Preliminary evidence for UA(1) breaking in QCD from lattice calculations |
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Authors: | P. Di Vecchia K. Fabricius G.C. Rossi G. Veneziano |
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Affiliation: | Physics Department, University of Wuppertal, Wuppertal, FRG;Istituto di Fisica dell''Università Rome and INFN, Sezione di Roma, Italy;CERN, Geneva, Switzerland |
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Abstract: | We suggest a simple definition of the topological charge density Q(x) in the lattice Yang-Mills theory and evaluate A≡∝d4x〈Q(x)Q(0)〉 in SU(2) by Monte Carlo simulation. The “data” interpolate well between the strong and weak coupling expansions, which we compute to order g?12 and g6, respectively. After subtraction of the perturbative tail, our points exhibit the expected asymptotic freedom behaviour giving , K being the SU(2) quarkless string tension. Although a larger value for would be preferable, we are led to conclude (at least tentatively) that the UA(1) problem of QCD is indeed solved perturbatively in the quark loop expansion. |
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