scholarly journals The simplest 3-3-1 model

2016 ◽  
Vol 31 (10) ◽  
pp. 1650062 ◽  
Author(s):  
Le Tho Hue ◽  
Le Duc Ninh
Keyword(s):  
Standard Model ◽  
Gauge Group ◽  
Electric Charge ◽  
Energy Scale ◽  
Tree Level ◽  
Simple Extension ◽  
Flavor Changing ◽  
The Standard Model ◽  
Custodial Symmetry ◽  
Free Parameters

A simple extension of the Standard Model (SM), based on the gauge group [Formula: see text] with [Formula: see text] being the hypercharge, is considered. We show that, by imposing an approximate global [Formula: see text] custodial symmetry at the SM energy scale, the [Formula: see text] mixing is absent at tree level and the value of the [Formula: see text] parameter can be kept close to one. Tree-level flavor-changing neutral currents (FCNCs) are also reduced to three particles, namely [Formula: see text], a CP-odd Higgs and a CP-even Higgs. The model predicts new leptons with electric charges of ±1/2e and new quarks with ±1/6e charges as well as new gauge and scalar bosons with ±1/2e charges. Electric charge conservation requires that one of them must be stable. Their masses are unfortunately free parameters.

scholarly journals Zeros of amplitude in the associated production of photon and leptoquark at $$\varvec{e}$$-$$\varvec{p}$$ collider

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Priyotosh Bandyopadhyay ◽  
Saunak Dutta ◽  
Anirban Karan
Keyword(s):  
Standard Model ◽  
Gauge Group ◽  
Single Photon ◽  
Tree Level ◽  
Associated Production ◽  
The Standard Model ◽  
Radiation Amplitude ◽  
Complementary Set

AbstractThough various extensions of the Standard Model with higher gauge group predict the existence of leptoquarks, none of them has been observed yet at any of the colliders. In this paper, we study the prospect of several past and future $$e$$ e -$$p$$ p colliders like HERA, LHeC and FCC-he to detect them through radiation amplitude zero. We find that the leptoquarks showing zeros in the tree-level single-photon amplitudes at $$e$$ e -$$p$$ p collider lie within the complementary set of those exhibiting zeros at e-$$\gamma $$ γ collider. We present a PYTHIA-based analysis for HERA, LHeC and FCC-he (run II) to detect the leptoquarks with masses 70 GeV, 900 GeV and 1.5 TeV (2.0 TeV) respectively through radiation amplitude zero.

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].

scholarly journals LEPTONIC CUSTODIAL SYMMETRY, QUANTIZATION OF THE ELECTRIC CHARGE AND THE NEUTRINO IN THE STANDARD MODEL

1996 ◽  
Vol 11 (28) ◽  
pp. 2297-2307
Author(s):  
B. MACHET
Keyword(s):  
Standard Model ◽  
Electric Charge ◽  
Majorana Neutrino ◽  
Hidden Sector ◽  
Majorana Particle ◽  
Leptonic Sector ◽  
The Standard Model ◽  
Custodial Symmetry ◽  
Vectorial Model

I study, in the leptonic sector, the role of the SU (2)v custodial symmetry [Formula: see text] which was shown in Ref. 1 to control the quantization of the electric charge in the J=0 mesonic sector. The electroweak theory is considered, according to Ref. 2, as a purely vectorial model which interacts with a “hidden” sector of composite scalars. [Formula: see text] can only be a symmetry of the former if the neutrino is a Majorana particle; the latter provides a dynamical modification of the leptonic weak couplings, reconstructing those of the standard model with a massless Majorana neutrino.

scholarly journals (g − 2)μ versus K → π + Emiss induced by the (B − L)23 boson

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Zhaofeng Kang ◽  
Yoshihiro Shigekami
Keyword(s):  
Cp Violation ◽  
Standard Model ◽  
Neutral Current ◽  
Tree Level ◽  
Meson Decays ◽  
Loop Level ◽  
Flavor Changing ◽  
The Standard Model ◽  
Flavor Changing Neutral Current

Abstract To address the long-standing (g − 2)μ anomaly via a light boson, in ref. [1] we proposed to extend the standard model (SM) by the local (B − L)23, under which only the second and third generations of fermions are charged. It predicts an invisible Z′ with mass $$ \mathcal{O}(100) $$ O 100 MeV, and moreover it has flavor-changing neutral current (FCNC) couplings to the up-type quarks at tree level. Such a Z′, via KL→ π0 + Z′(→$$ v\overline{v} $$ v v ¯ ) at loop level, may be a natural candidate to account for the recent KOTO anomaly. In this article, we investigate this possibility, to find that Z′ can readily do this job if it is no longer responsible for the (g − 2)μ anomaly. We further find that both anomalies can be explained with moderate tuning of the CP violation, but may contradict the B meson decays.

