1,894 research outputs found

    On the Unification of Gauge Symmetries in Theories with Dynamical Symmetry Breaking

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    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

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    We point out that if quark and lepton masses arise dynamically, then in a wide class of theories the corresponding running masses mfj(p)m_{f_j}(p) exhibit the power-law decay mfj(p)∝Λj2/p2m_{f_j}(p) \propto \Lambda_j^2/p^2 for Euclidean momenta p>>Λjp >> \Lambda_j, where fjf_j is a fermion of generation jj, and Λj\Lambda_j is the maximal scale relevant for the origin of mfjm_{f_j}. 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

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    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

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    We construct extended technicolor (ETC) models that can produce the large splitting between the masses of the tt and bb quarks without necessarily excessive contributions to the ρ\rho 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 Q=2/3Q=2/3 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 mbm_b and mτm_\tau relative to mtm_t, and msm_s and mÎŒm_\mu relative to mcm_c because the masses of the Q=−1/3Q=-1/3 quarks and charged leptons require mixing between the two ETC groups, while the masses of the Q=2/3Q=2/3 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

    Bootstrapping a Terrorist Network

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    First Approach to Coupling of Numerical Lifting-Line Theory and Linear Covariance Analysis for UAV State Uncertainty Propagation

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    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

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    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 × 105 neutrophils. In experimental staphylococcal infection, skin specimens contained 34.8 ± 3.8 units MPO per gram, equivalent to 8.55 ± 0.93 × 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

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    In usual extended technicolor (ETC) theories based on the group SU(NETC)ETC{\rm{SU}(N_{ETC}})_{ETC}, 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 SU(NETC)ETC{\rm{SU}(N_{ETC}})_{ETC}. Although this mechanism would have the potential, {\it a priori}, to allow a reduction in the value of NETCN_{ETC} 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

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    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 (L,R)(L,R) components of the quarks and charged leptons transform under the ETC group. We consider K0−Kˉ0K^{0} - \bar K^0 and other pseudoscalar meson mixings, and conclude that they are adequately suppressed if the LL and RR components of the relevant quarks are assigned to the same (fundamental or conjugate-fundamental) representation of the ETC group. Models in which the LL and RR 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 LL and RR components of the quarks, as well as the leptons. We draw lessons for future ETC model building.Comment: 25 page
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