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Sep 21, 2013
09/13

by
William E. Brown

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The variational ansatz for the ground state wavefunctional of QCD is found to capture the anti-screening behaviour that contributes the dominant `-4' to the beta-function and leads to asymptotic freedom. By considering an SU(N) purely gauge theory in the Hamiltonian formalism and choosing the Coulomb gauge, the origins of all screening and anti-screening contributions in gluon processes are found in terms of the physical degrees of freedom. The overwhelming anti- screening contribution of `-4'...

Source: http://arxiv.org/abs/hep-th/9711189v1

"A thesis submitted to the University of Alberta in partial fulfilment of the requirements for the degree of Master of Science"

Topics: Plant proteins, Amino acids

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Sep 19, 2013
09/13

by
William E. Brown; Ian I. Kogan

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We discuss three dimensional compact QED with a theta term due to an axionic field. The variational gauge invariant functional is considered and it is shown that the ground state energy is independent of theta in a leading approximation. The mass gap of the axionic field is found to be dependent upon theta, the mass gap of the photon field and the scalar potential. The vacuum expectation of the Wilson loop is shown to be independent of theta in a leading approximation, to obey the area law and...

Source: http://arxiv.org/abs/hep-th/9703128v2

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Sep 21, 2013
09/13

by
William E. Brown; Ian I. Kogan

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The beta-function is calculated for an SU(N) Yang-Mills theory from an ansatz for the vacuum wavefunctional. Direct comparison is made with the results of calculations of the beta-function of QCD. In both cases the theories are asymptotically free. The only difference being in the numerical coefficient of the beta-function, which is found to be -4 from the ansatz and -4+1/3 from other QCD calculations. This is because, due to the constraint of Gauss' law applied to the wavefunctional,...

Source: http://arxiv.org/abs/hep-th/9705136v2

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Sep 23, 2013
09/13

by
William E. Brown; James T. Liu; Hai-cang Ren

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Color superconductivity is a possible phase of high density QCD. We present a systematic derivation of the transition temperature, T_C, from the QCD Lagrangian through study of the di-quark proper vertex. With this approach, we confirm the dependence of T_C on the coupling g, namely $T_C \sim \mu g^{-5} e^{-\kappa/g}$, previously obtained from the one-gluon exchange approximation in the superconducting phase. The diagrammatic approach we employ allows us to examine the perturbative expansion of...

Source: http://arxiv.org/abs/hep-ph/9908248v2

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Sep 22, 2013
09/13

by
William E. Brown; James T. Liu; Hai-cang Ren

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At sufficiently high baryon densities, the physics of a dense quark-gluon plasma may be investigated through the tools of perturbative QCD. This approach has recently been successfully applied to the study of color superconductivity, where the dominant di-quark pairing interaction arises from one gluon exchange. Screening in the plasma leads to novel behaviour, including a remarkable non-BCS scaling of T_C, the transition temperature to the color superconducting phase. Radiative corrections to...

Source: http://arxiv.org/abs/hep-ph/0003199v2

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Sep 19, 2013
09/13

by
William E. Brown; James T. Liu; Hai-cang Ren

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Recent interest in the study of color superconductivity has focused on the regime of high baryon density where perturbative QCD may be employed. Based on the dominant one-gluon-exchange interaction, both the transition temperature and zero temperature gap have been determined to leading order in the coupling, g. While the leading non-BCS behavior, $T_C\sim\mu g^{-5}e^{-\kappa/g}$, is easily obtained, the pre-exponential factor has proved more difficult to evaluate. Focusing on the transition...

Source: http://arxiv.org/abs/hep-ph/9912409v1

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Sep 19, 2013
09/13

by
William E. Brown; Juan P. Garrahan; Ian I. Kogan; Alex Kovner

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We extend the gauge invariant variational approach of Phys. Rev. D52 (1995) 3719, hep-th/9408081, to theories with fermions. As the simplest example we consider the massless Schwinger model in 1+1 dimensions. We show that in this solvable model the simple variational calculation gives exact results.

Source: http://arxiv.org/abs/hep-th/9912136v1