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Ernest Ma

Publications and source records attributed to Ernest Ma.

At least 271 records · Page 15Linked to original sources
arXiv2002

Pattern of the Approximate Mass Degeneracy of Majorana Neutrinos

In view of the recently reported evidence for a nonzero Majorana mass of the electron neutrino, together with the established phenomena of atmospheric and solar neutrino oscillations, the case of three nearly mass-degenerate Majorana neutrinos is now a distinct possibility. I show in this paper how a natural pattern of symmetry breaking in the recently proposed $A_4$ model of Majorana neutrino masses can accommodate the data on neutrino oscillations, resulting in the predictions $\sin^2 2 θ_{atm} = 1$ and $\sin^2 2 θ_{sol} = 2/3$.

hep-ph↗
arXiv2001

Anomalous Neutrino Interaction, Muon g-2, and Atomic Parity Nonconservation

We propose a simple unified description of two recent precision measurements which suggest new physics beyond the Standard Model of particle interactions, i.e. the deviation of $\sin^2 θ_W$ in deep inelastic neutrino-nucleon scattering and that of the anomalous magnetic moment of the muon. Our proposal is also consistent with a third precision measurement, i.e. that of parity nonconservation in atomic Cesium, which agrees with the Standard Model.

hep-ph↗
arXiv2001

Unified Supersymmetric Model of Naturally Small Dirac Neutrino Masses and the Axionic Solution of the Strong CP Problem

Using the particle content of the fundamental {27} supermultiplet of E_6, naturally small Dirac neutrino masses are obtained in the context of SU(3)_C times SU(2)_L times U(1)_Y times U(1)_{chi}, where U(1)_{chi} comes from the decomposition E_6 to SO(10) times U(1)_{psi}, then SO(10) to SU(5) times U(1)_{chi}. New observable consequences are predicted at the TeV scale. An axionic solution of the strong CP problem may be included at no extra cost.

hep-ph↗
arXiv2001

Verifiable Origin of Neutrino Mass at TeV Scale

The physics responsible for neutrino mass may reside at or below the TeV energy scale. The neutrino mass matrix in the $(ν_e, ν_μ, ν_τ)$ basis may then be deduced from future high-energy accelerator experiments. The newly observed excess in the muon anomalous magnetic moment may also be related.

hep-ph↗
arXiv2001

Muon g-2 and Neutrino Mass in a New Minimal Extension of the MSSM

If the one term $(\hat ν_e \hat μ- \hat e \hat ν_μ) \hat τ^c$ is added to the MSSM (Minimal Supersymmetric Standard Model) superpotential, the recently observed muon g--2 (anomalous magnetic moment) excess can be explained very simply by a light $\tilde ν_e$. If the soft symmetry-breaking terms $\hat ν_α\hat h_2^0 - \hat l_α\hat h_2^+$ are also added, realistic neutrino masses (with bimaximal mixing) are generated as well.

hep-ph↗
arXiv2001

Double Threefold Degeneracies for Active and Sterile Neutrinos

We explore the possibility that the 3 active (doublet) neutrinos have nearly degenerate masses which are split only by the usual seesaw mechanism from 3 sterile (singlet) neutrinos in the presence of a softly broken $A_4$ symmetry. We take the unconventional view that the sterile neutrinos may be light, i.e. less than 1 keV, and discuss some very interesting and novel phenomenology, including a connection between the LSND neutrino data and solar neutrino oscillations.

hep-ph↗
arXiv2001

Supersymmetric Model of Neutrino Mass and Leptogenesis with String-Scale Unification

Adjoint supermultiplets (1,3,0) and (8,1,0) modify the evolution of gauge couplings. If the unification of gauge couplings occurs at the string scale, their masses are fixed at around $10^{13}$ GeV. This scale coincides with expected gaugino condensation scale in the hidden sector $M_{string}^{2/3} m^{1/3}_{3/2} \sim 10^{13}$ GeV. We show how neutrino masses arise in this unified model which naturally explain the present atmospheric and solar neutrino data. The out-of-equilibrium decay of the superfield (1,3,0) at $10^{13}$ GeV may also lead to a lepton asymmetry which then gets converted into the present observed baryon asymmetry of the Universe.

hep-ph↗
arXiv2001

Neutrino Mass, Muon Anomalous Magnetic Moment, and Lepton Flavor Nonconservation

If the generating mechanism for neutrino mass is to account for both the newly observed muon anomalous magnetic moment as well as the present experimental bounds on lepton flavor nonconservation, then the neutrino mass matrix should be almost degenerate and the underlying physics be observable at future colliders. We illustrate this assertion in two specific examples, and show that $Γ(μ\to e γ)/m_μ^5$, $Γ(τ\to e γ)/m_τ^5$, and $Γ(τ\to μγ) /m_τ^5$ are in the ratio $(Δm^2)_{sol}^2/2$, $(Δm^2)_{sol}^2 /2$, and $(Δm^2)_{atm}^2$ respectively, where the $Δm^2$ parameters are those of solar and atmospheric neutrino oscillations and bimaximal mixing has been assumed.

