703 research outputs found

    From Neutrino Masses to Proton Decay

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    Current theoretical and experimental issues are reviewed in the light of the recent SuperKamiokande discovery. By using quark-lepton symmetries, derived from Grand Unification and/or string theories, we show how to determine the necessary neutrino parameters. In addition, the seesaw neutrino masses set the scale for the proton decay operators by ``measuring'' the standard model cut-off. The SuperKamiokande values suggest that proton decay is likely to be observed early in the XXIst Century.Comment: Invited Talk at the Workshop on the Next generation Nucleon decay and Neutrino detector (NNN99), September 23-25, 1999. Latex, 9 page

    Neutrinos: Windows to Planck Physics

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    After recalling some elegant contributions of the late Freydoon Mansouri, we turn to neutrino physics and use a {\it modicum} of grand unification to relate quark and lepton mixing matrices. We advocate an expansion for the MNS matrix, {\it \`a la} Wolfenstein, and argue that in a wide class of models, θ13\theta_{13} is a Cabibbo mixing effect. Also the large neutrino mixing angles reflect the mass patterns of the right-handed neutrinos near the Planck scale, and provide evidence for family structure at that scale.Comment: COntribution to Quantum Theory and Symmetries COnference, Univ of Cincinatti, October 2003; Latex, 11 page

    Mass Hierarchies from Anomalies: a Peek Behind the Planck Curtain

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    The masses of quarks and leptons suggest a strong hierarchical structure. We argue that their patterns can be reproduced through the introduction of a new Abelian symmetry. The data suggest that this symmetry is anomalous. We suggest that the cancellation of its anomalies occur through the Green-Schwarz mechanism. An important check of this idea is that it links the Weinberg angle to a mass ratio of the elementary fermions. The Green-Schwarz mechanism occurs naturally in many superstring compactifications, and produces a small parameter, which we use to determine the quark mass hierarchy. We show that hierarchy and mixings among the chiral fermions is a consequence of the Green-Schwarz mechanism. We present several models where this idea is realized.Comment: Based on a talk delivered in the honor of Professor K. Kikkawa's 60th birthday, December 1995, Osaka, Japan. Latex, 15 pages, macros include

    Dirac Equations, Light Cone Supersymmetry, and Superconformal Algebras

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    After a brief historical survey that emphasizes the role of the algebra obeyed by the Dirac operator, we examine an algebraic Dirac operator associated with Lie algebras and Lie algebra cosets. For symmetric cosets, its ``massless'' solutions display non-relativistic supersymmetry, and can be identified with the massless degrees of freedom of some supersymmetric theories: N=1 supergravity in eleven dimensions (M-theory), type IIB string theory in ten and four dimensions, and in four dimensions, N=8 supergravity, N=4 super-Yang-Mills, and the N=1 Wess-Zumino multiplet. By generalizing this Dirac operator to the affine case, we generate superconformal algebras associated with cosets g/h{\bf g}/\bf h, where h\bf h contains the {\it space} little group. Only for eleven dimensional supergravity is h\bf h simple. This suggests, albeit in a non-relativistic setting, that these may be the limit of theories with underlying two-dimensional superconformal structure.Comment: 19 pages, latex, [sprocl]. Contributed article to Golfand's Memorial Volume, M. Shifman ed., World Scientifi
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