4,914 research outputs found

    Enhanced coherent dynamics near a transition between neutral quantum-paraelectric and ionic ferroelectric phases in the quantum Blume-Emery-Griffiths model

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    Nonequilibrium dynamics are studied near the quantum phase transition point in the one-dimensional quantum Blume-Emery-Griffiths model. Its pseudo-spin component Sz S^z represents an electric polarization, and (Sz)2 (S^z)^2 corresponds to ionicity, in mixed-stack charge-transfer complexes that exhibit a transition between neutral quantum-paraelectric and ionic ferroelectric (or antiferroelectric) phases. The time-dependent Schr\"odinger equation is solved for the exact many-body wave function in the quantum paraelectric phase. After impact force is introduced on a polarization locally in space and time, polarizations and ionicity coherently oscillate. The oscillation amplitudes are large near the quantum phase transition point. The energy supplied by the impact flows linearly into these oscillations, so that the nonequilibrium behavior is uncooperative.Comment: 6 pages, 4 figures, accepted for publication in Phys. Rev.

    Discussion of: Brownian distance covariance

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    Discussion on "Brownian distance covariance" by G\'{a}bor J. Sz\'{e}kely and Maria L. Rizzo [arXiv:1010.0297]Comment: Published in at http://dx.doi.org/10.1214/09-AOAS312E the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Variations on the Supersymmetric Q6 Model of Flavor

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    We observe that a recently proposed supersymmetric model with Q6 flavor symmetry admits a new CP violating ground state. A new sum rule for the quark mixing parameters emerges, which is found to be consistent with data. Simple extensions of the model to the neutrino sector suggest an inverted hierarchical mass spectrum with nearly maximal CP violation (|delta_{MNS}| simeq pi/2). Besides reducing the number of parameters in the fermion sector, these models also provide solutions to the SUSY flavor problem and the SUSY CP problem. We construct a renormalizable scalar potential that leads to the spontaneous breaking of CP symmetry and the family symmetry.Comment: 22 pages, 7 figure

    Application of the Hilbert-Huang Transform to the Search for Gravitational Waves

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    We present the application of a novel method of time-series analysis, the Hilbert-Huang Transform, to the search for gravitational waves. This algorithm is adaptive and does not impose a basis set on the data, and thus the time-frequency decomposition it provides is not limited by time-frequency uncertainty spreading. Because of its high time-frequency resolution it has important applications to both signal detection and instrumental characterization. Applications to the data analysis of the ground and space based gravitational wave detectors, LIGO and LISA, are described

    Mott Gap Excitations and Resonant Inelastic X-Ray Scattering in Doped Cuprates

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    Predictions are made for the momentum- and carrier-dependent degradation of the Mott gap upon doping in high-Tc cuprates as would be observed in Cu K-edge resonant inelastic x-ray scattering (RIXS). The two-dimensional Hubbard model with second- and third-nearest-neighbor hopping terms has been studied by numerical exact diagonalization. Special emphasis is placed on the particle-hole asymmetry of the Mott gap excitations. We argue that the Mott gap excitations observed by RIXS are significantly influenced by the interaction between charge carriers and antiferromagnetic correlations.Comment: 4 pages, 4 figures, revised version; to be published in Phys. Rev. Let

    Marketization of Care and Gendered Cross-Border Migration from Indonesia to Malaysia: The Case of Indonesian Female Migrant Domestic Workers in/to Malaysia.

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    Introduction For the last two decades, the rights of domestic workers have drawn attention from academia, policy makers, NGO workers and human rights activists. The International Labour Organization (ILO) (2011) estimates that there are currently 53 to 100 million domestic workers worldwide (around 83% of whom are women and girls), and many of them, especially the female live-in migrant domestic workers (MDWs), are working under precarious conditions without any labour rights. Since domestic work is undervalued and poorly regulated, domestic workers remain overworked, underpaid and unprotected. Media reports have increasingly highlighted the plight of MDWs in the different parts of world who suffer from maltreatment, such as control of mobility through withholding identity papers, physical abuse, sexual harassment, overtime work and wage denial. Yet, public authorities have been reluctant to intervene in the defense of domestic workers, primarily because domestic work is regarded as a “private” issue within the family. Government intervention mainly takes the form of banning the migration of women in low-skilled sectors altogether or domestic workers specifically, rather than finding measures to protect the rights of these migrant

    Spatially Inhomogeneous Superconducting State near Hc2H_{\rm c2} in UPd2_2Al3_3

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    We have performed 27^{27}Al-NMR measurements on single-crystalline UPd2_2Al3_3 with the field parallel to the cc axis to investigate the superconducting (SC) properties near the upper critical field of superconductivity Hc2H_{\rm c2}. The broadening of the NMR linewidth below 14~K indicates the appearance of the internal field at the Al site, which originates from the antiferromagnetically ordered moments of U 5ff electrons. In the SC state well below μ0Hc2\mu_0H_{\rm c2} = 3.4~T, the broadening of the NMR linewidth due to the SC diamagnetism and a decrease in the Knight shift are observed, which are well-understood by the framework of spin-singlet superconductivity. In contrast, the Knight shift does not change below Tc(H)T_{\rm c}(H), and the NMR spectrum is broadened symmetrically in the SC state in the field range of 3~T <μ0H<μ0Hc2< \mu_0 H < \mu_0 H_{\rm c2}. The unusual NMR spectrum near Hc2H_{\rm c2} suggests that a spatially inhomogeneous SC state such as the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state would be realized.Comment: 5 pages, 5 figure

    Charge ordering in \theta-(BEDT-TTF)2RbZn(SCN)4: Cooperative effects of electron correlations and lattice distortions

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    Combined effects of electron correlations and lattice distortions are investigated on the charge ordering in \theta-(BEDT-TTF)2RbZn(SCN)4 theoretically in a two-dimensional 3/4-filled extended Hubbard model with electron-lattice couplings. It is known that this material undergoes a phase transition from a high-symmetry metallic state to a low-symmetry insulating state with a horizontal-stripe charge order (CO) by lowering temperature. By means of the exact-diagonalization method, we show that electron-phonon interactions are crucial to stabilize the horizontal-stripe CO and to realize the low-symmetry crystal structure.Comment: 7 peges, 7 figures, accepted for publication in Phys. Rev.
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