6,601 research outputs found

    A Novel Stealthy Target Detection Based on Stratospheric Balloon-borne Positional Instability due to Random Wind

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    A novel detection for stealthy target model F-117A with a higher aspect vision is introduced by using Stratospheric Balloon-borne Bistatic system. The potential problem of proposed scheme is platform instability impacted on the balloon by external wind force. The flight control system is studied in detail under typical random process, which is defined by Dryden turbulence spectrum. To accurately detect the stealthy target model, a real Radar Cross Section (RCS) based on physical optics (PO) formulation is applied. The sensitivity of the proposed scheme has been improved due to increasing PO – scattering field of stealthy model with higher aspect angle comparing to the conventional ground -based system. Simulations demonstrate that the proposed scheme gives much higher location accuracy and reduces location errors

    Polarized Deep Inelastic Scattering Off the "Neutron" From Gauge/String Duality

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    We investigate deep inelastic scattering off the polarized "neutron" using gauge/string duality. The "neutron" corresponds to a supergravity mode of the neutral dilatino. Through introducing the Pauli interaction term into the action in AdS5\textrm{AdS}_{5} space, we calculate the polarized deep inelastic structure functions of the "neutron" in supergravity approximation at large t' Hooft coupling λ\lambda and finite xx with λ1/2x<1\lambda^{-1/2}\ll x<1. In comparison with the charged dilatino "proton," which has been obtained in the previous work by Gao and Xiao, we find the structure functions of the "neutron" are power suppressed at the same order as the ones of the "proton." Especially, we find the Burkhardt-Cottingham-like sum rule, which is satisfied in the work by Gao and Xiao, is broken due to the Pauli interaction term. We also illustrate how such a Pauli interaction term can arise naturally from higher dimensional fermion-graviton coupling through the usual Kaluza-Klein reduction.Comment: 21pages,5figures, published versio

    Design of Compact BPF and Planar Diplexer for UMTS using Embedded-scheme Resonator

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    A compact planar diplexer utilizing embedded-scheme resonator (ESR) is designed for universal mobile telecommunications system (UMTS). The ESR is formed by embedding interdigital resonators into an open loop resonator. Based on the proposed ESR, a narrowband bandpass filter suitable for diplexer design is proposed, fabricated and measured. The measured results demonstrate that the filter exhibits good transmission properties within band and high frequency selectivity. The rectangular area occupied by the filter has overall dimensions only 0.086λg by 0.105λg, promises good potential in wireless communication systems that require compact size and high encapsulation quality. Then, a compact planar diplexer operating at the TX-band of 1920-1980MHz and the RX-band of 2110-2170MHz, which is composed of a meander T-junction and two filters initially separately designed, is synthesized, simulated and measured. Both the simulated and measured results indicate that satisfied impedance matching and good isolation between two paths have been achieved

    Lepton flavor violating signals of the neutral top-pion in future lepton colliders

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    The presence of the top-pions πt0,±\pi_{t}^{0,\pm} in the low-energy spectrum is an inevitable feature of the topcolor scenario. Taking into account the constraints of the present experimental limit of the lepton flavor violating(LFVLFV) process μeγ\mu\to e\gamma on the free parameters of topcolor-assisted techicolor(TC2) models, we study the contributions of the neutral top-pion πt0\pi^{0}_{t} to the LFVLFV processes μ+μτμ\mu^{+}\mu^{-}\to\tau \mu (or τe\tau e), γγτμ \gamma \gamma\to\tau \mu (or τe\tau e), e+eτμe^{+} e^{-}\to\tau \mu , and eγeπt0eτμ(e)e \gamma\to e \pi_{t}^{0}\to e \tau \mu(e) via the flavor changing (FCFC) couplings πt0lilj\pi_{t}^{0}l_{i}l_{j} and discuss the possibility of searching for the LFVLFV signals via these processes in future lepton colliders.Comment: References added, some typos corrected. Version to be published in Phys. Rev.

    On the thermalization of a Luttinger liquid after a sequence of sudden interaction quenches

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    We present a comprehensive analysis of the relaxation dynamics of a Luttinger liquid subject to a sequence of sudden interaction quenches. We express the critical exponent β\beta governing the decay of the steady-state propagator as an explicit functional of the switching protocol. At long distances β\beta depends only on the initial state while at short distances it is also history dependent. Continuous protocols of arbitrary complexity can be realized with infinitely long sequences. For quenches of finite duration we prove that there exist no protocol to bring the initial non-interacting system in the ground state of the Luttinger liquid. Nevertheless memory effects are washed out at short-distances. The adiabatic theorem is then investigated with ramp-switchings of increasing duration, and several analytic results for both the propagator and the excitation energy are derived.Comment: 7 pages, 4 figure

    Compact and High Performance Dual-band Bandpass Filter Using Resonator-embedded Scheme for WLANs

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    A compact microstrip dual-band bandpass filter (DBBPF) with high selectivity and good suppression for wireless local area networks (WLANs) is proposed utilizing a novel embedded scheme resonator. Two passbands are produced by a pair of embedded half-wavelength meandered stepped-impedance resonator (MSIR) and a quadwavelength short stub loaded stepped-impedance resonator (SIR) separately. The resonator is fed by folded Tshaped capacitive source-load coupling microstrip feed line, and four transmission zeros are obtained at both sides of the bands to improve selectivity and suppression. Simultaneously, the size of the filter is extermely compact because embedding half-wavelength MSIR only changes the interior configuration of quad-wavelength SIR. To validate the design method, the designed filter is fabricated and measured. Both simulated and measured results indicate that good transmission property has been achieved

    Variational calculations on the hydrogen molecular ion

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    We present high-precision non-relativistic variational calculations of bound vibrational-rotational state energies for the H2+H_2^+ and D2+D_2^+ molecular ions in each of the lowest electronic states of Σg\Sigma_g, Σu\Sigma_u, and Πu\Pi_u symmetry. The calculations are carried out including coupling between Σ\Sigma and Π\Pi states but without using the Born-Oppenheimer or any adiabatic approximation. Convergence studies are presented which indicate that the resulting energies for low-lying levels are accurate to about 101310^{-13}. Our procedure accounts naturally for the lambda-doubling of the Πu\Pi_u state.Comment: 23 pp., RevTeX, epsf.sty, 5 figs. Enhanced data in Table II, dropped 3 figs. from previous versio

    The Equation of State and Quark Number Susceptibility in Hard-Dense-Loop Approximation

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    Based on the method proposed in [ H. S. Zong, W. M. Sun, Phys. Rev. \textbf{D 78}, 054001 (2008)], we calculate the equation of state (EOS) of QCD at zero temperature and finite quark chemical potential under the hard-dense-loop (HDL) approximation. A comparison between the EOS under HDL approximation and the cold, perturbative EOS of QCD proposed by Fraga, Pisarski and Schaffner-Bielich is made. It is found that the pressure under HDL approximation is generally smaller than the perturbative result. In addition, we also calculate the quark number susceptibility (QNS) at finite temperature and finite chemical potential under hard-thermal/dense-loop (HTL/HDL) approximation and compare our results with the corresponding ones in the previous literature.Comment: 12 pages, 3 figure
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