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Ernest Ma

Publications and source records attributed to Ernest Ma.

At least 361 records · Page 20Linked to original sources
arXiv1995

Model of Four Light Neutrinos in the Light of All Present Data

Motivated by existing and recent data on possible neutrino oscillations, we propose a model of four light neutrinos ($ν_e, ν_μ, ν_τ$, and a singlet $ν_S$) with a pattern of masses and mixing derivable from a $Z_5$ discrete symmetry and the seesaw mechanism. Atmospheric neutrino oscillations occur between $ν_μ$ and $ν_τ$ as pseudo-Dirac partners; whereas solar neutrino oscillations occur between $ν_e$ and $ν_S$, a linear combination of which is massless. Additional oscillations may occur between $ν_e$ and $ν_μ$ to account for the recent observation of the LSND (Liquid Scintillator Neutrino Detector) experiment.

hep-ph↗
arXiv1995

Correlated Neutrino Oscillations

In solar neutrino oscillations, if $ν_e$ has a significant third massive component, the allowed parameter space in $Δm^2$ and $\sin^2 2 θ$ for the first two components is shown to be greatly increased. This third component may be correlated to atmospheric neutrino oscillations, as shown in a specific predictive seesaw model of the $3 \times 3$ neutrino mass matrix. Possible variations to include the recent LSND results are briefly discussed.

hep-ph↗
arXiv1995

The $R_b$ Excess at LEP: Clue to New Physics at the TEVATRON?

If the $R_b$ excess at LEP is real, then any explanation in terms of renormalizable loop corrections leads to important new decay modes of the $t$ quark and suppresses the $t \to bW$ branching ratio. In the two-Higgs-doublet model, the branching ratio of $Z \to b \bar b$ + a light boson which decays itself predominantly into $b \bar b$ is at least of order $10^{-4}$.

hep-ph↗
arXiv1995

Possible Revelation of Seesaw Mass Pattern in Solar and Atmospheric Neutrino Data

Assuming the solar and atmospheric neutrino deficits to be due to neutrino oscillations, it is shown that the 3X3 mass matrix spanning the e, mu, and tau neutrinos may have already revealed a seesaw mass pattern. Also, this matrix is the natural reduction of a simple 5X5 seesaw mass matrix with one large scale, the 4X4 reduction of which predicts that a fourth neutrino would mix with the e and mu neutrinos in such a way that oscillations between them may occur just within the detection capability of the LSND (Liquid Scintillator Neutrino Detector) experiment.

hep-ph↗
arXiv1994

Two-Doublet Higgs Structure at the Electroweak Energy Scale

The existence of supersymmetry above a few TeV and that of two Higgs doublets at the electroweak energy scale do not necessarily result in the minimal supersymmetric standard model (MSSM). An interesting counter example is given with m_h < 2^{1/2} m_W + radiative corrections = 145 GeV instead of m_h < m_Z + radiative corrections = 128 GeV in the MSSM.

hep-ph↗
arXiv1994

Left-Right Gauge Symmetry at the TeV Energy Scale

Two first examples beyond the standard model are given which exhibit left-right symmetry (g_L = g_R) and supersymmetry at a few TeV, together with gauge-coupling unification at around 10^{16} GeV.

hep-ph↗
arXiv1994

Simple Radiative Neutrino Mass Matrix for Solar and Atmospheric Oscillations

A simple 3 X 3 neutrino mass matrix is proposed to accommodate both the solar and atmospheric neutrino deficits. This scenario can be realized naturally by a radiative mechanism for the generation of neutrino masses. It also goes together naturally with electroweak baryogenesis and cold dark matter in a specific model.

