1,836 research outputs found
Status of a Supersymmetric Flavour Violating Solution to the Solar Neutrino Puzzle with Three Generations
We present a general study of a three neutrino flavour transition model based
on the supersymmetric interactions which violate R-parity. These interactions
induce flavour violating scattering reactions between solar matter and
neutrinos. The model does not contain any vacuum mass or mixing angle for the
first generation neutrino. Instead, the effective mixing in the first
generation is induced via the new interactions. The model provides a natural
interpretation of the atmospheric neutrino anomaly, and is consistent with
reactor experiments. We determine all R-parity violating couplings which can
contribute to the effective neutrino oscillations, and summarize the present
laboratory bounds. Independent of the specific nature of the (supersymmetric)
flavour violating model, the experimental data on the solar neutrino rates and
the recoil electron energy spectrum are inconsistent with the theoretical
predictions. The confidence level of the -analysis ranges between and . The incompatibility, is due to the new SNO
results, and excludes the present model. We conclude that a non-vanishing
vacuum mixing angle for the first generation neutrino is necessary in our
model. We expect this also to apply to the solutions based on other flavour
violating interactions having constraints of the same order of magnitude.Comment: 17 pages, Latex fil
Neutrino Wave Packets in Quantum Field Theory
We present a model of neutrino oscillations in the framework of quantum field
theory in which the propagating neutrino and the particles participating to the
production and detection processes are described by wave packets. The neutrino
state is a superposition of massive neutrino wave packets determined by the
production process, as naturally expected from causality. We show that the
energies and momenta of the massive neutrino components relevant for neutrino
oscillations are in general different from the average energies and momenta of
the propagating massive neutrino wave packets, because of the effects of the
detection process. Our results confirm the correctness of the standard
expression for the oscillation length of extremely relativistic neutrinos and
the existence of a coherence length.Comment: 25 page
Reduced order models for control of fluids using the Eigensystem Realization Algorithm
In feedback flow control, one of the challenges is to develop mathematical
models that describe the fluid physics relevant to the task at hand, while
neglecting irrelevant details of the flow in order to remain computationally
tractable. A number of techniques are presently used to develop such
reduced-order models, such as proper orthogonal decomposition (POD), and
approximate snapshot-based balanced truncation, also known as balanced POD.
Each method has its strengths and weaknesses: for instance, POD models can
behave unpredictably and perform poorly, but they can be computed directly from
experimental data; approximate balanced truncation often produces vastly
superior models to POD, but requires data from adjoint simulations, and thus
cannot be applied to experimental data.
In this paper, we show that using the Eigensystem Realization Algorithm (ERA)
\citep{JuPa-85}, one can theoretically obtain exactly the same reduced order
models as by balanced POD. Moreover, the models can be obtained directly from
experimental data, without the use of adjoint information. The algorithm can
also substantially improve computational efficiency when forming reduced-order
models from simulation data. If adjoint information is available, then balanced
POD has some advantages over ERA: for instance, it produces modes that are
useful for multiple purposes, and the method has been generalized to unstable
systems. We also present a modified ERA procedure that produces modes without
adjoint information, but for this procedure, the resulting models are not
balanced, and do not perform as well in examples. We present a detailed
comparison of the methods, and illustrate them on an example of the flow past
an inclined flat plate at a low Reynolds number.Comment: 22 pages, 7 figure
Palm kernel expellers as an alternative ingredient in growing pig diets
This study evaluated the effects of palm kernel expellers in growing diets on growth performance, nutrient digestibility, and carcass and meat quality characteristics of growing-finishing pigs. A total of 88 growing pigs were randomly assigned to two dietary treatment groups. The control diet (CON) was a typical growing or finishing diet based on corn-soybean meal, and the treatment diet (PKE) was formulated by replacing CON with 20% palm kernel expellers. The PKE-CON group was fed the PKE diet during the growing period (six weeks) and the CON diet during the finishing period (12 weeks). The CON-CON group was fed the CON diets during both growing and finishing periods. The PKE-CON group showed significantly depressed growth performance and lower nutrient digestibility than the CON-CON group during the growing period. However, after feeding the typical finisher diets during the finishing period, the PKE-CON group showed no difference in growth performance in comparison with the CON-CON group during both the finishing and overall experimental periods. In addition, carcass and meat quality characteristics were not significantly different between the PKE-CON and the CON-CON groups. The results of this study imply that palm kernel expellers can be an alternative ingredient in the growing diets of growing-finishing pigs if the combined feeding strategy (PKE for the growing period and CON for the finishing period) is used.Keywords: Feed alternatives, growing pig diet, growth performance, meat quality traits, palm kernel expelle
Chiral corrections to the axial charges of the octet baryons from quenched QCD
We calculate one-loop correction to the axial charges of the octet baryons
using quenched chiral perturbation theory, in order to understand chiral
behavior of the axial charges in quenched approximation to quantum
chromodynamics (QCD). In contrast to regular behavior of the full QCD chiral
perturbation theory result, , we find
that the quenched chiral perturbation theory result,
, is
singular in the chiral limit.Comment: standard LaTeX, 16 pages, 4 epsf figure
Survey of Sensor Technology for Aircraft Cabin Environment Sensing
The aircraft cabin environment is unique due to the proximity of the passengers, the need for cabin pressurization, and the low humidity. All of these aspects are complicated by the fact that the aircraft is a semi-enclosed structure. There is an increased desire to monitor the aircraft cabin environment with various sensors for comfort and safety. However, the aircraft cabin environment is composed of a large number of factors. Some of these factors can include air quality, temperature, level of pressurization, and motion of the aircraft. Therefore, many types of sensors must be used to monitor aircraft environments. A variety of technology options are often available for each sensor. Consequently, a fair number of tradeoffs need to be carefully considered when designing a sensor monitoring system for the aircraft cabin environment. For instance, a system designer may need to decide if the increased accuracy of a sensor using a particular technology is worth the increased power consumption over a similar sensor employing a more efficient, less accurate technology. In order to achieve a good solution, a designer needs to understand the tradeoffs and general operation for all of the different sensor technologies that could be used in the design. The purpose of this paper is to provide a survey of the current sensor technology. The primary focus of this paper is on sensors and technologies that cover the most common aspects of aircraft cabin environment monitoring. The first half of this paper details the basic operation of different sensor technologies. The second half covers the individual environmental conditions which need to be sensed. This will include the benefits, limitations, and applications of the different technologies available for each particular type of sensor
YREC: The Yale Rotating Stellar Evolution Code
The stellar evolution code YREC is outlined with emphasis on its applications
to helio- and asteroseismology. The procedure for calculating calibrated solar
and stellar models is described. Other features of the code such as a non-local
treatment of convective core overshoot, and the implementation of a
parametrized description of turbulence in stellar models, are considered in
some detail. The code has been extensively used for other astrophysical
applications, some of which are briefly mentioned at the end of the paper.Comment: 10 pages, 2 figures, ApSS accepte
The anti-B --> D* lepton anti-neutrino form factor at zero recoil and the determination of V(cb)
We summarize our lattice QCD study of the form factor at zero recoil in the
decay anti-B --> D* lepton anti-neutrino. After careful consideration of all
sources of systematic uncertainty, we find,
h_A1(1) = 0.913(+0.024-0.017)(+0.017-0.030), where the first uncertainty is
from statistics and fitting while the second combined uncertainty is from all
other systematic effects.Comment: Lattice2001(HeavyQuark); 3 pages, 2 eps figures, espcrc2.st
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