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Search: authors:"Kei Yagyu"

10 papers found.
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Phenomenology of E 6-inspired leptophobic Z ′ boson at the LHC

We study collider phenomenology of a leptophobic Z ′ boson existing in eight scenarios of the E 6 grand unified theory, differing in particle embeddings. We first review the current bound on the Z ′ mass m Z′ based upon the LHC data of pp → \( t\overline{t} \) process at 8 TeV collisions with an integrated luminosity of 19.6 fb−1. Most scenarios have a lower bound of about 1 TeV...

Leptophobic Z′ in models with multiple Higgs doublet fields

We study the collider phenomenology of the leptophobic Z′ boson from an extra U(1)′ gauge symmetry in models with N -Higgs doublet fields. We assume that the Z′ boson at tree level has (i) no Z-Z′ mixing, (ii) no interaction with the charged leptons, and (iii) no flavour-changing neutral current. Under such a setup, it is shown that in the N = 1 case, all the U(1)′ charges of...

Flavour dependent gauged radiative neutrino mass model

We propose a one-loop induced radiative neutrino mass model with anomaly free flavour dependent gauge symmetry: μ minus τ symmetry U(1) μ−τ . A neutrino mass matrix satisfying current experimental data can be obtained by introducing a weak isospin singlet scalar boson that breaks U(1) μ−τ symmetry, an inert doublet scalar field, and three right-handed neutrinos in addition to the...

Lepton-specific two Higgs doublet model as a solution of muon g − 2 anomaly

AbstractWe discuss the Type-X (lepton-specific) two Higgs doublet model as a solution of the anomaly of the muon g − 2. We consider various experimental constraints on the parameter space such as direct searches for extra Higgs bosons at the LEP II and the LHC Run-I, electroweak precision observables, the decay of B s → μ+μ−, and the leptonic decay of the tau lepton. We find that...

Enhancement of the H ± W ∓ Z vertex in the three scalar doublet model

We compute one-loop induced trilinear vertices with physical charged Higgs bosons H ± and ordinary gauge bosons, i.e., H ± W ∓ Z and H ± W ∓ γ, in the model with two active plus one inert scalar doublet fields under a Z 2(unbroken) × \( {\tilde{Z}}_2 \)(softly-broken) symmetry. The Z 2 and \( {\tilde{Z}}_2 \) symmetries are introduced to guarantee the stability of a dark matter...

CP violating Two-Higgs-Doublet Model: constraints and LHC predictions

Two-Higgs-Doublet Models (2HDMs) are amongst the simplest extensions of the Standard Model. Such models allow for tree-level CP Violation (CPV) in the Higgs sector. We analyse a class of CPV 2HDM (of Type-I) in which only one of the two Higgs doublets couples to quarks and leptons, avoiding dangerous Flavour Changing Neutral Currents. We provide an up to date and comprehensive...

LHC phenomenology of composite 2-Higgs doublet models

We investigate the phenomenology of Composite 2-Higgs doublet models (C2HDMs) of various Yukawa types based on the global symmetry breaking \(SO(6)\rightarrow SO(4)\times SO(2)\). The kinetic part and the Yukawa Lagrangian are constructed in terms of the pseudo Nambu–Goldstone Boson (pNGB) matrix and a 6-plet of fermions under SO(6). The scalar potential is assumed to be the same...

Muon specific two-Higgs-doublet model

We investigate a new type of a two-Higgs-doublet model as a solution of the muon g − 2 anomaly. We impose a softly-broken Z 4 symmetry to forbid tree level flavor changing neutral currents in a natural way. This Z 4 symmetry restricts the structure of Yukawa couplings. As a result, extra Higgs boson couplings to muons are enhanced by a factor of tan β, while their couplings to...

Extracting the mass scale of a second Higgs boson from a deviation in h(125) couplings

We investigate the correlation between a possible deviation in the discovered Higgs boson h(125) couplings from the Standard Model prediction and the mass scale (M 2nd) of the next-to-lightest Higgs boson in models with non-minimal Higgs sectors. In particular, we comprehensively study a class of next-to-minimal Higgs sectors which satisfy the electroweak ρ parameter to be one at...

A concrete composite 2-Higgs doublet model

Abstract We consider a Composite Higgs Model (CHM) with two isospin doublet Higgs fields arising as pseudo Nambu-Goldstone bosons from a SO(6) → SO(4) × SO(2) breaking. The main focus of this work is to explicitly compute the properties of these Higgses in terms of the fundamental parameters of the composite sector such as masses, Yukawa and gauge couplings of the new spin-1 and...