35,542 research outputs found

    Enhanced coupling design of a detuned damped structure for clic

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    The key feature of the improved coupling design in the Damped Detuned Structure (DDS) is focused on the four manifolds. Rectangular geometry slots and rectangular manifolds are used. This results in a significantly stronger coupling to the manifolds compared to the previous design. We describe the new design together with its wakefield damping properties.Comment: 3 pages, 8 figures, submitted to IPAC1

    Modeling the gravitational wave signature of neutron star black hole coalescences: PhenomNSBH

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    Accurate gravitational-wave (GW) signal models exist for black-hole binary (BBH) and neutron-star binary (BNS) systems, which are consistent with all of the published GW observations to date. Detections of a third class of compact-binary systems, neutron-star-black-hole (NSBH) binaries, have not yet been confirmed, but are eagerly awaited in the near future. For NSBH systems, GW models do not exist across the viable parameter space of signals. In this work we present the frequency-domain phenomenological model, PhenomNSBH, for GWs produced by NSBH systems with mass ratios from equal-mass up to 15, spin on the black hole up to a dimensionless spin of âˆŁÏ‡âˆŁ=0.5|\chi|=0.5, and tidal deformabilities ranging from 0 (the BBH limit) to 5000. We extend previous work on a phenomenological amplitude model for NSBH systems to produce an amplitude model that is parameterized by a single tidal deformability parameter. This amplitude model is combined with an analytic phase model describing tidal corrections. The resulting approximant is accurate enough to be used to measure the properties of NSBH systems for signal-to-noise ratios (SNRs) up to 50, and is compared to publicly-available NSBH numerical-relativity simulations and hybrid waveforms constructed from numerical-relativity simulations and tidal inspiral approximants. For most signals observed by second-generation ground-based detectors within this SNR limit, it will be difficult to use the GW signal alone to distinguish single NSBH systems from either BNSs or BBHs, and therefore to unambiguously identify an NSBH system

    Renormalization group improved action on anisotropic lattices

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    We study a block spin transformation in the SU(3) lattice gauge theory on anisotropic lattices to obtain Iwasaki's renormalization group improved action for anisotropic cases. For the class of actions with plaquette and 1×21\times2 rectangular terms, we determine the improvement parameters as functions of the anisotropy Ο=as/at\xi= a_s/a_t. We find that the program of improvement works well also on anisotropic lattices. From a study of an indicator which estimates the distance to the renormalized trajectory, we show that, for the range of the anisotropy Ο≈1\xi \approx 1--4, the coupling parameters previously determined for isotropic lattices improve the theory considerably.Comment: 15 pages, 10 figure

    Enhancing Optomechanical Coupling via the Josephson Effect

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    Cavity optomechanics is showing promise for studying quantum mechanics in large systems. However, the smallness of the radiation-pressure coupling is a serious hindrance. Here we show how the charge tuning of the Josephson inductance in a single-Cooper-pair transistor can be exploited to arrange a strong radiation-pressure-type coupling g0 between mechanical and microwave resonators. In a certain limit of parameters, such a coupling can also be seen as a qubit-mediated coupling of two resonators. We show that this scheme allows reaching extremely high g0. Contrary to the recent proposals for exploiting the nonlinearity of a large radiation-pressure coupling, the main nonlinearity in this setup originates from a cross-Kerr type of coupling between the resonators, where the cavity refractive index depends on the phonon number. The presence of this coupling will allow accessing the individual phonon numbers via the measurement of the cavity.Peer reviewe
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