60,414 research outputs found
Z -> b\bar{b} Versus Dynamical Electroweak Symmetry Breaking involving the Top Quark
In models of dynamical electroweak symmetry breaking which sensitively
involve the third generation, such as top quark condensation, the effects of
the new dynamics can show up experimentally in Z->b\bar{b}. We compare the
sensitivity of Z->b\bar{b} and top quark production at the Tevatron to models
of the new physics. Z->b\bar{b} is a relatively more sensitive probe to new
strongly coupled U(1) gauge bosons, while it is generally less sensitive a
probe to new physics involving color octet gauge bosons as is top quark
production itself. Nonetheless, to accomodate a significant excess in
Z->b\bar{b} requires choosing model parameters that may be ruled out within run
I(b) at the Tevatron.Comment: LaTex file, 19 pages + 2 Figs., Fermilab-Pub-94/231-
Fire and rescue service community safety initiatives: measuring impact
Purpose - The purpose of this paper is to discuss methods of capturing the impact of fire and rescue service (FRS) community safety work which directly aims to reduce the occurrence of specific incidents. Design/methodology/approach - The impact assessment method described focuses on addressing one of the major problems with regards to attributing outcomes to FRS community safety work; the influence of external factors. This paper looked to assess the incident trends within a case study UK FRS within the context of the following external data sets: first, incident trends within other UK FRSs; second, demographic trends; and third, incident data from other public services. Findings - There were instances, either across the whole region served by the case study FRS, or within specific districts, where evidence suggested a strong likelihood of the community safety work of the case study FRS contributing towards an observed reduction in incidents. These findings were established through filtering the impact of widespread external factors, which could impact upon incident figures. Research limitations/implications - The utility of this impact assessment relies upon FRS consistently recording the specific aims and focus of individual community safety activity, so that any positive outcomes can be attributed to a particular group of community safety initiatives. Originality/value - This paper discusses how an evaluation process, to deter mine the likelihood of community safety impacting upon incident numbers, can be practically applied to a FRS
Exact Equivalence of the D=4 Gauged Wess-Zumino-Witten Term and the D=5 Yang-Mills Chern-Simons Term
We derive the full Wess-Zumino-Witten term of a gauged chiral lagrangian in
D=4 by starting from a pure Yang-Mills theory of gauged quark flavor in a flat,
compactified D=5. The theory is compactified such that there exists a B_5 zero
mode, and supplemented with quarks that are ``chirally delocalized'' with q_L
(q_R) on the left (right) boundary (brane). The theory then necessarily
contains a Chern-Simons term (anomaly flux) to cancel the fermionic anomalies
on the boundaries. The constituent quark mass represents chiral symmetry
breaking and is a bilocal operator in D=5 of the form: \bar{q}_LWq_R+h.c, where
W is the Wilson line spanning the bulk, 0\leq x^5 \leq R and is interpreted as
a chiral meson field, W=\exp(2i\tilde{\pi}/f_\pi), where f_\pi \sim 1/R. The
quarks are integrated out, yielding a Dirac determinant which takes the form of
a ``boundary term'' (anomaly flux return), and is equivalent to Bardeen's
counterterm that connects consistent and covariant anomalies. The
Wess-Zumino-Witten term then emerges straightforwardly, from the Yang-Mills
Chern-Simons term, plus boundary term. The method is systematic and allows
generalization of the Wess-Zumino-Witten term to theories of extra dimensions,
and to express it in alternative and more compact forms. We give a novel form
appropriate to the case of (unintegrated) massless fermions.Comment: 25 pages, 1 figure; minor errors fixe
An economic model of the manufacturers' aircraft production and airline earnings potential, volume 3
A behavioral explanation of the process of technological change in the U. S. aircraft manufacturing and airline industries is presented. The model indicates the principal factors which influence the aircraft (airframe) manufacturers in researching, developing, constructing and promoting new aircraft technology; and the financial requirements which determine the delivery of new aircraft to the domestic trunk airlines. Following specification and calibration of the model, the types and numbers of new aircraft were estimated historically for each airline's fleet. Examples of possible applications of the model to forecasting an individual airline's future fleet also are provided. The functional form of the model is a composite which was derived from several preceding econometric models developed on the foundations of the economics of innovation, acquisition, and technological change and represents an important contribution to the improved understanding of the economic and financial requirements for aircraft selection and production. The model's primary application will be to forecast the future types and numbers of new aircraft required for each domestic airline's fleet
Adaptive control of CO bending vibration: deciphering field-system dynamics
We combined adaptive closed-loop optimization, phase-shaping with a
restricted search space and imaging to control dynamics and decipher the
optimal pulse. The approach was applied to controlling the amplitude of CO
bending vibration during strong-field Coulomb explosion. The search space was
constrained by expressing the spectral phase as a Taylor series, which
generated pulses with characteristics commensurate with the natural physical
features of this problem. Optimal pulses were obtained that enhanced bending by
up to 56% relative to what is observed with comparably intense, transform
limited pulses. We show that (1) this judicious choice of a reduced parameter
set made unwrapping the dynamics more transparent and (2) the enhancement is
consistent with field-induced structural changes to a bent excited state of
CO, which theoretical simulations have identified as the state from
which the explosion originates.Comment: 4 pages, 3 figures, 1 table, added reference
Nickel layers on indium arsenide
We report here on the preparation and characterization of InAs substrates for in situ deposition of ferromagnetic contacts, a necessary precursor for semiconductor devices based on spin injection. InAs has been grown on InAs(111)A and (100) substrates by molecular-beam epitaxy and then metalized in situ in order to better understand the mechanisms that inhibit spin injection into a semiconductor. Initial x-ray characterization of the samples indicate the presence of nickel arsenides and indiumânickel compounds forming during deposition at temperatures above room temperature. Several temperature ranges have been investigated in order to determine the effect on nickel-arsenide formation. The presence of such compounds at the interface could greatly reduce the spin-injection efficiency and help elucidate previous unsuccessful attempts at measuring spin injection into InAs
Absolute Efficiency Measurements of NE-213 ORGANIC Phosphors for Detecting 14.4 and 2.6 Mev Neutrons
Efficiency measurements of organic phosphor scintillator for detecting 14.4 and 2.6 MeV neutron
Chiral Hierarchies, Compositeness and the Renormalization Group
A wide class of models involve the fine--tuning of significant hierarchies
between a strong--coupling ``compositeness'' scale, and a low energy dynamical
symmetry breaking scale. We examine the issue of whether such hierarchies are
generally endangered by Coleman--Weinberg instabilities. A careful study using
perturbative two--loop renormalization group methods finds that consistent
large hierarchies are not generally disallowed.Comment: 22 pp + 5 figs (uuencoded and submitted separately),
SSCL-Preprint-490; FERMI-PUB-93/035-
Sclera solar diameter observations
Focus is given to possible variations in solar luminosity and accurate methods of monitoring it. Aside from direct bolometry, one methodology for this type of research makes use of measurements of the solar diameter and limb darkening function as indirect indicators of the solar luminosity. This approach was reviewed
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