17,703 research outputs found

    Transverse Ward-Takahashi Identity, Anomaly and Schwinger-Dyson Equation

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    Based on the path integral formalism, we rederive and extend the transverse Ward-Takahashi identities (which were first derived by Yasushi Takahashi) for the vector and the axial vector currents and simultaneously discuss the possible anomaly for them. Subsequently, we propose a new scheme for writing down and solving the Schwinger-Dyson equation in which the the transverse Ward-Takahashi identity together with the usual (longitudinal) Ward-Takahashi identity are applied to specify the fermion-boson vertex function. Especially, in two dimensional Abelian gauge theory, we show that this scheme leads to the exact and closed Schwinger-Dyson equation for the fermion propagator in the chiral limit (when the bare fermion mass is zero) and that the Schwinger-Dyson equation can be exactly solved.Comment: 22 pages, latex, no figure

    Prediction of the capacitance lineshape in two-channel quantum dots

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    We propose a set-up to realize two-channel Kondo physics using quantum dots. We discuss how the charge fluctuations on a small dot can be accessed by using a system of two single electron transistors arranged in parallel. We derive a microscopic Hamiltonian description of the set-up that allows us to make connection with the two-channel Anderson model (of extended use in the context of heavy-Fermion systems) and in turn make detailed predictions for the differential capacitance of the dot. We find that its lineshape, which we determined precisely, shows a robust behavior that should be experimentally verifiable.Comment: 4 pages, 3 figure

    Theory of spin-polarized transport in semiconductor heterojunctions: Proposal for spin injection and detection in silicon

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    Spin injection and detection in silicon is a difficult problem, in part because the weak spin-orbit coupling and indirect gap preclude using standard optical techniques. We propose two ways to overcome this difficulty, and illustrate their operation by developing a model for spin-polarized transport across a heterojunction. We find that equilibrium spin polarization of holes leads to a strong modification of the spin and charge dynamics of electrons, and we show how the symmetry properties of the charge current can be exploited to detect spin injection in silicon using currently available techniques.Comment: 4 pages, 4 figures, added footnot

    Renormalizing a BRST-invariant composite operator of mass dimension 2 in Yang-Mills theory

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    We discuss the renormalization of a BRST and anti-BRST invariant composite operator of mass dimension 2 in Yang-Mills theory with the general BRST and anti-BRST invariant gauge fixing term of the Lorentz type. The interest of this study stems from a recent claim that the non-vanishing vacuum condensate of the composite operator in question can be an origin of mass gap and quark confinement in any manifestly covariant gauge, as proposed by one of the authors. First, we obtain the renormalization group flow of the Yang-Mills theory. Next, we show the multiplicative renormalizability of the composite operator and that the BRST and anti-BRST invariance of the bare composite operator is preserved under the renormalization. Third, we perform the operator product expansion of the gluon and ghost propagators and obtain the Wilson coefficient corresponding to the vacuum condensate of mass dimension 2. Finally, we discuss the connection of this work with the previous works and argue the physical implications of the obtained results.Comment: 49 pages, 35 eps-files, A number of typographic errors are corrected. A paragraph is added in the beginning of section 5.3. Two equations (7.1) and (7.2) are added. A version to be published in Phys. Rev.

    Tanggung Jawab Hukum Dalam Perjanjian Sewa Menyewa Rumah Toko (Ruko)

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    Tujuan dilakukan penelitian ini adalah untuk mengetahui bagaimanakah prosedur pembuatan perjanjian sewa menyewa Ruko dan bagaimanakah tanggung jawab hukum para pihak dalam pelaksanaan perjanjian sewa menyewa Ruko. Dalam melaklukan penelitian penyusunan Skripsi digunakan metode penelitian hokum normative dan dapat disimpulkan: 1. Perjanjian akan dapat terlaksana apabila prosedur atau tahapan-tahapan dapat dipahami dengan benar oleh para pihak, baik pihak yang menyewakan ruko dan pihak penyewa ruko. 2. Tanggung jawab hukum para pihak dalam pelaksanaan perjanjian sewa menyewa ruko dapat dilihat pada hak dan kewajiban para pihak, baik pihak yang menyewakan ruko maupun pihak penyewa ruko. Apabila pihak penyewa tidak melaksanakan apa yang menjadi kewajibannya maka pihak yang menyewakan dapat menuntut untuk meminta pelaksanaan perjanjian, atau meminta ganti kerugian ataupun bisa kedua-duanya yaitu meminta pelaksanaan disertai dengan ganti rugi

    Mass flow in the interacting binary TX Ursae Majoris

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    Twenty-two far-ultraviolet and 23 near-ultraviolet high resolution IUE spectra of the interactive Algol-type binary TX Ursae Majoris (B8 V + F-K III-IV) were analyzed in order to determine the nature of the mass flow occurring in this system. Absorption features due to high-temperature ions of Si IV, C IV, and N V are always present. The resonance lines of Al III, Fe II, Mg II and Si IV show strong phase and secular variations indicative of gas streaming and circumstellar/circumbinary material. Radial velocities as high as 500 to 600 km/sec are present. The gas flow is particularly prominent in 1985 between phases 0.7 and 0.0. The system is more active than U Sagittae and as active as U Cephei

    Dynamics of Magnetic Defects in Heavy Fermion LiV2O4 from Stretched Exponential 7Li NMR Relaxation

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    7Li NMR measurements on LiV2O4 from 0.5 to 4.2 K are reported. A small concentration of magnetic defects within the structure drastically changes the 7Li nuclear magnetization relaxation versus time from a pure exponential as in pure LiV2O4 to a stretched exponential, indicating glassy behavior of the magnetic defects. The stretched exponential function is described as arising from a distribution of 7Li nuclear spin-lattice relaxation rates and we present a model for the distribution in terms of the dynamics of the magnetic defects. Our results explain the origin of recent puzzling 7Li NMR literature data on LiV2O4 and our model is likely applicable to other glassy systems.Comment: Four typeset pages including four figure

    A formulation of the Yang-Mills theory as a deformation of a topological field theory based on background field method and quark confinement problem

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    By making use of the background field method, we derive a novel reformulation of the Yang-Mills theory which was proposed recently by the author to derive quark confinement in QCD. This reformulation identifies the Yang-Mills theory with a deformation of a topological quantum field theory. The relevant background is given by the topologically non-trivial field configuration, especially, the topological soliton which can be identified with the magnetic monopole current in four dimensions. We argue that the gauge fixing term becomes dynamical and that the gluon mass generation takes place by a spontaneous breakdown of the hidden supersymmetry caused by the dimensional reduction. We also propose a numerical simulation to confirm the validity of the scheme we have proposed. Finally we point out that the gauge fixing part may have a geometric meaning from the viewpoint of global topology where the magnetic monopole solution represents the critical point of a Morse function in the space of field configurations.Comment: 45 pages, 3 figures included in LaTe
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