The Maximal Abelian Gauge, Monopoles, and Vortices in SU(3) Lattice Gauge Theory

We report on calculations of the heavy quark potential in SU(3) lattice gauge theory. Full SU(3) results are compared to three cases which involve gauge-fixing and projection. All of these start from the maximal abelian gauge (MAG), in its simplest form. The first case is abelian projection to U(1)xU(1). The second keeps only the abelian fields of monopoles in the MAG. The third involves an additional gauge-fixing to the indirect maximal center gauge (IMCG), followed by center projection to Z(3). At one gauge fixing/configuration, the string tensions calculated from MAG U(1)xU(1), MAG monopoles, and IMCG Z(3) are all less than the full SU(3) string tension. The projected string tensions further decrease, by approximately 10%, when account is taken of gauge ambiguities. Comparison is made with corresponding results for SU(2). It is emphasized that the formulation of the MAG is more subtle for SU(3) than for SU(2), and that the low string tensions may be caused by the simple MAG form used. A generalized MAG for SU(3) is formulated.Comment: 22 pages, latex, 2 postscript figures. Replaced version has added data at beta=6.0, analysis of Gribov ambiguities, extended tables of results, discussion of scalin

The Spatial String Tension in the Deconfined Phase of the (3+1)-Dimensional SU(2) Gauge Theory

We present results of a detailed investigation of the temperature dependence of the spatial string tension in SU(2) gauge theory. We show, for the first time, that the spatial string tension is scaling on the lattice and thus is non-vanishing in the continuum limit. It is temperature independent below Tc and rises rapidly above. For temperatures larger than 2Tc we find a scaling behaviour consistent with sigma_s(T) = 0.136(11) g^4(T) T^2, where g(T) is the 2-loop running coupling constant with a scale parameter determined as Lambda_T = 0.076(13) Tc.Comment: 8 pages (Latex, shell archive, 3 PostScript figures), HLRZ-93-43, BI-TP 93/30, FSU-SCRI-93-76, WUB 93-2

bbˉb\bar b Description with a Screened Potential

Recent lattice QCD calculations suggest a rather abrupt transition in the confinig potential from a linear to a constant behavior. We analyze the effects of such a fast deconfinement in the simplest non-relativistic system, bottomonium.Comment: 4 pages. Presented at MENU04, Beijing 2004. To be published by IJMP

Lattice energy sum rules and the trace anomaly

We show that the additional contribution to the Michael lattice energy sum rule for the static quark-antiquark potential, pointed out recently, can be identified with the contribution to the field energy arising from the trace anomaly of the energy momentum tensor. We also exlicitely exhibit the anomalous contribution to the field energy in the sum rule for the glueball mass obtained recently by Michael.Comment: 8 pages, plain TeX, no figures; text & abstract extended. Includes glueball energy sum rul

What is it like to learn and participate in rhizomatic MOOCs? a collaborative autoethnography of #RHIZO14

In January 2014, we participated in a connectivist-style massive open online course (cMOOC) called "Rhizomatic Learning – The community is the curriculum" (#rhizo14). In rhizomatic learning, teacher and student roles are radically restructured. Course content and value come mostly from students; the teacher, at most, is a curator who provides a starting point and guidance and sometimes participates as a learner. Early on, we felt that we were in a unique learning experience that we wanted to capture in writing. Explaining #rhizo14 to others without the benefit of traditional processes, practices, roles, or structures, however, presented a challenge. We invited participants to contribute narratives to a collaborative autoethnography (CAE), which comprises an assortment of collaborative Google Docs, blog posts by individuals, and comments on those documents and posts. This strategy afforded insight into what many participants found to be a most engaging course and what for some was a transformative experience. In discussing the findings from the CAE, our intent is to benefit others interested in rhizomatic learning spaces such as cMOOCs. This authoethnography specifically addresses gaps both in the understanding of the learner experience in cMOOCs and in the nature of rhizomatic learning

The scalar and tensor glueballs in the valence approximation

We evaluate the infinite volume, continuum limit of $0^{++}$ and $2^{++}$ glueball masses in the valence approximation. We find $m_{0^{++}} = 1740 \pm 71$~MeV and $m_{2^{++}} = 2359 \pm 128$~MeV, consistent with the interpretation of $f_0 ( 1710 )$ as the lightest scalar glueball.Comment: (talk presented by A. Vaccarino at Lattice 93) 3 pages of PostScript in uufiles compressed form. IBM-HET-94-

Cylindrically Symmetric Inhomogeneous Universes with a Cloud of Strings

Cylindrically symmetric inhomogeneous string cosmological models are investigated in presence of string fluid as a source of matter. To get the three types of exact solutions of Einstein's field equations we assume $A = f(x)k(t)$, $B = g(x)\ell(t)$ and $C = h(x)\ell(t)$. Some physical and geometric aspects of the models are discussed.Comment: 9 page

A Tachyonic Gluon Mass: Between Infrared and Ultraviolet

The gluon spin coupling to a Gaussian correlated background gauge field induces an effective tachyonic gluon mass. It is momentum dependent and vanishes in the UV only like 1/p^2. In the IR, we obtain stabilization through a positive m^2_{conf}(p^2) related to confinement. Recently a purely phenomenological tachyonic gluon mass was used to explain the linear rise in the q\bar q static potential at small distances and also some long standing discrepancies found in QCD sum rules. We show that the stochastic vacuum model of QCD predicts a gluon mass with the desired properties.Comment: 10 pages LaTeX, 2 figures using eps

Gluon propagator, triple gluon vertex and the QCD coupling constant

We study the UV-scaling of the flavorless gluon propagator in the Landau gauge in an energy window up to 9 GeV. Dominant hypercubic lattice artifacts are eliminated. A large set of renormalization schemes is used to test asymptotic scaling. We compare with our results obtained directly from the triple gluon vertex. We end-up with \Lambda_{\bar{\rm{MS}}} = 318(12)(5) MeV and 292(5)(15) MeV respectively for these two methods, compatible which each other but significantly above the Schrodinger method estimate.Comment: 3 pages, LaTeX with two figures; presented at LATTICE9