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AbstractAbstract

[en] Though the Lagrangian of quantum chromodynamics is well known, it has proven extremely difficult to derive precisely all its consequences to compare with experiment. Approximations based on physical reasoning must be made. One method is to calculate the effective action for some particularly simple configuration of gluons and use this to analyze an arbitrary system of interacting quarks. In the first chapter, the one-loop correction to the gluon propagator is computed in two different ways - dimensional regularization and Schwinger's proper time method. The renormalization mass parameters appearing in the two treatments can then be related and the exact one-loop effective action of a constant gluon field can be expressed in terms of the experimentally determinable Λ/sub MS/. In the following chapter, the interaction of a heavy quark-antiquark pair governed by this action is considered and it is shown how the spectrum, and, in particular, the spin splittings of the bound states can be found. Due to asymptotic freedom, a massive quarkonium is analogous to a non-relativistic electromagnetic system. At short distances, the results are the same as those derived from perturbation theory though, for example, the hyperfine structure arises in a different way. At large distances, the analysis is qualitative but our results agree with the predictions of strong coupling lattice gauge theories

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Source

1984; 86 p; University Microfilms Order No. 84-19,716; Thesis (Ph. D.).

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Report

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Thesis/Dissertation

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AbstractAbstract

[en] The massless Schwinger model, with left-handed and right-handed fermions coupled differently to an abelian gauge field, is consistent if a parameter exceeds a critical number. With the fermions given a gauge-invariant mass, the critical number is twice as large. The low-energy theory is of the sine-Gordon form in the strong-coupling limit. (orig.)

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GRANT SERC NG17094

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Journal Article

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AbstractAbstract

[en] Small-angle neutron scattering technique has been employed to investigate the evolution of pore morphology during the initial and the intermediate stages of sintering in ZrO

_{2}-3 mol% Y_{2}O_{3}. These results show that although there is a reduction in the porosity due to the elimination of the pores, the average growth in the pore size takes place during the sintering. This trend in pore growth corroborates the results of computer simulation based on the Potts model. The SANS data has been analyzed in the light of the polydisperse spherical pore modelPrimary Subject

Source

S0925838803004407; Copyright (c) 2003 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)

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Journal Article

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AbstractAbstract

[en] An analytical expression for the structure factor has been derived by using a square well potential as a perturbation over the hard sphere potential. The calculated values for the structure factors of liquid magnesium and cadmium are in good agreement with experiments. (Auth.)

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Journal Article

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Chemical Physics Letters; v. 43(3); p. 455-456

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AbstractAbstract

[en] Following Bender et al., we apply the finite element method to a compact non-abelian system. We do a hamiltonian Monte Carlo on a 0 + 1 dimensional lattice and compare the results with those obtained by a finite difference method. For the kinetic energy, the Feynman-Hibbs prescription is followed and the finite element method is shown to be distinctly superior. (orig.)

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Secondary Subject

Source

CONTRACT PHY80-19754; CODEN: PYLBA.

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Journal Article

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Phys. Lett., B; ISSN 0370-2693; ; v. 129(3/4); p. 239-242

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AbstractAbstract

[en] Analysis of the low energy spectra of a large number of odd-odd nuclei has been done to obtain information on the contribution of the last odd proton and neutron to the moment of inertia. (author)

Primary Subject

Source

Department of Atomic Energy, Bombay (India); 279 p; 1981; p. 173-174; Department of Atomic Energy; Bombay (India); Nuclear physics and solid state physics symposium; Bombay (India); 28 Dec 1981 - 1 Jan 1982

Record Type

Book

Literature Type

Conference; Numerical Data

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AbstractAbstract

[en] We formally derive the spin-orbit and spin-spin potentials in heavy quarkonium from a general effective action. We then specialize to the perturbative effective action for short distances and obtain agreement with the lowest-order Bethe-Salpeter results, including the contact spin-spin interaction which arises in an unusual way in our paper. For large distances, the leading log model is used. Though it is not possible to solve this analytically, some interesting qualitative features are pointed out. (orig.)

Primary Subject

Source

CONTRACT PHY-80-19754; CODEN: NUPBB.

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Journal Article

Journal

Nuclear Physics. B; ISSN 0550-3213; ; v. 254(3/4); p. 678-696

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AbstractAbstract

[en] ZrO

_{2}-8 mol% Y_{2}O_{3}powder compact prepared by citric acid gel route has been sintered at different temperatures to achieve different porosity levels. The effect of sintering temperature on the pore morphology and pore size distribution in the same has been investigated using small-angle neutron scattering (SANS). The results reveal pore size growth with increase in the sintering temperature, although a reduction in the porosity occurs because of the elimination of pores from the system. The quantitative analysis of the SANS data has been carried out in the light of the polydisperse globular pore model. The growth of the average size of the pores with sintering temperature could be fitted to an Arrhenius type growth. The necessity of considering a realistic model approximation in interpreting the data has also been dwelt uponPrimary Subject

Source

S0925838803006133; Copyright (c) 2003 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)

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AbstractAbstract

[en] Quantum field theories on the surface of a four-dimensional sphere are considered. The Hamiltonian is rotation invariant and its eigenvalues are discrete. Scalar, vector, and spinorial functions on S

^{3}are discussed. The most general Lagrangians for Dirac, Weyl, and Majorana fermions are derived. They are different from the ones in existing literature. The wave functions and propagator are obtained and formulas for matrix elements involving spinors are presented. The discrete symmetries: parity, charge conjugation, and time reversal: are described. The Lagrangian in R x S^{3}transforms in a nontrivial way under these. Finally, the fermionic Lagrangian is rederived using the tetrad formalism, and conformal transformations are discussed. This leads to a generalization of the formalism to a time-dependent radius of curvature. As a particular case, a new Lagrangian for de Sitter space is obtained, which, however, is not invariant under the full de Sitter groupPrimary Subject

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AbstractAbstract

[en] Global N=1 supersymmetry is implemented on the surface of a four-dimensional sphere, in order to obtain a rotationally invariant and infrared-regulated version of such theories. We find that only R-invariant theories have supersymmetric actions in this space, and that the R-operator explicitly appears in the supersymmetry algebra (although the flat space superalgebra is recovered in the limit of large radius). Going to RxS

^{3}therefore provides a rationale for only considering R-invariant theories, as is usually done for phenomenological reasons in flat space. The vacuum structure is analyzed at the tree level in various theories, and in most cases, it turns out to be simpler than in flat space. Supersymmetry breaking is considered, and it is found necessary to redefine Witten's index. This is due to the unusual superalgebra in RXS^{3}, and its consequence, that the number of bosonic and fermionic states are not equal at any energy level. Finally, superspace is defined, and the scalar and vector multiplets are described in terms of chiral superfields. The supersymmetric transformations and lagrangian can be reexpressed in this language. (orig.)Primary Subject

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Journal Article

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BOSONS, CHIRALITY, COMMUTATION RELATIONS, FERMIONS, FOUR-DIMENSIONAL CALCULATIONS, GLOBAL ANALYSIS, GRADED LIE GROUPS, INFRARED DIVERGENCES, LAGRANGIAN FIELD THEORY, MATHEMATICAL SPACE, PARTICLE MULTIPLETS, RENORMALIZATION, ROTATIONAL INVARIANCE, SCALAR FIELDS, SPACE-TIME, SPHERICAL CONFIGURATION, SPINOR FIELDS, SUPERSYMMETRY, SYMMETRY BREAKING, TOPOLOGICAL MAPPING, UNIFIED GAUGE MODELS, VACUUM STATES, VECTOR FIELDS

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