scholarly journals An Analysis of a Minimal Vectorlike Extension of the Standard Model

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
V. Beylin ◽  
M. Bezuglov ◽  
V. Kuksa ◽  
N. Volchanskiy
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Symmetry Breaking ◽  
Global Symmetry ◽  
Fundamental Field ◽  
Goldstone Bosons ◽  
The Standard Model ◽  
Vector Bosons ◽  
The Stability ◽  
Intermediate Vector

We analyze an extension of the Standard Model with an additionalSU(2)hypercolor gauge group keeping the Higgs boson as a fundamental field. Vectorlike interactions of new hyperquarks with the intermediate vector bosons are explicitly constructed. We also consider pseudo-Nambu–Goldstone bosons caused by the symmetry breakingSU(4)→Sp(4). A specific global symmetry of the model with zero hypercharge of the hyperquark doublets ensures the stability of a neutral pseudoscalar field. Some possible manifestations of the lightest states at colliders are also examined.

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 BOSONIC SEESAW AND A SOLUTION TO THE μ PROBLEM IN THE UNPARTICLE PHYSICS

2010 ◽  
Vol 25 (09) ◽  
pp. 691-701
Author(s):  
TATSURU KIKUCHI
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Symmetry Breaking ◽  
Conformal Symmetry ◽  
New Physics ◽  
Electroweak Symmetry Breaking ◽  
Effective Theory ◽  
Electroweak Symmetry ◽  
Hidden Sector ◽  
The Standard Model

Recently, conceptually new physics beyond the Standard Model has been proposed by Georgi, where a new physics sector becomes conformal and provides "unparticle" which couples to the Standard Model sector through higher dimensional operators in low energy effective theory. Among several possibilities, we focus on operators involving the unparticle and Higgs boson. Once the Higgs develops the vacuum expectation value (VEV), the conformal symmetry is broken and as a result, the mixing between the unparticle and the Higgs boson emerges. In the former part of this paper, we consider a natural realization of bosonic seesaw in the context of unparticle physics. In this framework, the negative mass squared or the electroweak symmetry breaking vacuum is achieved as a result of mass matrix diagonalization. So, the bosonic seesaw mechanism for the electroweak symmetry breaking can naturally be understood in the framework of unparticle physics. In the latter part of this paper, we consider the unparticle as a hidden sector of supersymmetry breaking, and give some phenomenological consequences of this scenario. The result shows that there is a possibility for the unparticle as a hidden sector in SUSY breaking sector, and can provide a solution to the μ problem in SUSY models.

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.

The Higgs Boson

2019 ◽  
pp. 327-342
Author(s):  
Michael E. Peskin
Keyword(s):  
Higgs Boson ◽  
Large Hadron Collider ◽  
Standard Model ◽  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Hadron Collider ◽  
Higgs Bosons ◽  
The Standard Model

This chapter discusses the Higgs boson, the spin-0 particle in the Standard Model most closely associated with its spontaneous symmetry breaking. It gives the predictions of the Standard Model for the production and decay of Higgs bosons. It describes the experiments at the Large Hadron Collider that test these predictions.

scholarly journals Models of hypercolor based on symplectic gauge group with three heavy vectorlike hyperquarks

2019 ◽  
Vol 28 (13) ◽  
pp. 1941002 ◽  
Author(s):  
Nikolay Volchanskiy ◽  
Vladimir Kuksa ◽  
Vitaly Beylin
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Symmetry Group ◽  
Gauge Group ◽  
Global Symmetry ◽  
Composite Higgs ◽  
Global Symmetry Group ◽  
The Standard Model ◽  
Dynamical Breaking ◽  
Partially Composite

We study possibilities to extend the Standard Model (SM) by three flavors of vectorlike heavy quarks in pseudoreal representation of symplectic hypercolor gauge group. This extension of SM predicts a rich spectra of heavy composite hypermesons and hyperbaryons (all of them carry integer spins) including 14 pseudo-Nambu–Goldstone states emerging in dynamical breaking of the global symmetry group of the H-quarks, [Formula: see text], to its Sp(6) subgroup. The properties of the lightest states depend strongly on the choice of heavy-quark hypercharges. Our focus is placed on the variants of the model with partially composite Higgs boson, i.e. the experimentally observed boson comprised the elementary SM Higgs and a mixture of H-hadrons.