ELECTRIC CHARGE QUANTIZATION AND VECTOR-LIKE FERMIONS

1990 ◽  
Vol 05 (24) ◽  
pp. 1947-1949 ◽  
Author(s):  
ROBERT FOOT
Keyword(s):  
Standard Model ◽  
Electric Charge ◽  
Life Time ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Simple Method ◽  
Gauge Models ◽  
Flavor Changing ◽  
Charge Quantization ◽  
The Standard Model

In extended gauge models with gauge group G, electric charge quantization is not always an automatic consequence of the consistency of the theory. Exotic fermions which have SU (3) ⊗ SU (2) L ⊗ U (1) invariant mass terms can provide a simple method for preserving the charge quantization feature of the standard model. This procedure is applied to the segregated isospin model.This approach indicates that precision measurements of the τ-lepton life-time and rare flavor-changing neutral processes may provide the first indications of new physics beyond the standard model.

scholarly journals ALTERNATIVE IMPLEMENTATION OF THE HIGGS BOSON

2011 ◽  
Vol 26 (07) ◽  
pp. 461-467
Author(s):  
ROBERT FOOT ◽  
ARCHIL KOBAKHIDZE
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Gauge Invariance ◽  
Degrees Of Freedom ◽  
Energy Scale ◽  
Tree Level ◽  
Radiative Corrections ◽  
Gauge Bosons ◽  
The Standard Model ◽  
Low Energies

We discuss an alternative implementation of the Higgs boson within the Standard Model which is possible if the renormalizability condition is relaxed. Namely, at energy scale Λ the Higgs boson interacts at tree-level only with matter fermions, while the full gauge invariance is still maintained. The interactions with the electroweak gauge bosons are induced at low energies through the radiative corrections. In this scenario the Higgs boson can be arbitrarily heavy, interacting with the Standard Model fields arbitrarily weakly. No violation of unitarity in the scattering of longitudinal electroweak bosons occurs, since they become unphysical degrees of freedom at energies Λ ~ TeV.

scholarly journals Impacts of multi-Higgs on the ρ parameter, decays of a neutral Higgs to WW and ZZ, and a charged Higgs to WZ

2018 ◽  
Vol 33 (26) ◽  
pp. 1850152 ◽  
Author(s):  
Jian-Yong Cen ◽  
Jung-Hsin Chen ◽  
Xiao-Gang He ◽  
Jhih-Ying Su
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
New Physics ◽  
Tree Level ◽  
The Standard Model ◽  
Charged Higgs ◽  
Crucial Information ◽  
Custodial Symmetry

In the Standard Model (SM), the [Formula: see text] parameter is equal to 1 and the ratio [Formula: see text] of Higgs [Formula: see text] and Higgs [Formula: see text] is also equal to 1 at the tree level. When going beyond the SM with more than one type of Higgs representations, these quantities may be different from the SM predictions which can provide crucial information about new physics. There may also exist a certain charged Higgs [Formula: see text] decays into a [Formula: see text] and a [Formula: see text]. Imposing a custodial symmetry can force the parameter [Formula: see text] to be equal to 1 with certain predictions for [Formula: see text] and [Formula: see text]. However, imposing [Formula: see text] without custodial symmetry may have different predictions. We show how differences arise and how to use experimental data to obtain information about the underlying physics in a model with the SM, plus a real and a complex [Formula: see text] triplet.

A COMPLETELY UNUNIFIED ELECTROWEAK MODEL

1991 ◽  
Vol 06 (13) ◽  
pp. 1185-1193 ◽  
Author(s):  
DEBAJYOTI CHOUDHURY
Keyword(s):  
Standard Model ◽  
Tree Level ◽  
Matrix Elements ◽  
Neutral Currents ◽  
Gauge Bosons ◽  
Anomaly Cancellation ◽  
Neutrino Sector ◽  
Flavor Changing ◽  
The Standard Model ◽  
Electroweak Model

We construct a “fully ununified” electroweak model in which the quarks and leptons transform under separate SU (2) L ⊗ U (1)Y groups. There are two charged and three massive neutral gauge bosons, the lightest of which are similar to the standard model particles. Anomaly cancellation does not lead to any tree level flavor changing neutral currents except in the neutrino sector. A variant that naturally leads to a hierarchy in the Kobayashi-Maskawa matrix elements is proposed.

scholarly journals Renormalization group equations of Higgs-R2 inflation

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Yohei Ema ◽  
Kyohei Mukaida ◽  
Jorinde van de Vis
Keyword(s):  
Renormalization Group ◽  
Standard Model ◽  
Planck Scale ◽  
Energy Scale ◽  
Einstein Frame ◽  
Ricci Scalar ◽  
Minimal Coupling ◽  
Renormalization Group Equations ◽  
The Standard Model

Abstract We derive one- and two-loop renormalization group equations (RGEs) of Higgs-R2 inflation. This model has a non-minimal coupling between the Higgs and the Ricci scalar and a Ricci scalar squared term on top of the standard model. The RGEs derived in this paper are valid as long as the energy scale of interest (in the Einstein frame) is below the Planck scale. We also discuss implications to the inflationary predictions and the electroweak vacuum metastability.

scholarly journals HIDING THE EXISTENCE OF A FAMILY SYMMETRY IN THE STANDARD MODEL

2005 ◽  
Vol 20 (36) ◽  
pp. 2767-2774 ◽  
Author(s):  
ERNEST MA
Keyword(s):  
Standard Model ◽  
Neutrino Mass ◽  
Mass Matrix ◽  
Higgs Sector ◽  
Higgs Doublet ◽  
Neutrino Mass Matrix ◽  
Tree Level ◽  
Family Symmetry ◽  
The Standard Model

If a family symmetry exists for the quarks and leptons, the Higgs sector is expected to be enlarged to be able to support the transformation properties of this symmetry. There are, however, three possible generic ways (at tree level) of hiding this symmetry in the context of the Standard Model with just one Higgs doublet. All three mechanisms have their natural realizations in the unification symmetry E6 and one in SO (10). An interesting example based on SO (10)×A4 for the neutrino mass matrix is discussed.

Sign in / Sign up

Export Citation Format

Share Document