20,133 research outputs found

    Electric Dipole Moments in the Generic Supersymmetric Standard Model

    Get PDF
    The generic supersymmetric standard model is a model built from a supersymmetrized standard model field spectrum the gauge symmetries only. The popular minimal supersymmetric standard model differs from the generic version in having R-parity imposed by hand. We review an efficient formulation of the model and some of the recently obtained interesting phenomenological features, focusing on one-loop contributions to fermion electric dipole moments.Comment: 1+7 pages Revtex 3 figures incoporated; talk at NANP'0

    Neutrino Oscillations from Supersymmetry without R-parity - Its Implications on the Flavor Structure of the Theory

    Get PDF
    We discuss here some flavor structure aspects of the complete theory of supersymmetry without R-parity addressed from the perspective of fitting neutrino oscillation data based on the recent Super-Kamiokande result. The single-VEV parametrization of supersymmetry without R-parity is first reviewed, illustrating some important features not generally appreciated. For the flavor structure discussions, a naive, flavor model independent, analysis is presented, from which a few interesting things can be learned.Comment: 1+10 pages latex, no figure; Invited talk at NANP 99 conference, Dubna (Jun 28 - Jul 3) --- submission for the proceeding

    Little Higgs Model Completed with a Chiral Fermionic Sector

    Full text link
    The implementation of the little Higgs mechanism to solve the hierarchy problem provides an interesting guiding principle to build particle physics models beyond the electroweak scale. Most model building works, however, pay not much attention to the fermionic sector. Through a case example, we illustrate how a complete and consistent fermionic sector of the TeV effective field theory may actually be largely dictated by the gauge structure of the model. The completed fermionic sector has specific flavor physics structure, and many phenomenological constraints on the model can thus be obtained beyond gauge, Higgs, and top physics. We take a first look on some of the quark sector constraints.Comment: 14 revtex pages with no figure, largely a re-written version of hep-ph/0307250 with elaboration on flavor sector FCNC constraints; accepted for publication in Phys.Rev.

    Stabilization of the Electroweak Scale in 3-3-1 Models

    Full text link
    One way of avoiding the destabilization of the electroweak scale through a strong coupled regime naturally occurs in models with a Landau-like pole at the TeV scale. Hence, the quadratic divergence contributions to the scalar masses are not considered as a problem anymore since a new nonperturbative dynamic emerges at the TeV scale. This scale should be an intrinsic feature of the models and there is no need to invoke any other sort of protection for the electroweak scale. In some models based on the SU(3)CSU(3)WU(1)XSU(3)_C\otimes SU(3)_W\otimes U(1)_{X} gauge symmetry, a nonperturbative dynamics arise and it stabilizes the electroweak scale.Comment: 10 pages. Version with some improvements and corrections in the tex

    Include medical ethics in the Research Excellence Framework

    Get PDF
    The Research Excellence Framework of the Higher Education Funding Council for England is taking place in 2013, its three key elements being outputs (65% of the profile), impact (20%), and “quality of the research environment” (15%). Impact will be assessed using case studies that “may include any social, economic or cultural impact or benefit beyond academia that has taken place during the assessment period.”1 Medical ethics in the UK still does not have its own cognate assessment panel—for example, bioethics or applied ethics—unlike in, for example, Australia. Several researchers in medical ethics have reported to the Institute of Medical Ethics that during the internal preliminary stage of the Research Excellence Framework several medical schools have decided to include only research that entails empirical data gathering. Thus, conceptual papers and ethical analysis will be excluded. The arbitrary exclusion of reasoned discussion of medical ethics issues as a proper subject for medical research unless it is based on empirical data gathering is conceptually mistaken. “Empirical ethics” is, of course, a legitimate component of medical ethics research, but to act as though it is the only legitimate component suggests, at best, a partial understanding of the nature of ethics in general and medical ethics in particular. It also mistakenly places medicine firmly on only one side of the science/humanities “two cultures” divide instead of in its rightful place bridging the divide. Given the emphasis by the General Medical Council on medical ethics in properly preparing “tomorrow’s doctors,” we urge medical schools to find a way of using the upcoming Research Excellence Framework to highlight the expertise residing in their ethicist colleagues. We are confident that appropriate assessment will reveal work of high quality that can be shown to have social and cultural impact and benefit beyond academia, as required by the framework

    Correlations and fluctuations of a confined electron gas

    Full text link
    The grand potential Ω\Omega and the response R=Ω/xR = - \partial \Omega /\partial x of a phase-coherent confined noninteracting electron gas depend sensitively on chemical potential μ\mu or external parameter xx. We compute their autocorrelation as a function of μ\mu, xx and temperature. The result is related to the short-time dynamics of the corresponding classical system, implying in general the absence of a universal regime. Chaotic, diffusive and integrable motions are investigated, and illustrated numerically. The autocorrelation of the persistent current of a disordered mesoscopic ring is also computed.Comment: 12 pages, 1 figure, to appear in Phys. Rev.

    Effects of quark family nonuniversality in SU(3)_c X SU(4)_L X U(1)_x models

    Full text link
    Flavour changing neutral currents arise in the SU(3)cSU(4)LU(1)XSU(3)_c\otimes SU(4)_L\otimes U(1)_X extension of the standard model because anomaly cancellation among the fermion families requires one generation of quarks to transform differently from the other two under the gauge group. In the weak basis the distinction between quark families is meaningless. However, in the mass eigenstates basis, the Cabibbo-Kobayashi-Maskawa mixing matrix motivates us to classify left-handed quarks in families. In this sense there are, in principle, three different assignments of quark weak eigenstates into mass eigenstates. In this work, by using measurements at the Z-pole, atomic parity violation data and experimental input from neutral meson mixing, we examine two different models without exotic electric charges based on the 3-4-1 symmetry, and address the effects of quark family nonuniversality on the bounds on the mixing angle between two of the neutral currents present in the models and on the mass scales MZ2M_{Z_2} and MZ3M_{Z_3} of the new neutral gauge bosons predicted by the theory. The heaviest family of quarks must transform differently in order to keep lower bounds on MZ2M_{Z_2} and MZ3M_{Z_3} as low as possible without violating experimental constraints.Comment: 27 pages, 10 tables, 2 figures. Equation (19) and typos corrected. Matches version to appear in Phys. Rev.

    New Results for Diffusion in Lorentz Lattice Gas Cellular Automata

    Full text link
    New calculations to over ten million time steps have revealed a more complex diffusive behavior than previously reported, of a point particle on a square and triangular lattice randomly occupied by mirror or rotator scatterers. For the square lattice fully occupied by mirrors where extended closed particle orbits occur, anomalous diffusion was still found. However, for a not fully occupied lattice the super diffusion, first noticed by Owczarek and Prellberg for a particular concentration, obtains for all concentrations. For the square lattice occupied by rotators and the triangular lattice occupied by mirrors or rotators, an absence of diffusion (trapping) was found for all concentrations, except on critical lines, where anomalous diffusion (extended closed orbits) occurs and hyperscaling holds for all closed orbits with {\em universal} exponents df=74{\displaystyle{d_f = \frac{7}{4}}} and τ=157{\displaystyle{\tau = \frac{15}{7}}}. Only one point on these critical lines can be related to a corresponding percolation problem. The questions arise therefore whether the other critical points can be mapped onto a new percolation-like problem, and of the dynamical significance of hyperscaling.Comment: 52 pages, including 18 figures on the last 22 pages, email: [email protected]
    corecore