1,943,804 research outputs found

    Exact one-loop results for li→ljγl_i \to l_j\gamma in 3-3-1 models

    Full text link
    We investigate the decays li→ljγl_i\rightarrow l_j \gamma, with li=e,μ,τl_i=e,\mu,\tau in a general class of 3-3-1 models with heavy exotic leptons with arbitrary electric charges. We present full and exact analytical results keeping external lepton masses. As a by product, we perform numerical comparisons between exact results and approximate ones where the external lepton masses are neglected. As expected, we found that branching fractions can reach the current experimental limits if mixings and mass differences of the exotic leptons are large enough. We also found unexpectedly that, depending on the parameter values, there can be huge destructive interference between the gauge and Higgs contributions when the gauge bosons connecting the Standard Model leptons to the exotic leptons are light enough. This mechanism should be taken into account when using experimental constraints on the branching fractions to exclude the parameter space of the model.Comment: 27 pages, 5 figures, 4 tables; additional explanation on input parameters; matches journal versio

    Dimensional regularization of the third post-Newtonian dynamics of point particles in harmonic coordinates

    Full text link
    Dimensional regularization is used to derive the equations of motion of two point masses in harmonic coordinates. At the third post-Newtonian (3PN) approximation, it is found that the dimensionally regularized equations of motion contain a pole part [proportional to 1/(d-3)] which diverges as the space dimension d tends to 3. It is proven that the pole part can be renormalized away by introducing suitable shifts of the two world-lines representing the point masses, and that the same shifts renormalize away the pole part of the "bulk" metric tensor g_munu(x). The ensuing, finite renormalized equations of motion are then found to belong to the general parametric equations of motion derived by an extended Hadamard regularization method, and to uniquely determine the heretofore unknown 3PN parameter lambda to be: lambda = - 1987/3080. This value is fully consistent with the recent determination of the equivalent 3PN static ambiguity parameter, omega_s = 0, by a dimensional-regularization derivation of the Hamiltonian in Arnowitt-Deser-Misner coordinates. Our work provides a new, powerful check of the consistency of the dimensional regularization method within the context of the classical gravitational interaction of point particles.Comment: 82 pages, LaTeX 2e, REVTeX 4, 8 PostScript figures, minor changes to reflect Phys. Rev. D versio

    Human/computer control of undersea teleoperators

    Get PDF
    The potential of supervisory controlled teleoperators for accomplishment of manipulation and sensory tasks in deep ocean environments is discussed. Teleoperators and supervisory control are defined, the current problems of human divers are reviewed, and some assertions are made about why supervisory control has potential use to replace and extend human diver capabilities. The relative roles of man and computer and the variables involved in man-computer interaction are next discussed. Finally, a detailed description of a supervisory controlled teleoperator system, SUPERMAN, is presented

    Impact of a Science Methods Course on Pre-Service Elementary Teachers\u27 Knowledge and Confidence of Teaching with Scientific Inquiry and Problem-Based Learning

    Get PDF
    The purpose of this study was to measure the impact of an elementary science methods course on pre-service teachers\u27 knowledge and confidence of teaching with inquiry and problem-based instructional strategies. Changes in pre-service teachers\u27 knowledge and confidence were measured before and after completing the course activities using a pilot survey entitled Science Pedagogical Content Knowledge & Confidence (PCKC) Survey. An integrated lecture/laboratory elementary science methods course engaged participants with hands-on activities designed to increase their pedagogical content knowledge: including theory, planning and implementation of inquiry, and problem-based learning. The results indicated that pre-service teachers\u27 knowledge and confidence improved as a result of enrollment in the elementary science methods course. This article validates reform movements to incorporate scientific inquiry and problem-based learning into coursework

    Aluminum ion-containing polyimide adhesives

    Get PDF
    A meta-oriented aromatic diamine is reacted with an aromatic dianhydride and an aluminum compound in the presence of a water or lower alkanol miscible ether solvent to produce an intermediate polyamic acid. The polyamic acid is then converted to the thermally stable, metal ion-filled polyimide by heating in the temperature range of 300 C to produce a flexible, high temperature adhesive

    Red variables in the OGLE-II database. I. Pulsations and period-luminosity relations below the tip of the Red Giant Branch of the LMC

    Full text link
    We present period-luminosity relations for more than 23,000 red giants in the Large Magellanic Cloud observed by the OGLE-II microlensing project. The OGLE period values were combined with the 2MASS single-epoch JHK photometric data. For the brighter stars we find agreement with previous results (four different sequences corresponding to different modes of pulsation in AGB stars). We also discovered two distinct and well-separated sequences below the tip of the Red Giant Branch. They consist of almost 10,000 short-period (15 d <P< 50 d), low-amplitude (A_I<0.04 mag) red variable stars, for which we propose that a significant fraction is likely to be on the Red Giant Branch, showing radial pulsations in the second and third overtone modes. The excitation mechanism could be either Mira-like pulsation or solar-like oscillations driven by convection.Comment: 5 pages, 4 figures; accepted for publication in MNRAS (Pink Pages); proof corrections adde

    Doping dependence of the vortex-core energy in bilayer films of cuprates

    Full text link
    The energy needed to create a vortex core is the basic ingredient to address the physics of thermal vortex fluctuations in underdoped cuprates. Here we theoretically investigate its role on the occurrence of the Beresinskii-Kosterlitz-Thouless transition in a bilayer film with inhomogeneity. From the comparison with recent measurements of the penetration depth in two-unit cell thin films of Y1−x_{1-x}Cax_{x}Ba2_{2}Cu3_{3}O_{7-\d} (YBCO) by Hetel et al. [Nat. Phys. 3, 700 (2007)] we can extract the value of the vortex-core energy μ\mu, and show that μ\mu scales linearly with TcT_c at low doping.Comment: 4pages, 3 figures. References added, final versio
    • …
    corecore