Tuesday, February 21, 2012

1202.4381 (Falk Zimmermann et al.)

Vacuum structure and string tension in Yang-Mills dimeron ensembles    [PDF]

Falk Zimmermann, Hilmar Forkel, Michael Muller-Preussker
We numerically simulate ensembles of SU(2) Yang-Mills dimeron solutions with
a statistical weight determined by the classical action and perform a
comprehensive analysis of their properties. In particular, we examine the
extent to which these ensembles capture topological and confinement properties
of the Yang-Mills vacuum. This further allows us to test the classic picture of
meron-induced quark confinement as triggered by dimeron dissociation. At small
bare couplings, spacial, topological-charge and color correlations among the
dimerons generate a short-range order which screens topological charges. With
increasing coupling this order weakens rapidly, however, in part because the
dimerons gradually dissociate into their meron constituents. Monitoring
confinement properties by evaluating Wilson-loop expectation values, we find
the growing disorder due to these progressively liberated merons to generate a
finite and (with the coupling) increasing string tension. The short-distance
behavior of the static quark-antiquark potential, on the other hand, is
dominated by small, "instanton-like" dimerons. String tension, action density
and topological susceptibility of the dimeron ensembles in the physical
coupling region turn out to be of the order of standard values. Hence the above
results demonstrate without reliance on weak-coupling or low-density
approximations that the dissociating dimeron component in the Yang-Mills vacuum
can indeed produce a meron-populated confining phase. The density of
coexisting, hardly dissociated and thus instanton-like dimerons seems to remain
large enough, on the other hand, to reproduce much of the additional
phenomenology successfully accounted for by non-confining instanton vacuum
models. Hence dimeron ensembles should provide an efficient basis for a rather
complete description of the Yang-Mills vacuum.
View original: http://arxiv.org/abs/1202.4381

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