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arXiv 0710.2380hep-lat
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QCD真空结构的几个方面

Aspects of QCD Vacuum Structure

Peter J. Moran, Derek B. Leinweber

摘要:

探讨了动力学费米子对QCD真空结构的影响。特别令人感兴趣的是拓扑电荷相关器,$<q(x) q(0) >$,其中在小$x$的负值揭示了一个符号交替分层结构的QCD真空的拓扑电荷密度。我们认为大$28^3 \times 96$格从MILC合作,并开发一个新的胶子定义的拓扑电荷密度,建立在一个新的过度改进的stout链接涂抹算法。该算法再现建立的结果,从重叠形式主义,旨在保持瞬子。我们研究在何种程度上发现的晶格上的瞬子样的对象。最后,我们研究了动力学海夸克自由度对拓扑结构的影响,发现随着动力学费米子自由度的引入,$<q(x)q(0)>$相关器中的负倾角和正的$<q(0)^2>$接触项的大小都增加了.这与基于电荷重整化和在手征极限中拓扑磁化率消失的预期是一致的。

英文摘要:

The impact of dynamical fermions on the vacuum structure of QCD is explored. Of particular interest is the topological charge correlator, $<q(x) q(0) >$, where negative values at small $x$ reveal a sign-alternating layered structure to the topological-charge density of the QCD vacuum. We consider large $28^3 \times 96$ lattices from the MILC collaboration, and develop a new gluonic definition of the topological charge density, founded on a new over-improved stout-link smearing algorithm. The algorithm reproduces established results from the overlap formalism and is designed to preserve instantons. We examine the extent to which instanton-like objects are found on the lattice. Finally, we investigate the effects of dynamical sea-quark degrees of freedom on topology and find that the magnitudes of the negative dip in the $<q(x)q(0)>$ correlator and the positive $<q(0)^2>$ contact term are both increased with the introduction of dynamical fermion degrees of freedom. This is in accord with expectations based on charge renormalization and the vanishing of the topological susceptibility in the chiral limit.

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