hep-ph↗
arXiv1994

Scalar Mass Bounds in Two Supersymmetric Extended Electroweak Gauge Models

In two recently proposed supersymmetric extended electroweak gauge models, the reduced Higgs sector at the 100-GeV energy scale consists of only two doublets, but they have quartic scalar couplings different from those of the minimal supersymmetric standard model. In the SU(2) X SU(2) X U(1) model, there is an absolute upper bound of about 145 GeV on the mass of the lightest neutral scalar boson. In the SU(3) X U(1) model, there is only a parameter-dependent upper bound which formally goes to infinity in a particular limit

hep-ph↗
arXiv1994

Unifiable Supersymmetric Left-Right Model with E_6 Particle Content

A new supersymmetric gauge model is proposed with particle content chosen only from the 27 and 27* representations of E_6. The gauge symmetry SU(3) X SU(2)_L X SU(2)_R X U(1) is realized at the TeV energy scale and the gauge couplings converge to a single value at around 10^{16} GeV. A discrete Z_4 X Z_2 symmetry leads to a generalized definition of lepton number and ensures the absence of tree-level flavor-changing neutral-current interactions at the electroweak energy scale.

hep-ph↗
arXiv1994

Neutrino Decay in the Doublet Majoron Model

A new Majoron model is presented within the framework of the seesaw mechanism. Its Higgs sector consists of only doublet representations and the lepton-number violation takes place at the same scale of the electroweak symmetry breaking. This model is different from the singlet- or triplet-Majoron model in several respects: it is free from the \(ρ\)-parameter constraint and it provides moderately fast neutrino decay, but the constraint from the stellar cooling of red giants is satisfied only with an imposed approximate symmetry. A \(τ\) neutrino as heavy as 10 MeV is possible in this model despite various cosmological and astrophysical constraints.

hep-ph↗
arXiv1994

Left-Right Symmetry and Supersymmetric Unification

The existence of an SU(3) X SU(2)_L X SU(2)_R X U(1) gauge symmetry with g_L = g_R at the TeV energy scale is shown to be consistent with supersymmetric SO(10) grand unification at around 1O^{16} GeV if certain new particles are assumed. The additional imposition of a discrete Z_2 symmetry leads to a generalized definition of R parity as well as highly suppressed Majorana neutrino masses. Another model based on SO(10) X SO(10) is also discussed.

hep-ph↗
arXiv1993

Natural Conservation of R Parity in Supersymmetry

Since baryon number B and lepton number L are no longer automatically conserved once the standard model is extended to include supersymmetry, the usually assumed conservation of R parity is an imposed condition. For a more satisfactory realization of supersymmetry, we propose here a new model which conserves R automatically. It is unifiable under SO(14) and has exotic fermions at the 100 GeV scale. One important result is the enhancement of the Higgs-boson decay rates into two gluons and into two photons by factors of 25 and 15 respectively.

hep-ph↗
arXiv1993

The Tau Neutrino as the Lightest Supersymmetric Particle

Given the conservation of baryon number as well as electron and muon numbers, all present data can be explained without the need of a conserved quantum number for the tau lepton and its neutrino. A supersymmetric extension of the standard model naturally allows for such a scenario. One consequence is that the tau neutrino becomes the lightest supersymmetric particle.

hep-ph↗
arXiv1993

New Supersymmetric Electroweak Gauge Model with Natural Baryon-Number Conservation

Baryon number (B) is automatically conserved in the standard SU(2) X U(1) electroweak gauge model, but not in its supersymmetric extension where it must be imposed as an extra condition. This undesirable feature is avoided in the conventional left-right supersymmetric extension, but then flavor-changing neutral currents (FCNC) are not naturally suppressed. A new version is proposed with automatic B conservation as well as FCNC suppression (except for u quarks through scalar exchange).

hep-ph↗
arXiv1993

Supersymmetric SU(3) X U(1) Gauge Model: Higgs Structure at the Electroweak Scale

We consider a supersymmetric version of the recently proposed SU(3) X U(1) extended gauge model. We show that it is possible to have only two Higgs doublets at the SU(2) X U(1) energy scale but they are not those of the minimal supersymmetric standard model. In particular, the upper bound on the lightest scalar boson of this model is $4 M_Z \sin θ_W$ at tree level and goes up to 189 GeV after radiative corrections.

hep-ph↗