scholarly journals Integrating out heavy fields in the path integral using the background-field method: general formalism

2021 ◽  
Vol 81 (9) ◽  
Author(s):  
Stefan Dittmaier ◽  
Sebastian Schuhmacher ◽  
Maximilian Stahlhofen
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Path Integral ◽  
General Procedure ◽  
Heavy Particle ◽  
Background Field ◽  
Tree Level ◽  
The Standard Model ◽  
The One ◽  
Heavy Higgs Boson

AbstractBuilding on an older method used to derive non-decoupling effects of a heavy Higgs boson in the Standard Model, we describe a general procedure to integrate out heavy fields in the path integral. The derivation of the corresponding effective Lagrangian including the one-loop contributions of the heavy particle(s) is particularly transparent, flexible, and algorithmic. The background-field formalism allows for a clear separation of tree-level and one-loop effects involving the heavy fields. Using expansion by regions the one-loop effects are further split into contributions from large and small momentum modes. The former are contained in Wilson coefficients of effective operators, the latter are reproduced by one-loop diagrams involving effective tree-level couplings. The method is illustrated by calculating potential non-decoupling effects of a heavy Higgs boson in a singlet Higgs extension of the Standard Model. In particular, we work in a field basis corresponding to mass eigenstates and properly take into account non-vanishing mixing between the two Higgs fields of the model. We also show that a proper choice of renormalization scheme for the non-standard sector of the underlying full theory is crucial for the construction of a consistent effective field theory.

The long journey to the Higgs boson and beyond at the LHC: Emphasis on CMS

2016 ◽  
Vol 31 (32) ◽  
pp. 1630058
Author(s):  
Tejinder Singh Virdee
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Hadron Collider ◽  
Heavy Particle ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Cms Experiment ◽  
The Standard Model ◽  
Electroweak Sector ◽  
The One

Since 2010 there has been a rich harvest of results on standard model physics by the ATLAS and CMS experiments operating on the Large Hadron Collider. In the summer of 2012, a spectacular discovery was made by these experiments of a new, heavy particle. All the subsequently analysed data point strongly to the properties of this particle as those expected for the Higgs boson associated with the Brout–Englert–Higgs mechanism postulated to explain the spontaneous symmetry breaking in the electroweak sector, thereby explaining how elementary particles acquire mass. This article focuses on the CMS experiment, the technological challenges encountered in its construction, describing some of the physics results obtained so far, including the discovery of the Higgs boson, and searches for the widely anticipated new physics beyond the standard model, and peer into the future involving the high-luminosity phase of the LHC. This article is complementary to the one by Peter Jenni4 that focuses on the ATLAS experiment.

ONE LOOP-INDUCED WZH COUPLING IN THE TWO HIGGS DOUBLET MODEL

1989 ◽  
Vol 04 (28) ◽  
pp. 2757-2766 ◽  
Author(s):  
THOMAS G. RIZZO
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
New Physics ◽  
Tree Level ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Charged Higgs ◽  
Doublet Model ◽  
The One ◽  
Two Higgs Doublet Model

Although absent at the tree level in models with only doublet and singlet Higgs representations, the WZH coupling can be induced at the one-loop level. We examine the size of this induced coupling in the two Higgs doublet model due to fermion as well as Higgs/gauge boson loops. Such couplings could provide a new mechanism for charged Higgs production at colliders and are ‘backgrounds’ to new physics beyond the Standard Model. We find, however, that these couplings are very weak for all regions of the parameter space explored.

scholarly journals Quark-flavor-changing Higgs decays from a universal extra dimension

2020 ◽  
Vol 35 (24) ◽  
pp. 2050141
Author(s):  
Carlos M. Farrera ◽  
Alejandro Granados-González ◽  
Héctor Novales-Sánchez ◽  
J. Jesús Toscano
Keyword(s):  
Standard Model ◽  
Extra Dimension ◽  
New Physics ◽  
Tree Level ◽  
Universal Extra Dimension ◽  
Loop Level ◽  
Flavor Changing ◽  
The Standard Model ◽  
The One ◽  
Kaluza Klein

Kaluza–Klein fields characterizing, from a four-dimensional viewpoint, the presence of compact universal extra dimensions would alter low-energy observables through effects determined by some compactification scale, [Formula: see text], since the one-loop level, thus being particularly relevant for physical phenomena forbidden at tree level by the Standard Model. This paper explores, for the case of one universal extra dimension, such new-physics contributions to Higgs decays [Formula: see text], into pairs of quarks with different flavors, a sort of decay process which, in the Standard Model, strictly occurs at the loop level. Finite results, decoupling as [Formula: see text], are calculated. Approximate short expressions, valid for large compactification scales, are provided. We estimate that Kaluza–Klein contributions lie below predictions from the Standard Model, being about 2 to 3 orders of magnitude smaller for compactification scales within [Formula: see text].

