1,894 research outputs found
On the Unification of Gauge Symmetries in Theories with Dynamical Symmetry Breaking
We analyze approaches to the partial or complete unification of gauge
symmetries in theories with dynamical symmetry breaking. Several types of
models are considered, including those that (i) involve sufficient unification
to quantize electric charge, (ii) attempt to unify the three standard-model
gauge interactions in a simple Lie group that forms a direct product with an
extended technicolor group, and, most ambitiously, (iii) attempt to unify the
standard-model gauge interactions with (extended) technicolor in a simple Lie
group.Comment: 24 pages, ReVTe
Implications of Dynamical Generation of Standard-Model Fermion Masses
We point out that if quark and lepton masses arise dynamically, then in a
wide class of theories the corresponding running masses exhibit
the power-law decay for Euclidean momenta
, where is a fermion of generation , and
is the maximal scale relevant for the origin of . We estimate
resultant changes in precision electroweak quantities and compare with current
data. It is found that this data allows the presence of such corrections. We
also note that this power-law decay renders primitively divergent fermion mass
corrections finite.Comment: 4 pages, late
POPULAR INFORMATIONAL PRIORITIES IN AGRICULTURAL EXTENSION
Due to agriculture's increasingly complex technical and economic environment, the diversity of information required for competitive and profitable farming is growing as never before. With constant and, in some cases, reduced resources for agricultural programs, Extension must exercise special care in prioritizing informational efforts to best meet farm-client needs and retain an important base of public support. This paper presents a method of identifying popular informational priorities in Agricultural Extension. The method is illustrated by application to dairy programming in Massachusetts.Teaching/Communication/Extension/Profession,
Extended Technicolor Models with Two ETC Groups
We construct extended technicolor (ETC) models that can produce the large
splitting between the masses of the and quarks without necessarily
excessive contributions to the parameter or to neutral flavor-changing
processes. These models make use of two different ETC gauge groups, such that
left- and right-handed components of charge quarks transform under the
same ETC group, while left- and right-handed components of charge -1/3 quarks
and charged leptons transform under different ETC groups. The models thereby
suppress the masses and relative to , and and
relative to because the masses of the quarks and charged leptons
require mixing between the two ETC groups, while the masses of the
quarks do not. A related source of the differences between these mass
splittings is the effect of the two hierarchies of breaking scales of the two
ETC groups. We analyze a particular model of this type in some detail. Although
we find that this model tends to suppress the masses of the first two
generations of down-type quarks and charged leptons too much, it gives useful
insights into the properties of theories with more than one ETC group.Comment: 14 pages, 4 figure
First Approach to Coupling of Numerical Lifting-Line Theory and Linear Covariance Analysis for UAV State Uncertainty Propagation
Numerical lifting-line is a computationally efficient method for calculating aerodynamic forces and moments on aircraft. However, its potential has yet to be tapped for use in guidance, navigation, and control (GN&C). Linear covariance analysis is becoming a popular GN&C design tool and shows promise for pairing with numerical lifting-line. Pairing numerical lifting-line with linear covariance analysis allows for forward propagation of state uncertainty for real-time decision making. We demonstrate this for select state variables in a drone aerial recapture situation. Linear covariance analysis uses finite difference derivatives obtained from numerical lifting-line to calculate force and moment variances. These show agreement with Monte Carlo simulation results to within 10%, without the significant computational cost of Monte Carlo. These results show numerical lifting-line can be used in linear covariance analysis of an entire UAV GN&C solution. Not only does this allow for real-time uncertainty propagation, but also faster and more thorough multi-disciplinary design optimization
Measurement of Cutaneous Inflammation: Estimation of Neutrophil Content with an Enzyme Marker
We examined the hypothesis that myeloperoxidase (MPO), a plentiful constituent of neutrophils, might seve as a marker for tissue neutrophil content. To completely extract MPO from either neutrophils or skin, hexadecyl-trimethylammonium bromide (HTAB) was used to solubilize the enzyme. With this detergent treatment, 97.8 ± 0.2% of total recoverable MPO was extracted from neutrophils with a single HTAB treatment; 93.1 ± 1.0% was solubilized with a single treatment of skin. Neutrophil MPO was directly related to neutrophil number; with the dianisidine-H2O2 assay as few as 104 neutrophils could be detected. The background level of MPO within uninflamed tissue was 0.385 ± 0.018 units per gram of tissue, equivalent to only 7.64 ± 0.36 à 105 neutrophils. In experimental staphylococcal infection, skin specimens contained 34.8 ± 3.8 units MPO per gram, equivalent to 8.55 ± 0.93 à 107 neutrophils. These studies demonstrate that MPO can be used as a marker for skin neutrophil content: it is recoverable from skin in soluble form, and is directly related to neutrophil number. Further, normal skin possesses a low background of MPO compared to that of inflamed skin
Study of an Alternate Mechanism for the Origin of Fermion Generations
In usual extended technicolor (ETC) theories based on the group
, the quarks of charge 2/3 and -1/3 and the charged
leptons of all generations arise from ETC fermion multiplets transforming
according to the fundamental representation. Here we investigate a different
idea for the origin of SM fermion generations, in which quarks and charged
leptons of different generations arise from ETC fermions transforming according
to different representations of . Although this
mechanism would have the potential, {\it a priori}, to allow a reduction in the
value of relative to conventional ETC models, we show that, at least
in simple models, it is excluded by the fact that the technicolor sector is not
asymptotically free or by the appearance of fermions with exotic quantum
numbers which are not observed.Comment: 6 pages, late
Flavor-Changing Processes in Extended Technicolor
We analyze constraints on a class of extended technicolor (ETC) models from
neutral flavor-changing processes induced by (dimension-six) four-fermion
operators. The ETC gauge group is taken to commute with the standard-model
gauge group. The models in the class are distinguished by how the left- and
right-handed components of the quarks and charged leptons transform
under the ETC group. We consider and other pseudoscalar
meson mixings, and conclude that they are adequately suppressed if the and
components of the relevant quarks are assigned to the same (fundamental or
conjugate-fundamental) representation of the ETC group. Models in which the
and components of the down-type quarks are assigned to relatively conjugate
representations, while they can lead to realistic CKM mixing and intra-family
mass splittings, do not adequately suppress these mixing processes. We identify
an approximate global symmetry that elucidates these behavioral differences and
can be used to analyze other possible representation assignments.
Flavor-changing decays, involving quarks and/or leptons, are adequately
suppressed for any ETC-representation assignment of the and components
of the quarks, as well as the leptons. We draw lessons for future ETC model
building.Comment: 25 page
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