1,957,867 research outputs found
Exact one-loop results for in 3-3-1 models
We investigate the decays , with
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
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
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
Aluminum ion-containing polyimide adhesives
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
Impact of a Science Methods Course on Pre-Service Elementary Teachers\u27 Knowledge and Confidence of Teaching with Scientific Inquiry and Problem-Based Learning
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
Red variables in the OGLE-II database. I. Pulsations and period-luminosity relations below the tip of the Red Giant Branch of the LMC
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
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
YCaBaCuO_{7-\d} (YBCO) by Hetel et al. [Nat. Phys.
3, 700 (2007)] we can extract the value of the vortex-core energy , and
show that scales linearly with at low doping.Comment: 4pages, 3 figures. References added, final versio
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