870 research outputs found
The Cabibbo Angle in a Supersymmetric D14 Model
We construct a supersymmetric model with the flavor symmetry D14 in which the
CKM matrix element |V_{ud}| can take the value |V_{ud}| =cos (pi/14) = 0.97493
implying that the Cabibbo angle theta_C is sin (theta_C) = |V_{us}| = sin
(pi/14) = 0.2225. These values are very close to those observed in experiments.
The value of |V_{ud}| (theta_C) is based on the fact that different Z2
subgroups of D14 are conserved in the up and down quark sector. In order to
achieve this, D14 is accompanied by a Z3 symmetry. The spontaneous breaking of
D14 is induced by flavons, which are scalar gauge singlets. The quark mass
hierarchy is partly due to the flavor group D14 and partly due to a
Froggatt-Nielsen symmetry U(1)_{FN} under which only the right-handed quarks
transform. The model is completely natural in the sense that the hierarchies
among the quark masses and mixing angles are generated with the help of
symmetries. The issue of the vacuum alignment of the flavons is solved up to a
small number of degeneracies, leaving four different possible values for
|V_{ud}|. Out of these, only one of them leads to a phenomenological viable
model. A study of the Z2 subgroup breaking terms shows that the results
achieved in the symmetry limit are only slightly perturbed. At the same time
they allow |V_{ud}| (theta_C) to be well inside the small experimental error
bars.Comment: 1+24 page
An Extended Virtual Aperture Imaging Model for Through-the-wall Sensing and Its Environmental Parameters Estimation
Through-the-wall imaging (TWI) radar has been given increasing attention in recent years. However, prior knowledge about environmental parameters, such as wall thickness and dielectric constant, and the standoff distance between an array and a wall, is generally unavailable in real applications. Thus, targets behind the wall suffer from defocusing and displacement under the conventional imagÂŹing operations. To solve this problem, in this paper, we first set up an extended imaging model of a virtual aperture obtained by a multiple-input-multiple-output array, which considers the array position to the wall and thus is more applicable for real situations. Then, we present a method to estimate the environmental parameters to calibrate the TWI, without multiple measurements or dominant scatterÂŹers behind-the-wall to assist. Simulation and field experiÂŹments were performed to illustrate the validity of the proÂŹposed imaging model and the environmental parameters estimation method
Position Drift Compensation in Port-Hamiltonian Based Telemanipulation
Passivity based bilateral telemanipulation schemes are often subject to a position drift between master and slave if the communication channel is implemented using scattering variables. The magnitude of this position mismatch can be significant during interaction tasks. In this paper we propose a passivity preserving scheme for compensating the position drift arising during contact tasks in port-Hamiltonian based telemanipulation improving the kinematic perception of the remote environment felt by the human operato
Jump-type Hunt processes generated by lower bounded semi-Dirichlet forms
Let be a locally compact separable metric space and be a positive
Radon measure on it. Given a nonnegative function defined on
off the diagonal whose anti-symmetric part is assumed to be less singular than
the symmetric part, we construct an associated regular lower bounded
semi-Dirichlet form on producing a Hunt process on
whose jump behaviours are governed by . For an arbitrary open subset
, we also construct a Hunt process on in an analogous
manner. When is relatively compact, we show that is censored in
the sense that it admits no killing inside and killed only when the path
approaches to the boundary. When is a -dimensional Euclidean space and
is the Lebesgue measure, a typical example of is the stable-like
process that will be also identified with the solution of a martingale problem
up to an -polar set of starting points. Approachability to the boundary
in finite time of its censored process on a bounded open
subset will be examined in terms of the polarity of for the
symmetric stable processes with indices that bound the variable exponent
.Comment: Published in at http://dx.doi.org/10.1214/10-AOP633 the Annals of
Probability (http://www.imstat.org/aop/) by the Institute of Mathematical
Statistics (http://www.imstat.org
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