870 research outputs found

    The Cabibbo Angle in a Supersymmetric D14 Model

    Get PDF
    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

    Get PDF
    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

    Essential dimension : a functorial point of view (after A. Merkurjev)

    Get PDF

    Position Drift Compensation in Port-Hamiltonian Based Telemanipulation

    Get PDF
    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

    Full text link
    Let EE be a locally compact separable metric space and mm be a positive Radon measure on it. Given a nonnegative function kk defined on E×EE\times E 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 η\eta on L2(E;m)L^2(E;m) producing a Hunt process X0X^0 on EE whose jump behaviours are governed by kk. For an arbitrary open subset D⊂ED\subset E, we also construct a Hunt process XD,0X^{D,0} on DD in an analogous manner. When DD is relatively compact, we show that XD,0X^{D,0} is censored in the sense that it admits no killing inside DD and killed only when the path approaches to the boundary. When EE is a dd-dimensional Euclidean space and mm is the Lebesgue measure, a typical example of X0X^0 is the stable-like process that will be also identified with the solution of a martingale problem up to an η\eta-polar set of starting points. Approachability to the boundary ∂D\partial D in finite time of its censored process XD,0X^{D,0} on a bounded open subset DD will be examined in terms of the polarity of ∂D\partial D for the symmetric stable processes with indices that bound the variable exponent α(x)\alpha(x).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
    • …
    corecore