scholarly journals The Standard Model of Electroweak Interactions

2020 ◽  
pp. 35-81
Author(s):  
Guido Altarelli ◽  
Stefano Forte
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Matter Content ◽  
Higgs Particle ◽  
Electroweak Interactions ◽  
The Standard Model ◽  
Vector Bosons ◽  
Intermediate Vector

AbstractIn this chapter, we summarize the structure of the standard EW theory and specify the couplings of the intermediate vector bosons W±, Z and of the Higgs particle with the fermions and among themselves, as dictated by the gauge symmetry plus the observed matter content and the requirement of renormalizability

The Standard Model and Experiment

2021 ◽  
pp. 442-478
Author(s):  
J. Iliopoulos ◽  
T.N. Tomaras
Keyword(s):  
Standard Model ◽  
Heavy Quark ◽  
The Other ◽  
Hadron Spectroscopy ◽  
The Standard Model ◽  
Vector Bosons ◽  
The Rich ◽  
Basic Experiments ◽  
Intermediate Vector ◽  
Theory And Experiment

We review some basic experiments which established the validity of the Standard Model. They include the discovery of charm as well as the other two heavy quark flavours, that of the intermediate vector bosons W± and Z and of the BEH scalar. We show the successes of the model in the domain of hadron spectroscopy, but also its shortcomings. The rich subject of CP-violation in the hadronic and the leptonic sectors is reviewed, as well as the questions of flavour violating transitions. We end with an overall comparison between theory and experiment and point out the few cases in which some tension persists.

scholarly journals VACUUM STABILITY IN THE STANDARD MODEL

2013 ◽  
Vol 28 (04) ◽  
pp. 1330002 ◽  
Author(s):  
YONG TANG
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Planck Scale ◽  
New Physics ◽  
Standard Model Higgs Boson ◽  
Higgs Particle ◽  
Vacuum Stability ◽  
The Standard Model ◽  
The Stability ◽  
Theoretical Issues

The long-awaited Higgs particle H around 125 GeV has been observed at the LHC. Interpreting it as the Standard Model Higgs boson and if there is no new physics between electroweak and Planck scale, we then do not have a stable vacuum. Here, we give a brief review of the electroweak vacuum stability and some related theoretical issues in the Standard Model. Possible ways to save the stability are also discussed.

scholarly journals Search for π0 decays to invisible particles

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
E. Cortina Gil ◽  
◽  
A. Kleimenova ◽  
E. Minucci ◽  
S. Padolski ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Branching Ratio ◽  
Standard Model Higgs Boson ◽  
Scalar Mixing ◽  
Upper Limit ◽  
Upper Limits ◽  
The Standard Model ◽  
Model Independent

Abstract The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 109 tagged π0 mesons from K+ → π+π0(γ), searching for the decay of the π0 to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4.4 × 10−9 is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay K+ → π+X, where X is a particle escaping detection with mass in the range 0.110–0.155 GeV/c2 and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming X to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.

scholarly journals Search for dark photons in Higgs boson production via vector boson fusion in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
T. Bergauer ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Branching Fraction ◽  
Vector Boson ◽  
Boson Mass ◽  
Higgs Boson Mass ◽  
Vector Boson Fusion ◽  
Upper Limit ◽  
The Standard Model

Abstract A search is presented for a Higgs boson that is produced via vector boson fusion and that decays to an undetected particle and an isolated photon. The search is performed by the CMS collaboration at the LHC, using a data set corresponding to an integrated luminosity of 130 fb−1, recorded at a center-of-mass energy of 13 TeV in 2016–2018. No significant excess of events above the expectation from the standard model background is found. The results are interpreted in the context of a theoretical model in which the undetected particle is a massless dark photon. An upper limit is set on the product of the cross section for production via vector boson fusion and the branching fraction for such a Higgs boson decay, as a function of the Higgs boson mass. For a Higgs boson mass of 125 GeV, assuming the standard model production rates, the observed (expected) 95% confidence level upper limit on the branching fraction is 3.5 (2.8)%. This is the first search for such decays in the vector boson fusion channel. Combination with a previous search for Higgs bosons produced in association with a Z boson results in an observed (expected) upper limit on the branching fraction of 2.9 (2.1)% at 95% confidence level.

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