4,614 research outputs found

    DBI Action from Closed Strings and D-brane second Quantization

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    Brane-like vertex operators play an important role in a worldsheet formulation of D-branes and M-theory. In this paper we derive the DBI D-brane action from NSR closed string sigma-model with brane-like states. We also show that these operators carry RR charges and define D-brane wavefunctions in a second quantized formalism.Comment: 16 pages, latex, typos corrected, BRST nontriviality condition (9) for closed string vertices is amende

    Equivalence of the Beta-function of the Variational Approach to that of QCD

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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' is seen to originate in the renormalisation of a Coulomb interaction by a transverse gluon. The lesser screening contribution of `1/3' is seen to originate in processes involving transverse gluon interactions. It is thus apparent how the variational ansatz must be developed to capture the full running of the QCD coupling constant.Comment: 35 pages, 11 figures, LaTe

    About some exact solutions for 2+1 gravity coupled to gauge fields

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    Some exact static solutions for Einstein gravity in 2+1 dimensions coupled to abelian gauge field are discussed. Some of these solutions are three-dimensional analogs of the Schwarzschild black holes. The metrics in the regions inside and outside the horison are connected by the changing of the Planck mass sign.Comment: 10 page

    A variational approach to the QCD wavefunctional: Calculation of the QCD beta-function

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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, transverse gluons (which contribute the 1/3) are omitted. The renormalisation procedure is understood in terms of `tadpole' and `horse-shoe' Feynman diagrams which must be interpreted with a non-local propagator.Comment: 23 pages, LaTex, 2 fig
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