1,368 research outputs found

    Is the Theta+ a K pi N bound state?

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    Following a recent suggestion that the Θ+\Theta ^+ could be a KπNK \pi N bound state we perform an investigation under the light of the meson meson and meson baryon dynamics provided by the chiral Lagrangians and using methods currently employed to dynamically generate meson and baryon resonances by means of unitary extensions of chiral perturbation theory. We consider two body and three body forces and examine the possibility of a bound state below the three particle pion-kaon-nucleon and above the kaon-nucleon thresholds. Although we find indeed an attractive interaction in the case of isospin I=0 and spin-parity 1/2+1/2^+, the interaction is too weak to bind the system. If we arbitrarily add to the physically motivated potential the needed strength to bind the system and with such strong attraction evaluate the decay width into KNK N, this turns out to be small. A discussion on further work in this direction is done.Comment: Change of title and few sentences, size of two graphs. References adde

    Filtenna Integration Achieving Ideal Chebyshev Return Losses

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    This paper demonstrates that it is possible to find an ideal filter response (Chebyshew, Butterworth,..) considering the antenna as the last resonator of a filter under certain circumstances related with the antenna performance and the bandwidth of the filtenna device. If these circumstances are not accomplished, we can achieve excellent performance as well, by means of an iterative process the goal of which is defined by either a filter mask or a classical filter function itself. The methodology is based on the conventional coupling matrix technique for filter design and has been validated by fabricating a microstrip prototype using hairpin resonators and a rectangular patch antenna

    A multistate single-connection calibration for microwave microfluidics

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    ©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.With emerging medical, chemical, and biological applications of microwave-microfluidic devices, many researchers desire a fast and accurate calibration that can be achieved in a single connection. However, traditional on-wafer or coaxial calibrations require measurements of several different artifacts to the data prior to measuring the microwave-microfluidic device. Ideally, a single artifact would be able to present different impedance states to correct the vector network analyzer data, minimizing drift and eliminating artifact-to-artifact connection errors. Here, we developed a multistate single-connection calibration that used a coplanar waveguide loaded with a microfluidic channel. We then used measurements of the uncorrected scattering parameters of the coplanar waveguide with the channel empty, filled with deionized water, and filled with 30 w% (30 grams per liter) of saline to construct an eight-term error model and switch-term correction. After correction, the residuals between measured scattering parameters and with the literaturebased finite-element simulations were below -40 dB from 100 MHz to 110 GHz. This multistate single-connection calibration is compatible with both wafer-probed and connectorized microwave-microfluidic devices for accurate impedance spectroscopy and materials characterization without the need for multiple device measurements.Peer ReviewedPostprint (author's final draft

    Nonlinear Performance of BAW Filters Including BST Capacitors

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    This paper evaluates the nonlinear effects occurring in a bulk acoustic wave (BAW) filter which includes barium strontium titanate (BST) capacitors to cancel the electrostatic capacitance of the BAW resonators. To do that we consider the nonlinear effects on the BAW resonators by use of a nonlinear Mason model. This model accounts for the distributed nonlinearities inherent in the materials forming the resonator. The whole filter is then implemented by properly connecting the resonators in a balanced configuration. Additional BST capacitors are included in the filter topology. The nonlinear behavior of the BST capacitors is also accounted in the overall nonlinear assessment. The whole circuit is then used to evaluate its nonlinear behavior. It is found that the nonlinear contribution arising from the ferroelectric nature of the BST capacitors makes it impractical to fulfill the linearity requirements of commercial filters

    Searching for tidal tails around ω\omega Centauri using RR Lyrae Stars

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    We present a survey for RR Lyrae stars in an area of 50 deg2^2 around the globular cluster ω\omega Centauri, aimed to detect debris material from the alleged progenitor galaxy of the cluster. We detected 48 RR Lyrae stars of which only 11 have been previously reported. Ten among the eleven previously known stars were found inside the tidal radius of the cluster. The rest were located outside the tidal radius up to distances of 6\sim 6 degrees from the center of the cluster. Several of those stars are located at distances similar to that of ω\omega Centauri. We investigated the probability that those stars may have been stripped off the cluster by studying their properties (mean periods), calculating the expected halo/thick disk population of RR Lyrae stars in this part of the sky, analyzing the radial velocity of a sub-sample of the RR Lyrae stars, and finally, studying the probable orbits of this sub-sample around the Galaxy. None of these investigations support the scenario that there is significant tidal debris around ω\omega Centauri, confirming previous studies in the region. It is puzzling that tidal debris have been found elsewhere but not near the cluster itself.Comment: 11 pages, 11 figures, Accepte

    Hadronic aspects of exotic baryons

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    In this talk I look into three different topics, addressing first the possibility that the Θ+\Theta^+ is a bound state of KπNK \pi N, exploiting the results of this study to find out the contribution of two meson and one baryon components in the baryon antidecuplet and in the third place I present results on a new resonant exotic baryonic state which appears as dynamically generated by the Weinberg Tomozawa ΔK\Delta K interaction.Comment: Talk at the International Workshop PENTAQUARK0

    On the determination of Θ+\Theta^+ quantum numbers and other topics of exotic baryons

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    In this talk I look into three different topics, addressing first a method to determine the quantum numbers of the Θ+\Theta^+, then exploiting the possibility that the Θ+\Theta^+ is a bound state of KπNK \pi N and in the third place I present results on a new resonant exotic baryonic state which appears as dynamically generated by the Weinberg Tomozawa ΔK\Delta K interaction.Comment: 9 pags. Talk in the NSTAR04 Workshop, Grenoble, march 200
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