1992 ◽  
Vol 07 (26) ◽  
pp. 6473-6492 ◽  
Author(s):  
YU. F. PIROGOV
Keyword(s):  
Standard Model ◽  
Symmetry Breaking ◽  
Goldstone Boson ◽  
Higgs Doublet ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Nonlinear Realization ◽  
Collider Phenomenology ◽  
Effective Lagrangian ◽  
The Standard Model

The minimum nonlinear extension SU(3)×U(1)/SU(2)×U(1) to the Standard Model, where the Higgs doublet is a composite Goldstone boson, is investigated. The canonical nonlinear realization of the extended symmetry is constructed in the form maximally close to that of the Standard Model. The corresponding most general effective Lagrangian is built. A simplest linear realization of the extended symmetry in an extended fermion sector is found. The Higgs-Goldstone scenario of the electroweak symmetry breaking is outlined from the standpoint of the multi-TeV energy collider phenomenology.

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