Production of the triply charged leptons at the LHC

2018 ◽  
Vol 33 (30) ◽  
pp. 1850174
Author(s):  
Zhi-Cheng Liu ◽  
Chong-Xing Yue ◽  
Zhen-Hua Zhao
Keyword(s):  
Energy Scale ◽  
Neutrino Masses ◽  
Higher Dimension ◽  
Electroweak Interactions ◽  
Charged Fermion ◽  
Underlying Theory ◽  
Charged Leptons ◽  
Integrated Luminosity

The neutrino masses can be ascribed to some operators of higher dimension than the Weinberg operator, so that the energy scale of underlying theory can be lowered to an accessible level for the ongoing or upcoming colliders. We hereby consider an interesting model in this connection where quintuplet fermions with hypercharge [Formula: see text]2 are introduced and therefore the neutrino masses are produced by dimension-11 operators. These exotic fermions can be pairly produced at the LHC via electroweak interactions and subsequently decay to multiple leptons. We simulate the relevant signal and backgrounds of the triply charged fermion in this model, and give the needed integrated luminosity to observe such a particle at the 13 TeV LHC.

scholarly journals Lowering the scale of Pati-Salam breaking through seesaw mixing

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Matthew J. Dolan ◽  
Tomasz P. Dutka ◽  
Raymond R. Volkas
Keyword(s):  
Degrees Of Freedom ◽  
Tree Level ◽  
Charged Current ◽  
Meson Decay ◽  
Neutrino Masses ◽  
Down Quark ◽  
The Standard Model ◽  
Decay Widths ◽  
Left And Right ◽  
Charged Leptons

Abstract We analyse the experimental limits on the breaking scale of Pati-Salam extensions of the Standard Model. These arise from the experimental limits on rare-meson decay processes mediated at tree-level by the vector leptoquark in the model. This leptoquark ordinarily couples to both left- and right-handed SM fermions and therefore the meson decays do not experience a helicity suppression. We find that the current limits vary from $$ \mathcal{O} $$ O (80–2500) TeV depending on the choice of matrix structure appearing in the relevant three-generational charged-current interactions. We extensively analyse scenarios where additional fermionic degrees of freedom are introduced, transforming as complete Pati-Salam multiplets. These can lower the scales of Pati-Salam breaking through mass-mixing within the charged-lepton and down-quark sectors, leading to a helicity suppression of the meson decay widths which constrain Pati-Salam breaking. We find four multiplets with varying degrees of viability for this purpose: an SU(2)L/R bidoublet, a pair of SU(4) decuplets and either an SU(2)L or SU(2)R triplet all of which contain heavy exotic versions of the SM charged leptons. We find that the Pati-Salam limits can be as low as $$ \mathcal{O} $$ O (5–150) TeV with the addition of these four multiplets. We also identify an interesting possible connection between the smallness of the neutrino masses and a helicity suppression of the Pati-Salam limits for three of the four multiplets.

scholarly journals INSTANTON INDUCED CHARGED FERMION AND NEUTRINO MASSES IN A MINIMAL STANDARD MODEL SCENARIO FROM INTERSECTING D-BRANES

2009 ◽  
Vol 24 (32) ◽  
pp. 6035-6049 ◽  
Author(s):  
G. K. LEONTARIS
Keyword(s):  
Standard Model ◽  
Quark Mass ◽  
Majorana Neutrino ◽  
Neutrino Masses ◽  
Charged Fermion ◽  
Yukawa Couplings ◽  
Heavy Majorana Neutrino ◽  
Down Quark ◽  
Mass Matrices ◽  
Minimal Standard

String instanton Yukawa corrections from Euclidean D-branes are investigated in an effective Standard Model theory obtained from the minimal U (3)× U (2)× U (1) D-brane configuration. In the case of the minimal chiral and Higgs spectrum, it is found that superpotential contributions are induced by string instantons for the perturbatively forbidden entries of the up- and down-quark mass matrices. Analogous nonperturbative effects generate heavy Majorana neutrino masses and a Dirac neutrino texture with factorizable Yukawa couplings. For this latter case, a specific example is worked out where it is shown how this texture can reconcile the neutrino data.

scholarly journals FLAVOR MIXING, QUARK MASSES, NEUTRINO MASSES AND NEUTRINO OSCILLATIONS

2009 ◽  
Vol 24 (18n19) ◽  
pp. 3354-3358 ◽  
Author(s):  
H. FRITZSCH
Keyword(s):  
Neutrino Masses ◽  
Mixing Angle ◽  
Mixing Angles ◽  
Quark Masses ◽  
Mass Matrices ◽  
Mass Ratios ◽  
Flavor Mixing ◽  
Eigen Values ◽  
Charged Leptons ◽  
The Masses

We study a model for the mass matrices of the quarks and leptons. Two of the three flavor mixing angles of the quarks can be calculated in terms of the quark mass ratios. They agree very well with the experiments. We are able to relate the mass eigen values of the charged leptons and of the neutrinos to the mixing angles and can predict the masses of the neutrinos. We find a normal hierarchy -the masses are 0.004 eV, 0.01 eV and 0.05 eV. The atmospheric mixing angle is given by the mass ratios of the charged leptons and the neutrinos. We find 38 degrees, consistent with the experiments. The mixing element, connecting the first neutrino with the electron, is found to be 0.05.

scholarly journals AXIONIC EXTENSIONS OF THE SUPERSYMMETRIC STANDARD MODEL

2009 ◽  
Vol 24 (17) ◽  
pp. 1335-1342 ◽  
Author(s):  
ERNEST MA
Keyword(s):  
Dark Matter ◽  
Problem Solving ◽  
Standard Model ◽  
Supersymmetric Standard Model ◽  
Particle Physics ◽  
Theoretical Framework ◽  
Energy Scale ◽  
Neutrino Masses ◽  
New Particles

The Supersymmetric Standard Model is a benchmark theoretical framework for particle physics, yet it suffers from a number of deficiencies, the main one among which is the strong CP problem. Solving this with an axion in the context of selected new particles, it is shown in three examples that other problems go away automatically as well, resulting in (-)L and (-)3B conservation, viable combination of two dark-matter candidates, successful baryogenesis, seesaw neutrino masses, and verifiable experimental consequences at the TeV energy scale.

