Aspects of Neutrino Mass Matrices

After an Introduction briefly describing the rise and fall of the three-zero texture of the Zee model, we discuss still-allowed two-zero textures for the Majorana three-neutrino mass matrix. Finally, a model with two right-handed neutrinos and two Dirac texture zeros is described (FGY model) which can relate CP violation in leptogenesis to CP violation in long-baseline neutrino oscillations.Comment: 9 pages latex. Talk at Coral Gables 2003. Added reference

Position of First Doppler Peak

This talk describes an analytic calculation of the position of the first accoustic peak as a function of the matter density and the cosmological constant (work with Y.J. Ng and R. Rohm), agreeing with independent numerical studies. There is also discussion of supernovae observations and how together these approaches combine to suggest non-zero cosmological constant. An alternative to a constant vacuum density - quintessence - is mentioned.Comment: 9 pages LaTeX. Talk at COSMO-98. Asilomar, Monterey, California. November 199

Consistency Conditions for AdS/CFT Embeddings

The group embeddings used in orbifolding the AdS/CFT correspondence to arrive at quiver gauge field theories are studied for both supersymmetric and non-supersymmetric cases. For an orbifold $AdS_5 \times S^5/\Gamma$ the conditions for embeddings of the finite group $\Gamma$ in the $SU(4) \sim O(6)$ isotropy of $S^5$ are stated in the form of consistency rules, both for Abelian and Non-Abelian $\Gamma$.Comment: 10 pages LaTe

A Test of SU(15) at HERA Using The HELAS Program

A possible SU(15) process at HERA is investigated. The process that we consider is e^- P\ra \bar\nu_e \mu^- \mu^- +anything through the exchange of new heavy gauge bosons $X^-$ and $X^{--}$ which are predicted in SU(15). This process produces two easily observable like-sign muons in the final state. The cross section of this process is calculated by using HELAS and VEGAS programs, and PDF-library functions. The cross section turns out to be small to be observed in near future.Comment: 5 pages in latex with 4 figure

Quiver Gauge Theory and Unification at About 4 TeV

The use of the AdS/CFT correspondence to arrive at quiver gauge field theories is dicussed, focusing on the orbifolded case without supersymmetry. An abelian orbifold with the finite group $Z_{p}$ can give rise to a $G = SU(N)^p$ gauge group with chiral fermions and complex scalars in different bi-fundamental representations of $G$. The precision measurements at the $Z$ resonance suggest the values $p = 12$ and $N = 3$, and a unifications scale $M_U \sim 4$ TeV.The robustness and predictivity of such grand unification is discussed.Comment: 16 pages LaTeX with two eps figures. Plenary talk at SCGT02, Nagoya. Dec 200