A Minimal See-Saw Model for Hierarchical Neutrino Masses with Large Mixing

The atmospheric and solar neutrino oscillation data suggest hierarchical neutrino masses with at least one large mixing. The simplest see-saw models for reconciling the two features are U(1) extensions of the SM with flavour dependent gauge charges. I discuss a minimal model of this type containing two heavy right-handed neutrinos, which have normal Dirac couplings to $\nu_\mu$ and $\nu_\tau$ but suppressed ones to $\nu_e$. It can naturally account for the large (small) mixing solutions to the atmospheric (solar) neutrino oscillation data.Comment: 6 pages, Latex, Invited Talk at the 6th San Miniato Topical Seminar on `Neutrino and Astroparticle Physics', to appear in Nuclear Physics B (Proc. Suppl.

Verifiable Radiative Seesaw Mechanism of Neutrino Mass and Dark Matter

A minimal extension of the Standard Model is proposed, where the observed left-handed neutrinos obtain naturally small Majorana masses from a one-loop radiative seesaw mechanism. This model has two candidates (one bosonic and one fermionic) for the dark matter of the Universe. It has a very simple structure and should be verifiable in forthcoming experiments at the Large Hadron Collider.Comment: 8 pages, 1 figur

Connection Between the Neutrino Seesaw Mechanism and Properties of the Majorana Neutrino Mass Matrix

If it can be ascertained experimentally that the 3X3 Majorana neutrino mass matrix M_nu has vanishing determinants for one or more of its 2X2 submatrices, it may be interpreted as supporting evidence for the theoretically well-known canonical seesaw mechanism. I show how these two things are connected and offer a realistic M_nu with two zero subdeterminants as an example.Comment: title changed, version to appear in PRD(RC

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.Comment: 7 pages, no figur

Reflecting in and on post-observation feedback in initial teacher training on certificate courses

This article examines evidence from two studies that concern the nature of post-observation feedback in certificate courses for teaching English to speakers of other languages. It uncovers the main characteristics of these meetings and asks whether there is evidence of reflection in these contexts. In considering reasons why making space for reflection is potentially difficult, the paper also examines the relationship and the role of assessment criteria and how these may impact on opportunities for reflection. The final part of the paper considers how a more reflective approach could be promoted in feedback conferences

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 $(\nu_e, \nu_\mu, \nu_\tau)$ 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.Comment: 9 pages, 1 figure, talk at TAUP 200

Dirac neutrino mass generation from dark matter

In 2006, a simple extension of the Standard Model was proposed in which neutrinos obtain radiative Majorana masses at one-loop level from their couplings with dark matter, hence the term "scotogenic," from the Greek "scotos" meaning darkness. Here an analogous mechanism for Dirac neutrino masses is discussed in a minimal model. In different ranges of the parameter space, various candidates for dark matter are possible. In particular, the lightest Dirac fermion which appears in the loop diagram generating neutrino mass can be a viable dark matter candidate. Such a possibility does not exist for the Majorana case. Realistic neutrino mixing in the context of $A_4$ is discussed. A possible supersymmetric extension is also briefly discussed.Comment: 17 pages, 2 figures; v3: version to appear in PR

Neutrino Mass Matrix from S_4 Symmetry

The cubic symmetry S_4 contains A_4 and S_3, both of which have been used to study neutrino mass matrices. Using S_4 as the family symmetry of a complete supersymmetric theory of leptons, it is shown how the requirement of breaking S_4 at the seesaw scale without breaking supersymmetry enforces a special form of the neutrino mass matrix which exhibits maximal nu_mu - nu_tau mixing as well as zero U_e3. In addition, (nu_e + nu_mu + nu_tau)/sqrt{3} is naturally close to being a mass eignestate, thus predicting tan^2 theta_12 to be near but not equal to 1/2.Comment: 11 pages, no figur