hep-ph↗
arXiv2001

Supersymmetric Model of Muon Anomalous Magnetic Moment and Neutrino Masses

We propose the novel lepton-number relationship $L_τ= L_e + L_μ$, which is uniquely realized by the interaction $(\hat ν_e \hat μ- \hat e \hat ν_μ) \hat τ^c$ in supersymmetry and may account for a possibly large muon anomalous magnetic moment. Neutrino masses (with bimaximal mixing) may be generated from the spontaneous and soft breaking of this lepton symmetry.

hep-ph↗
arXiv2001

Light Unstable Sterile Neutrino

The three massless active (doublet) neutrinos may mix with two heavy and one \underline {light} sterile (singlet) neutrinos so that the induced masses and mixings among the former are able to explain the present data on atmospheric and solar neutrino oscillations. If the LSND result is also to be explained, one active neutrino mass eigenstate must mix with the light sterile neutrino. A specific model is proposed with the spontaneous and soft explicit breaking of a new global $U(1)_S$ symmetry so that a sterile neutrino will decay into an active antineutrino and a nearly massless pseudo-Majoron.

hep-ph↗
arXiv2001

Neutrino, Lepton, and Quark Masses in Supersymmetry

The recently proposed model of neutrino mass with no new physics beyond the TeV energy scale is shown to admit a natural and realistic supersymmetric realization, when combined with another recently proposed model of quark masses in the context of a softly broken U(1) symmetry. Four Higgs doublets are required, but two must have masses at the TeV scale. New characteristic experimental predictions of this synthesis are discussed.

hep-ph↗
arXiv2001

Phenomenology of the Neutrino-Mass-Giving Higgs Triplet and the Low-Energy Seesaw Violation of Lepton Number

Small realistic Majorana neutrino masses can be generated via a Higgs triplet $(ξ^{++}, ξ^+, ξ^0)$ without having energy scales larger than $M_*={\cal O}(1)$ TeV in the theory. The large effective mass scale $Λ$ in the well-known seesaw neutrino-mass operator $Λ^{-1} (LLΦΦ)$ is naturally obtained with $Λ\sim M_*^2/μ,$ where $μ$ is a {\it small} scale of lepton-number violation. In theories with large extra dimensions, the smallness of $μ$ is naturally obtained by the mechanism of ``shining'' if the number of extra dimensions $n\ge 3.$ We study here the Higgs phenomenology of this model, where the spontaneous violation of lepton number is treated as an external source from extra dimensions. The observable decays $ξ^{++} \to l_i^+l_j^+$ will determine directly the magnitudes of the $\{ij\}$ elements of the neutrino mass matrix. The decays $ξ^+ \to W^+ J^0$ and $ξ^0 \to Z J^0$, where $J^0$ is the massless Goldstone boson (Majoron), are also possible, but of special importance is the decay $ξ^0 \to J^0 J^0$ which provides stringent constraints on the allowed parameter space of this model. Based on the current neutrino data, we also predict observable rates of $μ-e$ conversion in nuclei.

hep-ph↗
arXiv2001

Softly Broken A_4 Symmetry for Nearly Degenerate Neutrino Masses

The leptonic Higgs doublet model of neutrino masses is implemented with an A_4 discrete symmetry (the even permutation of 4 objects or equivalently the symmetry of the tetrahedron) which has 4 irreducible representations: 1, 1', 1'', and 3. The resulting spontaneous and soft breaking of A_4 provides a realistic model of charged-lepton masses as well as a nearly degenerate neutrino mass matrix. Phenomenological consequences at and below the TeV scale are discussed.

hep-ph↗
arXiv2001

Quark Mass Matrices from a Softly Broken U(1) Symmetry

Assigning U(1) charges to the quarks of the standard model, and allowing one extra scalar doublet with m^2 > 0, the correct pattern of the up and down quark mass matrices is obtained, together with their charged-current mixing matrix.

hep-ph↗
arXiv2001

Global U(1) Invariance and Mass Scales in Supersymmetry

In a supersymmetric theory with global U(1) invariance, the spontaneous breaking of the latter without the breaking of supersymmetry is revisited in the case of the most general superpotential of 3 singlet superfields. The interesting possibility of having 2 hierarchical mass scales is pointed out, together with its consequences as applied to the axionic solution of the strong CP problem.

hep-ph↗
arXiv2001

Collider Verification of the Neutrino Mass Matrix in Two Scenarios

If the origin of neutrino mass is at the TeV energy scale, collider experiments may in fact {\it map out} all the elements of the $3 \times 3$ neutrino mass matrix, up to an overall scale. Two examples \cite{mrs,ma01} are discussed and one is related \cite{mr} to the muon anomalous magnetic moment.

hep-ph↗
arXiv2001

Making Neutrinos Massive with an Axion in Supersymmetry

The minimal supersymmetric standard model (MSSM) of particle interactions is extended to include three singlet (right-handed) neutrino superfields together with three other singlet superfields. The resulting theory is assumed to be invariant under an anomalous global U(1) (Peccei-Quinn) symmetry with one fundamental mass $m_2$. The soft breaking of supersymmetry at the TeV scale is shown to generate an axion scale $f_a$ of order $m_2$. Neutrino masses are generated by $f_a$ according to the usual seesaw mechanism.

hep-ph↗