Supersymmetric model of quasi-degenerate neutrinos

We present a supersymmetric model of fermion masses, based on a non-Abelian family symmetry and the Froggatt-Nielsen mechanism, that can account for the solar and atmospheric neutrino problems via quasi-degenerate neutrinos. The model predicts that the ratio of neutrino mass squared splittings \Delta m^2_{12} / \Delta m^2_{23} is of order m_s^2/m_b^2, and the angles \theta_{12} \sim m_d/m_s and \theta_{23} \sim 1, which are of the desired orders of magnitude. We discuss the implications of the flavor structure of the neutrino sector on superparticle masses and mixing angles.Comment: 14 pages LaTeX, two EPS figure

SET based experiments for HTSC materials: II

The cuprates seem to exhibit statistics, dimensionality and phase transitions in novel ways. The nature of excitations [i.e. quasiparticle or collective], spin-charge separation, stripes [static and dynamics], inhomogeneities, psuedogap, effect of impurity dopings [e.g. Zn, Ni] and any other phenomenon in these materials must be consistently understood. In this note we further discuss our original suggestion of using Single Electron Tunneling Transistor [SET] based experiments to understand the role of charge dynamics in these systems. Assuming that SET operates as an efficient charge detection system we can expect to understand the underlying physics of charge transport and charge fluctuations in these materials for a range of doping. Experiments such as these can be classed in a general sense as mesoscopic and nano characterization of cuprates and related materials. In principle such experiments can show if electron is fractionalized in cuprates as indicated by ARPES data. In contrast to flux trapping experiments SET based experiments are more direct in providing evidence about spin-charge separation. In addition a detailed picture of nano charge dynamics in cuprates may be obtained.Comment: 10 pages revtex plus four figures; ICMAT 2001 Conference Symposium P: P10-0

New Bounds on Isotropic Lorentz Violation

Violations of Lorentz invariance that appear via operators of dimension four or less are completely parameterized in the Standard Model Extension (SME). In the pure photonic sector of the SME, there are nineteen dimensionless, Lorentz-violating parameters. Eighteen of these have experimental upper bounds ranging between 10^{-11} and 10^{-32}; the remaining parameter, k_tr, is isotropic and has a much weaker bound of order 10^{-4}. In this Brief Report, we point out that k_tr gives a significant contribution to the anomalous magnetic moment of the electron and find a new upper bound of order 10^{-8}. With reasonable assumptions, we further show that this bound may be improved to 10^{-14} by considering the renormalization of other Lorentz-violating parameters that are more tightly constrained. Using similar renormalization arguments, we also estimate bounds on Lorentz violating parameters in the pure gluonic sector of QCD.Comment: 10 pages, 1 figure. v2: reference adde

Kaluza-Klein Mesons in Universal Extra Dimensions

In models with universal extra dimensions, the isosinglet Kaluza-Klein (KK) quarks, q^1, have very narrow widths, of O(5-10) MeV, and will thus hadronize. Studies of KK-quarkonia, \bar{q}^1 q^1, show very sharp resonances and dramatic signatures at the Linear Collider. In this Brief Report, we consider the possibility of detecting KK-mesons, \bar{q}^1 q, and show that detection at a Linear Collider is unlikely.Comment: One paragraph regarding KK-meson annihilation added. Version to appear in Physical Review

Interactive estimating for building contractors

The objective of this work was to develop a computer-aided estimating system to meet the specific requirements of the British building industry. The sponsor was the National Research Development Corporation. The project comprised: -a review of existing commercially available computer-aided estimating systems suitable for use by building contractors to establish the need for the project; -a review of computer applications in the construction industry to establish the context in which computer-aided estimating systems could be applied; -the development of a computer-aided estimating system specification for a system, INTEREST BUILD (INTERactive ESTimating for BUILDers), suitable for programming work by computer programmers; -an appraisal and review of available classification systems for use with the estimating system; -the development of a classification specifically for use with the INTEREST BUILD system against which performance data could be filed and retrieved; -the collection of estimators' performance data suitable for use in demonstrating and testing the system; and -the demonstrations, testing .and assessments of the INTEREST BUILD.system. <~,. Five commercially available estimating systems were investigated and none were found to fully meet the needs of building estimators. A review of computer applications for contractors revealed that existing applications in order of popularity were: accounting; network analysis; costing; cash flow forecasting; estimating; NEDO formulae; valuations; and discounted cash flow. [continues

The Anomalous Magnetic Moment of the Muon and Higgs-Mediated Flavor Changing Neutral Currents

In the two-Higgs doublet extension of the standard model, flavor-changing neutral couplings arise naturally. In the lepton sector, the largest such coupling is expected to be $\mu-\tau-\phi#. We consider the effects of this coupling on the anomalous magnetic moment of the muon. The resulting bound on the coupling, unlike previous bounds, is independent of the value of other unknown couplings. It will be significantly improved by the upcoming E821 experiment at Brookhaven National Lab.Comment: 7 pages Latex, 2 figure

Holographic Electroweak Symmetry Breaking from D-branes

We observe several interesting phenomena in a technicolor-like model of electroweak symmetry breaking based on the D4-D8-D8bar system of Sakai and Sugimoto. The benefit of holographic models based on D-brane configurations is that both sides of the holographic duality are well understood. We find that the lightest technicolor resonances contribute negatively to the Peskin-Takeuchi S-parameter, but heavy resonances do not decouple and lead generically to large, positive values of S, consistent with standard estimates in QCD-like theories. We study how the S parameter and the masses and decay constants of the vector and axial-vector techni-resonances vary over a one-parameter family of D8-brane configurations. We discuss possibilities for the consistent truncation of the theory to the first few resonances and suggest some generic predictions of stringy holographic technicolor models.Comment: REVTeX, 25 pages, 8 eps figures, version published in PR