arXiv subjects

Ernest Ma

Publications and source records attributed to Ernest Ma.

At least 145 records · Page 8Linked to original sources

arXiv2011

Observable T_7 Lepton Flavor Symmetry at the Large Hadron Collider

More often than not, models of flavor symmetry rely on the use of nonrenormalizable operators (in the guise of flavons) to accomplish the phenomenologically successful tribimaximal mixing of neutrinos. We show instead how a simple renormalizable two-parameter neutrino mass model of tribimaximal mixing can be constructed with the non-Abelian discrete symmetry T_7 and the gauging of B-L. This is also achieved without the addition of auxiliary symmetries and particles present in almost all other proposals. Most importantly, it is verifiable at the Large Hadron Collider.

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arXiv2011

Observable Lepton Flavor Symmetry at LHC

I discuss a model of lepton flavor symmetry based on the non-Abelian finite group T(7) and the gauging of B-L, which has a residual Z(3) symmetry in the charged-lepton Yukawa sector, allowing it to be observable at the Large Hadron Collider (LHC) from the decay of the new Z' gauge boson of this model to a pair of scalar bosons which the unusual highly distinguishable final states tau(-)tau(-)mu(+)e(+).

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arXiv2010

Neutral SU(2) Gauge Extension of the Standard Model and a Vector-Boson Dark-Matter Candidate

If the standard model of particle interactions is extended to include a neutral SU(2)_N gauge factor, with SU(3)_C x SU(2)_L x U(1)_Y x SU(2)_N embedded in E_6 or [SU(3)]^3, a conserved generalized R parity may appear. As a result, we have the first example of a possible dark-matter candidate X_1 which is a non-Abelain vector boson. Using current data, its mass is predicted to be less than about 1 TeV. The associated Z' of this model, as well as some signatures of the Higgs sector, should then be observable at the LHC (Large Hadron Collider).

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arXiv2010

Dark Left-Right Model: CDMS, LHC, etc

The Standard Model of particle interactions is extended to include fermion doublets (n,e)_R transforming under the gauge group SU(2)_R such that n is a Dirac scotino (dark-matter fermion), with odd R parity. Based on recent CDMS data, it is shown how this new dark left-right model (DLRM2) favors a Z' gauge boson at around 1 or 2 TeV and be observable at the LHC. The new W_R gauge bosons may also contribute significantly to lepton-flavor-changing processes such as mu to e gamma and mu-e conversion in a nucleus or muonic atom.

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arXiv2010

Quark and Lepton Flavor Triality

Motivated by the success of A_4 in explaining neutrino tribimaximal mixing, and its approximate residual Z_3 symmetry in the quark and charged-lepton sectors, the notion of "flavor triality" is proposed. Under this hypothesis, certain processes such as tau+ to mu+mu+e- and tau+ to e+e+mu- are favored, but tau+ to mu+e+e- and mu+ to e+e+e- are disfavored. Similarly, B0 to tau+e- is favored, but B0 to tau-e+ is disfavored.

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arXiv2010

Effective Two Higgs Doublets in Nonminimal Supersymmetric Models

The Higgs sectors of supersymmetric extensions of the Standard Model have two doublets in the minimal version (MSSM), and two doublets plus a singlet in two others: with (UMSSM) and without (NMSSM) an extra U(1)'. A very concise comparison of these three models is possible if we assume that the singlet has a somewhat larger breaking scale compared to the electroweak scale. In that case, the UMSSM and the NMSSM become effectively two-Higgs-doublet models (THDM), like the MSSM. As expected, the mass of the lightest CP-even neutral Higgs boson has an upper bound in each case. We find that in the NMSSM, this bound exceeds not very much that of the MSSM, unless tan(beta) is near one. However, the upper bound in the UMSSM may be substantially enhanced.

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arXiv2010

Pseudo-Majoron as Dark Matter

We consider the singlet Majoron model with softly broken lepton number. This model contains three right-handed neutrinos and a singlet scalar besides the standard model fields. The real part of the singlet scalar develops a vacuum expectation value to generate the lepton number violation for seesaw and leptogenesis. The imaginary part of the singlet scalar becomes a massive pseudo-Majoron to be a dark matter candidate with testability by colliders, direct detection experiments and neutrino observations.

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arXiv2010

Gauged B-x_i L origin of R parity and its implications

Gauged B-L is a popular candidate for the origin of the conservation of R parity, i.e. R = (-)^{3B+L+2j}, in supersymmetry, but it fails to forbid the effective dimension-five terms arising from the superfield combinations QQQL, uude, and uddN, which allow the proton to decay. Changing it to B-x_i L, where x_e+x_μ+x_τ=3 (with x_i not equal to 1) for the three families, would forbid these terms while still serving as a gauge origin of R parity. We show how this is achieved in two minimal models with realistic neutrino mass matrices, and discuss their phenomenological implications.

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arXiv2010

Utilitarian Supersymmetric Gauge Model of Particle Interactions

A remarkable U(1) gauge extension of the supersymmetric standard model was proposed eight years ago. It is anomaly-free, has no mu term, and conserves baryon and lepton numbers automatically. The phenomenology of a specific version of this model is discussed. In particular, leptoquarks are predicted, with couplings to the heavy singlet neutrinos, the scalar partners of which may be components of dark matter. The Majorana neutrino mass matrix itself may have two zero subdeterminants.

