Measuring neutrino masses with supernova neutrinos

A new method to study the effects of neutrino masses on a supernova neutrino signal is proposed. The method relies exclusively on the analysis of the full statistics of neutrino events, it is independent of astrophysical assumptions, and does not require the observation of any additional phenomenon to trace possible delays in the neutrino arrival times. A statistics of several thousands of events as could be collected by SuperKamiokande, would allow to explore a neutrino mass range somewhat below 1eV.Comment: 3 pages; contribution to the proceedings of X Marcel Grossmann Meeting, Rio de Janeiro, 20-26 July 200

Effects of a general set of interactions on neutrino propagation in matter

This talk is based on the article hep-ph/9903517 written in collaboration with Sven Bergmann and Yuval Grossman. An analysis of the effective potential for neutrino propagation in matter, assuming a generic set of Lorentz invariant non-derivative interactions is presented. In addition to vector and axial vector couplings, also tensor interactions can give coherent effects if the medium is polarized, and the components of a tensor potential transverse to the direction of neutrino propagation can induce a neutrino spin-flip.Comment: 7 pages; plenary talk given at COSMO-99, Trieste, Italy, Sept 27 - Oct 2, 199

Naturally large Yukawa hierarchies

The spontaneous breaking of the $SU(3)^5$ quark/lepton flavor symmetry by means of three multiplets of scalar `Yukawa fields' admits vacua with one O(1) and two vanishing vacuum expectation values (vevs) for each multiplet. If the number of generations is equal to three, and only in this case, the vanishing vevs are lifted to exponentially suppressed entries by the inclusion of symmetry invariant logarithmic terms. A strong hierarchy for the Yukawa couplings and a quark mixing matrix that approaches a diagonal form are obtained in a natural way from O(1) parameters. This scenario provides a concrete realization of the minimal flavor violation hypothesis.Comment: 8 pages. Added two references. Section 2a and 3 revised. Results unchange

“Not Like a Big Gap, Something We Could Handle”: Facilitating Shifts in Paradigm in the Supervision of Mathematics Graduates upon Entry into Mathematics Education

Mathematics is the discipline that a significant majority of most incoming researchers in mathematics education have prior qualifications and experience in. Upon entry into the field of mathematics education research, these newcomers–often students on a postgraduate programme in mathematics education–need a broadened understanding on how to read, converse, write and conduct research in the largely unfamiliar territory of mathematics education. The intervention into the practices of post-graduate teaching and supervision in the field of mathematics education that I describe here aims at fostering this broadened understanding and thus facilitating newcomers’ participation in the practices of the mathematics education research community. Here I outline the theoretical underpinnings of the intervention and exemplify one of its parts (an Activity Set designed to facilitate incoming students’ engagement with the mathematics education research literature). I supplement the discussion of the intervention with comments sampled from student interview and student written evaluation data as well as observations of the activities’ implementation. The main themes touched upon include: learning how to identify appropriate mathematics education literature; reading increasingly more complex writings in mathematics education; coping with the complexity of literate mathematics education discourse; working towards a contextualised understanding of literate mathematics education discourse. I conclude with indicating the directions that the intervention, and its evaluation, is currently taking and a brief discussion of broader implications, theoretical as well as concerning the supervision and teaching of post-graduate students in mathematics education

Quark Yukawa pattern from spontaneous breaking of flavour SU(3)3SU(3)^3

A $SU(3)_Q \times SU(3)_u \times SU(3)_d$ invariant scalar potential breaking spontaneously the quark flavour symmetry can explain the standard model flavour puzzle. The approximate alignment in flavour space of the vacuum expectation values of the up and down `Yukawa fields' results as a dynamical effect. The observed quark mixing angles, the weak CP violating phase, and hierarchical quark masses can be all reproduced at the cost of introducing additional (auxiliary) scalar multiplets, but without the need of introducing hierarchical parameters.Comment: 8 pages. Contribution to the proceedings of the 10th Simposio Latinoamericano de F\'isica de Altas Energ\'ias (X SILAFAE) - Ruta N, Medell\'in, Colombia, November 24-28 201