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Michael Grady

Publications and source records attributed to Michael Grady.

23 records · Page 2Linked to original sources
arXiv1998

Gauge Invariant SO(3) - Z2 Monopoles as Possible Source of Confinement in SU(2) Lattice Gauge Theory

A gauge invariant procedure for extracting combined SO(3)-Z2 monopoles in positive-plaquette SU(2) lattice gauge theory is shown. When these monopoles are eliminated through a constraint, the theory deconfines for all $β$ on $12^4$ and $20^4$ lattices even in the strong coupling limit, despite a rather strong average plaquette of around 0.64. This corresponds to an effective Wilson $β$ of 2.45, at which Wilson-action lattices would be far into the confining region. This suggests that Wilson-action confinement may be a strong-coupling lattice artifact; the continuum limit may not confine.

hep-lat↗
arXiv1998

Monopole Loop Suppression and Loss of Confinement in Restricted Action SU(2) Lattice Gauge Theory

The effect of restricting the plaquette ($1\times 1$ Wilson loop) to be greater than a certain cutoff is studied. The action considered is the standard Wilson action with the addition of the plaquette restriction, which does not affect the continuum limit. A deconfining phase transition occurs as the cutoff is raised, even in the strong coupling limit. Abelian-projected monopoles in the maximal abelian gauge are strongly suppressed by the action restriction. Analysis of the steeply declining monopole loop distribution function indicates that for cutoffs $c > 0.5$, large monopole loops which are any finite fraction of the lattice size do not exist in the infinite lattice limit. This would seem to imply the theory lacks confinement, which is consistent with a fixed point behavior seen in the normalized fourth cumulant of the Polyakov loop.

hep-lat↗
arXiv1996

Deconfinement from Action Restriction

The effect of restricting the plaquette to be greater than a certain cutoff value is studied. The action considered is the standard Wilson action with the addition of a plaquette restriction, which should not affect the continuum limit of the theory. In this investigation, the strong coupling limit is also taken. It is found that a deconfining phase transition occurs as the cutoff is increased, on all lattices studied (up to $20^4$). The critical cutoff on the infinite lattice appears to be around 0.55. For cutoffs above this, a fixed point behavior is observed in the normalized fourth cumulant of the Polyakov loop, suggesting the existence of a line of critical points corresponding to a massless gluon phase, not unlike the situation in compact U(1). The Polyakov loop susceptibility also appears to be diverging with lattice size at these cutoffs. A strong finite volume behavior is observed in the pseudo-specific heat. It is discussed whether these results could still be consistent with the standard crossover picture which precludes the existence of a deconfining phase transition on an infinite symmetric lattice.

hep-lat↗
arXiv1995

Finite Temperature Phase Transition in SU(2) Lattice Gauge Theory with Extended Action

We study the three dimensional fundamental-adjoint $SU(2)$ lattice gauge theory at finite temperature by Monte Carlo simulations. We find that the finite temperature deconfinement phase transition line joins the first order bulk phase transition line at its endpoint. Moreover, across the bulk transition line, the Polyakov loop undergoes a discontinuous jump implying the existence of both confining and deconfining phases on its two sides. Implications for universality and the nature of the confining-deconfining transition are discussed.

hep-lat↗