49,329 research outputs found

    Gravitomagnetic Field and Time-Dependent Spin-Rotation Coupling

    Get PDF
    The Kerr metric of spherically symmetric gravitational field is analyzed through the coordinate transformation from the rotating frame to fixing frame, and consequently that the inertial force field (with the exception of the centrifugal force field) in the rotating system is one part of its gravitomagnetic field is verified. We investigate the spin-rotation coupling and, by making use of Lewis-Riesenfeld invariant theory, we obtain exact solutions of the Schr\"{o}dinger equation of a spinning particle in a time-dependent rotating reference frame. A potential application of these exact solutions to the investigation of Earth,^{,}s rotating frequency fluctuation by means of neutron-gravity interferometry experiment is briefly discussed in the present paper.Comment: 6 pages, 0 figures, Late

    Anomalous Higgs-top Coupling Pollution on Triple Higgs Coupling Extraction at Future High-Luminosity Electron-Positron Collider

    Full text link
    One of the most challenging tasks for future high-luminosity electron-positron colliders is to extract Higgs triple coupling. It was proposed that this can be carried out via the precisely measuring the cross section of ZH associated production up to 0.4%0.4\%. In this paper, we example the possible heavy pollution from Higgs-top anomalous coupling. Our numerical results show that the pollution is small for se+e−=240GeV\sqrt{s}_{e^+e^-}= 240 GeV. However for the higher energy collider, pollution is sizable, which should be taken into account. We further explored the possibility to measure CP-violated Higgs top coupling, via the forward-backward asymmetry AFBA_{FB} for the process e+e−→ZHe^+e^- \rightarrow ZH. The asymmetry can reach 0.7%0.7\% which is comparable to the precision of cross section measurement.Comment: 10 pages, 6 figures, discussions and references added, published in Phys. Rev.

    Parton recombination effect in polarized parton distributions

    Full text link
    Parton recombination corrections to the standard spin-dependent Altarelli-Parisi evolution equation are considered in a nonlinear evolution equation. The properties of this recombination equation and its relation with the spin-averaged form are discussed.Comment: 25 pages, 1 figure, to be published in Nucl. Phys. B. Appendix is correcte

    Reimagining career guidance: towards a pluralistic perspective

    Get PDF
    Difficulties concerning the identified mis-match between supply and demand sides of the labour market are discussed. The variability of career guidance services for young people across Europe is illustrated together with policy initiatives in some cases leading to problems of professional identity and limited support to clients of the service. The risks associated with a monoculture of ‘one size fits all’ approach to guidance practice are discussed. The principles of pluralistic approaches to counselling are discussed with the suggestion that this might prove to be a fertile way forward for career guidance practice

    Improved speed estimation in sensorless PM brushless AC drives

    Get PDF
    The application of flux-observer-based sensorless control to permanent-magnet brushless AC motor drives is described. Current methods of speed estimation are assessed, both theoretically and experimentally, and an improved method, which combines the best features of methods in which speed is derived from the differential of rotor position and from the ratio of the electromotive force to excitation flux linkage, is proposed. Its performance is verified experimentally

    The chaotic effects in a nonlinear QCD evolution equation

    Get PDF
    The corrections of gluon fusion to the DGLAP and BFKL equations are discussed in a united partonic framework. The resulting nonlinear evolution equations are the well-known GLR-MQ-ZRS equation and a new evolution equation. Using the available saturation models as input, we find that the new evolution equation has the chaos solution with positive Lyaponov exponents in the perturbative range. We predict a new kind of shadowing caused by chaos, which blocks the QCD evolution in a critical small xx range. The blocking effect in the evolution equation may explain the Abelian gluon assumption and even influence our expectations to the projected Large Hadron Electron Collider (LHeC), Very Large Hadron Collider (VLHC) and the upgrade (CppC) in a circular e+e−e^+e^- collider (SppC).Comment: 58 pages, 23 figures,. Final version to appear in NP

    Exact solutions to the time-dependent supersymmetric muliphoton Jaynes-Cummings model and the Chiao-Wu model

    Full text link
    By using both the Lewis-Riesenfeld invariant theory and the invariant-related unitary transformation formulation, the present paper obtains the exact solutions to the time-dependent supersymmetric two-level multiphoton Jaynes-Cummings model and the Chiao-Wu model that describes the propagation of a photon inside the optical fiber. On the basis of the fact that the two-level multiphoton Jaynes-Cummings model possesses the supersymmetric structure, an invariant is constructed in terms of the supersymmetric generators by working in the sub-Hilbert-space corresponding to a particular eigenvalue of the conserved supersymmetric generators (i.e., the time-independent invariant). By constructing the effective Hamiltonian that describes the interaction of the photon with the medium of the optical fiber, it is further verified that the particular solution to the Schr\"{o}dinger equation is the eigenfunction of the second-quantized momentum operator of photons field. This, therefore, means that the explicit expression (rather than the hidden form that involves the chronological product) for the time-evolution operator of wave function is obtained by means of the invariant theories.Comment: 14 pages, Latex. This is a revised version of the published paper: Shen J Q, Zhu H Y 2003 Ann. Phys.(Leipzig) Vol.12 p.131-14
    • …
    corecore