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arXiv2010

Unifiable Supersymmetric Dark Left-Right Gauge Model

The recently proposed dark left-right gauge model, with Z' and W_R bosons at the TeV scale, is shown to have a simple supersymmetric extension which is unifiable. Its one-loop gauge-coupling renormalization-group equations are shown to have identical solutions to those of the minimal supersymmetric standard model. It also has a rich dark sector, with at least three stable particles.

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arXiv2010

Gauged B-L Leptogenesis

We propose a new leptogenesis scenario in a gauged $B-L$ model with supersymmetry at the TeV energy scale. Instead of relying on the very small Yukawa couplings of the singlet neutrinos $N^c$ to generate the observed baryon asymmetry of the Universe, which requires a very large resonance enhancement, their $B-L$ gauge interactions are invoked. Successful leptogenesis is then possible if a particular scalar bilinear $\tilde N^c \tilde N^c$ term is disallowed.

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arXiv2010

Bound on Z' Mass from CDMS II in the Dark Left-Right Gauge Model II

With the recent possible signal of dark matter from the CDMS II experiment, the Z' mass of a new version of the dark left-right gauge model (DLRM II) is predicted to be at around a TeV. As such, it has an excellent discovery prognosis at the operating Large Hadron Collider.

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arXiv2010

Left-Handed Neutrinos and Right-Handed Scotinos

The Standard Model of particle interactions is extended to include fermion doublets (n,e)_R transforming under the gauge group SU(2)_R such that n is a scotino (dark-matter fermion), with odd R parity. This dark left-right model (DLRM) treats neutrinos and scotinos in parallel, and has interesting phenomenology at the Large Hadron Collider (LHC).

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arXiv2010

Dark Left-Right Gauge Model: SU(2)_R Phenomenology

In the recently proposed dark left-right gauge model of particle interactions, the left-handed fermion doublet $(ν,e)_L$ is connected to its right-handed counterpart $(n,e)_R$ through a scalar bidoublet, but $ν_L$ couples to $n_R$ only through $ϕ_1^0$ which has no vacuum expectation value. The usual R parity, i.e. $R = (-)^{3B+L+2j}$, can be defined for this nonsupersymmetric model so that both $n$ and $Φ_1$ are odd together with $W_R^\pm$. The lightest $n$ is thus a viable dark-matter candidate (scotino). Here we explore the phenomenology associated with the $SU(2)_R$ gauge group of this model, which allows it to appear at the TeV energy scale. The exciting possibility of $Z' \to 8$ charged leptons is discussed.

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arXiv2009

Neutrino Condensate as Origin of Dark Energy

We propose a new solution to the origin of dark energy. We suggest that it was created dynamically from the condensate of a singlet neutrino at a late epoch of the early Universe through its effective self interaction. This singlet neutrino is also the Dirac partner of one of the three observed neutrinos, hence dark energy is related to neutrino mass. The onset of this condensate formation in the early Universe is also related to matter density and offers an explanation of the coincidence problem of why dark energy (70%) and total matter (30%) are comparable at the present time. We demonstrate this idea in a model of neutrino mass with (right-handed) singlet neutrinos and a singlet scalar.

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arXiv2009

Asymmetric Higgs Sector and Neutrino Mass in an SU(2)_R Model

The asymmetric Higgs sector of one $SU(2)_L \times SU(2)_R$ bidoublet $(ϕ_1^0,ϕ_1^-;ϕ_2^+,ϕ_2^0)$ and one $SU(2)_R$ doublet [but no $SU(2)_L$ doublet] is considered in a nonsupersymmetric left-right extension of the standard model (SM) of particle interactions. The inverse seesaw mechanism for neutrino mass is naturally implemented with the addition of fermion singlets, allowing thereby the possibility of breaking $SU(2)_R$ at the TeV scale. In the limit $v_2 = < ϕ_2^0 > = 0$, the unavoidable flavor-changing neutral Higgs couplings to quarks are studied and shown to be naturally suppressed in $K-\bar{K}$ and $B-\bar{B}$ mixing, as well as in $b \to s γ$. All particles are consistent with having masses less than 1 TeV, and could be observable at the Large Hadron Collider (LHC).

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arXiv2009

Cosmic e^\pm, \bar p, γand neutrino rays in leptocentric dark matter models

Dark matter annihilation is one of the leading explanations for the recently observed $e^\pm$ excesses in cosmic rays by PAMELA, ATIC, FERMI-LAT and HESS. Any dark matter annihilation model proposed to explain these data must also explain the fact that PAMELA data show excesses only in $e^\pm$ spectrum but not in anti-proton. It is interesting to ask whether the annihilation mode into anti-proton is completely disallowed or only suppressed at low energies. Most models proposed have negligible anti-protons in all energy ranges. We show that the leptocentric $U(1)_{B-3L_i}$ dark matter model can explain the $e^\pm$ excesses with suppressed anti-proton mode at low energies, but at higher energies there are sizable anti-proton excesses. Near future data from PAMELA and AMS can provide crucial test for this type of models. Cosmic $γ$ ray data can further rule out some of the models. We also show that this model has interesting cosmic neutrino signatures.

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arXiv2009

Symbiotic Symmetries of the Two-Higgs-Doublet Model

The new phenomenon of symbiotic symmetries is described in the context of the Two-Higgs-Doublet Model (THDM). The quartic potential has two or more separate sectors with unequal symmetries, but these unequal symmetries persist even though the different sectors are renormalized by one another. We discuss all such symmetries of the THDM, consistent with the SU(2) x U(1) gauge interactions, using the Pauli formalism.

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