DERIVATION OF A NOVEL RELATION BETWEEN THE MASSES OF THE TOP-QUARK AND AN ELECTROWEAK SCALAR

2000 ◽  
Vol 15 (11) ◽  
pp. 1597-1612
Author(s):  
E. H. LEMKE
Keyword(s):  
Gauge Symmetry ◽  
Top Quark ◽  
Scalar Fields ◽  
Energy Scale ◽  
Coupling Constants ◽  
Spontaneous Breaking ◽  
Precision Data ◽  
Vector Bosons ◽  
Charged Leptons ◽  
The Masses

We start with generating the masses of the charged leptons by gap equations. Then we present analogous radiative masses of the electroweak vector-bosons. We derive them from the global SU (2)L× U (1) symmetry without making recourse to any scalar fields or spontaneous breaking of gauge symmetry. Nevertheless, we find the mixing angle relation [Formula: see text]. Moreover, we find that the radiatively generated masses of Z and W require the existence of a cutoff energy of the order of 1014 GeV, which is just the grand-unification energy scale. We then eliminate the cutoff by renormalizing the two coupling constants and arrive at a function between mW and m top if mZ, [Formula: see text] and sin 2θ eff are given. Comparison with the electroweak precision data shows that the predicted value of mW does reproduce the experimental data though the vacuum loops of the leptons, of the light quarks as well as of possible scalar particles have been ignored. Then, we introduce a doublet of scalar bosons to investigate its effect on the mW prediction. We fix its couplings to the photon, to W as well as Z by localizing SU (2)L× U (1). The radiative mZ and mW results interdict a spontaneous breaking of the gauge symmetry. So there are an elementary charged and neutral scalar field. Their masses are identical. We show that there is no radiative effect of these scalars on the masses of W and Z. However, the scalar fields affect the coupling constants and, by this, the relationship between mW and m top alters. We calculate the modifications and find a relatively small effect. It seems to be comparable in magnitude with the QCD-corrections of the loops of vacuum polarization. Substituting the experimental mW value, we get a relation between m top and m scalar . The mass of the top-quark is increasing with increasing m scalar . In the standard model, m top also increases with increasing m Higgs . The effect of the elementary scalar is however much weaker.

scholarly journals Radiative neutrino masses, lepton flavor mixing and muon g − 2 in a leptoquark model

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Di Zhang
Keyword(s):  
Neutrino Mass ◽  
Yukawa Coupling ◽  
Mass Matrix ◽  
Radiative Decays ◽  
Neutrino Masses ◽  
Reflection Symmetry ◽  
Lepton Flavor ◽  
Flavor Mixing ◽  
Charged Leptons ◽  
Scalar Leptoquarks

Abstract We propose a leptoquark model with two scalar leptoquarks $$ {S}_1\left(\overline{3},1,\frac{1}{3}\right) $$ S 1 3 ¯ 1 1 3 and $$ {\tilde{R}}_2\left(3,2,\frac{1}{6}\right) $$ R ˜ 2 3 2 1 6 to give a combined explanation of neutrino masses, lepton flavor mixing and the anomaly of muon g − 2, satisfying the constraints from the radiative decays of charged leptons. The neutrino masses are generated via one-loop corrections resulting from a mixing between S1 and $$ {\tilde{R}}_2 $$ R ˜ 2 . With a set of specific textures for the leptoquark Yukawa coupling matrices, the neutrino mass matrix possesses an approximate μ-τ reflection symmetry with (Mν)ee = 0 only in favor of the normal neutrino mass ordering. We show that this model can successfully explain the anomaly of muon g − 2 and current experimental neutrino oscillation data under the constraints from the radiative decays of charged leptons.

scholarly journals Almost Maximally Broken Permutation Symmetry for Neutrino Mass Matrix

1997 ◽  
Vol 12 (16) ◽  
pp. 1175-1184 ◽  
Author(s):  
Kyungsik Kang ◽  
Sin Kyu Kang ◽  
Jihn E. Kim ◽  
Pyungwon Ko
Keyword(s):  
Mass Matrix ◽  
Atmospheric Neutrino ◽  
Current Data ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Neutrino Mixing ◽  
Family Symmetry ◽  
Majorana Neutrinos ◽  
Charged Leptons ◽  
The Masses

Assuming three light neutrinos are Majorana particles, we propose mass matrix ansatz for the charged leptons and Majorana neutrinos with family symmetry S3 broken into S1 and S2, respectively. Each matrix has three parameters, which are fixed by measured charged lepton masses, differences of squared neutrino masses relevant to the solar and the atmospheric neutrino puzzles, and the masses of three light Majorana neutrinos as a candidate for hot dark matter with ∑|mν|~ 6 eV . The resulting neutrino mixing is compatible with the data for the current upper limit, <mνe> th <0.7 eV , of neutrino-less double beta decay experiments, and the current data for various types of neutrino oscillation experiments. One solution of our model predicts that νμ→ντ oscillation probability is about < 0.008 with Δm2 ~ 10-2 eV 2, which may not be accessible at CHORUS and other on-going experiments.

Sign in / Sign up

Export Citation Format

Share Document