AN SU(2)L×U(1)L×U(1)R MODEL WITH FINITE DIRAC NEUTRINO MASSES

1993 ◽  
Vol 08 (10) ◽  
pp. 895-902 ◽  
Author(s):  
SUBHASH RAJPOOT
Keyword(s):  
Standard Model ◽  
Discrete Symmetry ◽  
Lepton Number ◽  
Tree Level ◽  
Neutrino Masses ◽  
Charged Scalar ◽  
Dirac Neutrino ◽  
Left Handed ◽  
The Standard Model ◽  
The One

An SU(2)L×U(1)L×U(1)R model of electroweak interactions is presented in which the conventional fermions of the standard model are left-handed doublets under SU(2)L× U(1)L and are right-handed singlets under U(1) R . The triangle anomalies are canceled by adding vector-like singlet fermions. Neutrinos are massless at the tree level due to a discrete symmetry and acquire tiny finite masses at the one-loop level due to the exchange of two charged scalar singlets. The singlet scalars carry two units of lepton number.

scholarly journals 126 GeV HIGGS BOSON PAIR PRODUCTION AT THE LINEAR COLLIDER IN THE NONCOMMUTATIVE SPACE–TIME

2013 ◽  
Vol 28 (01) ◽  
pp. 1350004 ◽  
Author(s):  
PRASANTA KUMAR DAS ◽  
ABHISHODH PRAKASH
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Pair Production ◽  
Cross Section ◽  
Linear Collider ◽  
Noncommutative Space ◽  
Tree Level ◽  
Boson Pair ◽  
Boson Pair Production ◽  
The Standard Model

We study the 126 GeV Higgs boson pair production through e+e- collision in the noncommutative extension of the standard model using the Seiberg–Witten map of this to the first order of the noncommutative parameter Θμν. The process is forbidden in the standard model at the tree level. We study the time-averaged cross-section of the pair production at TeV scale linear collider and investigate the sensitivity of the cross-section on the orientation angle η and the noncommutative scale Λ. We found that Λ lies in the range 0.5 TeV–1.0 TeV, which can be reached by the upcoming linear collider.

THE STRENGTH OF TRILINEAR HIGGS BOSON COUPLING IN COMPOSITE MODELS

2007 ◽  
Vol 16 (09) ◽  
pp. 2979-2983 ◽  
Author(s):  
A. DOFF ◽  
A. A. NATALE
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Standard Model Higgs Boson ◽  
Self Energy ◽  
The Standard Model ◽  
Composite Models ◽  
Model Independent ◽  
Boson Coupling ◽  
The One

In this work we discuss the strength of the trilinear Higgs boson coupling in composite models in a model independent way. The coupling is determined as a function of a very general ansatz for the fermionic self-energy, and turns out to be equal or smaller than the one of the Standard Model Higgs boson depending on the dynamics of the theory.

Heavy-Higgs-boson decays toW+W−Zin the standard model

1992 ◽  
Vol 46 (11) ◽  
pp. 5069-5073 ◽  
Author(s):  
Paul Langacker ◽  
Jiang Liu
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
The Standard Model ◽  
Heavy Higgs Boson

The QCD corrections of the process h → ηbZ

2018 ◽  
Vol 33 (15) ◽  
pp. 1830008
Author(s):  
Rong-Fei Zhu ◽  
Tai-Fu Feng ◽  
Hai-Bin Zhang
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Quantum Chromodynamics ◽  
Branching Ratio ◽  
Tree Level ◽  
Relative Correction ◽  
Loop Level ◽  
The Standard Model ◽  
Key Parameter

We investigate the 125 GeV Higgs boson decay to a pseudoscalar quarkonium [Formula: see text] and [Formula: see text] boson. We calculate the quantum chromodynamics (QCD) one-loop corrections to the branching ratio of the process, [Formula: see text], both in the Standard Model (SM) and in the two Higgs double models (THDM). Adding the QCD one-loop corrections, the branching ratio of [Formula: see text] in the SM is [Formula: see text]. The relative correction of that QCD one-loop level relative to the tree level of [Formula: see text] is around 76% in the SM. Similarly, the relative correction in the THDM also can be around 75%. The key parameter, [Formula: see text], can affect the relative correction in the THDM.

scholarly journals DIMINISHED UPPER BOUNDS ON THE UNIFICATION MASS SCALES FOR HEAVY HIGGS BOSON MASSES

2006 ◽  
Vol 21 (03) ◽  
pp. 209-212
Author(s):  
V. ELIAS ◽  
S. HOMAYOUNI ◽  
D. J. JEFFREY
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Higgs Sector ◽  
Upper Bounds ◽  
Higher Order ◽  
Scalar Coupling ◽  
Scalar Couplings ◽  
The Standard Model ◽  
Β Function ◽  
Heavy Higgs Boson

We consider dominant three-, four- and five-loop contributions to λ, the quartic scalar coupling-constant's β-function in the Standard Model. We find that these terms accelerate the evolution of λ to nonperturbative values, thereby lowering the unification bound for which scalar-couplings are still perturbative. We also find that these higher order contributions imply a substantial lowering of λ itself before the anticipated onset of nonperturbative physics in the Higgs sector.

scholarly journals Decays Z → γγ and Z → gg in the Standard Model Extension

2015 ◽  
Vol 30 (35) ◽  
pp. 1550216 ◽  
Author(s):  
J. Castro-Medina ◽  
H. Novales-Sanchez ◽  
J. J. Toscano ◽  
E. S. Tututi
Keyword(s):  
Standard Model ◽  
Background Field ◽  
Standard Model Extension ◽  
Gauge Invariant ◽  
Spatial Component ◽  
Loop Level ◽  
Model Extension ◽  
The Standard Model ◽  
Decay Widths ◽  
The One

The [Formula: see text] and [Formula: see text] decays are studied in the context of the renormalizable version of the Standard Model Extension. The [Formula: see text]-odd [Formula: see text] bilinear interaction, which involves the constant background field [Formula: see text] and which has been a subject of interest in literature, is considered. It is shown that the [Formula: see text] and [Formula: see text] decays, which are strictly zero in the standard model, can be generated radiatively at the one-loop level. It is found that these decays are gauge invariant and free of ultraviolet divergences, and that the corresponding decay widths only depend on the spatial component of the background field [Formula: see text].

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