Noncompact Lattice Simulations of SU(2) Gauge Theory

Wilson loops have been measured at strong coupling, $\beta=0.5$, on a $12^4$ lattice in noncompact simulations of pure SU(2) without gauge fixing. There is no sign of quark confinement.Comment: 4 pages, UNM-93-nl

Gauge Invariance and Confinement in Noncompact Simulations of SU(2)

Wilson loops have been measured at strong coupling, $\beta=0.5$, on a $12^4$ lattice in a noncompact simulation of pure SU(2) in which random compact gauge transformations impose a kind of lattice gauge invariance. The Wilson loops suggest a confining potential.Comment: 3 pages, requires PiCTeX, talk presented at Lattice '93, UNM-gicns

Proteins Wriggle

We propose an algorithmic strategy for improving the efficiency of Monte Carlo searches for the low-energy states of proteins. Our strategy is motivated by a model of how proteins alter their shapes. In our model when proteins fold under physiological conditions, their backbone dihedral angles change synchronously in groups of four or more so as to avoid steric clashes and respect the kinematic conservation laws. They wriggle; they do not thrash. We describe a simple algorithm that can be used to incorporate wriggling in Monte Carlo simulations of protein folding. We have tested this wriggling algorithm against a code in which the dihedral angles are varied independently (thrashing). Our standard of success is the average root-mean-square distance (rmsd) between the alpha-carbons of the folding protein and those of its native structure. After 100,000 Monte Carlo sweeps, the relative decrease in the mean rmsd, as one switches from thrashing to wriggling, rises from 11% for the protein 3LZM with 164 amino acids (aa) to 40% for the protein 1A1S with 313 aa and 47% for the protein 16PK with 415 aa. These results suggest that wriggling is useful and that its utility increases with the size of the protein. One may implement wriggling on a parallel computer or a computer farm.Comment: 12 pages, 2 figures, JHEP late

Noncompact Gauge-Invariant Simulations of U(1), SU(2), and SU(3)

We have applied a new gauge-invariant, noncompact, Monte Carlo method to simulate the $U(1)$, $SU(2)$, and $SU(3)$ gauge theories on $8^4$ and $12^4$ lattices. The Creutz ratios of the Wilson loops agree with the exact results for $U(1)$ for $\beta \ge 0.5$ apart from a renormalization of the charge. The $SU(2)$ and $SU(3)$ Creutz ratios robustly display quark confinement at $\beta = 0.5$ and $\beta = 2$, respectively. At much weaker coupling, the $SU(2)$ and $SU(3)$ Creutz ratios agree with perturbation theory after a renormalization of the coupling constant. For $SU(3)$ the scaling window is near $\beta = 2$, and the relation between the string tension $\sigma$ and our lattice QCD parameter $\Lambda_L$ is $\sqrt{\sigma} \approx 5 \Lambda_L$.Comment: For U(1), we switched from beta = 2 / g^2 to beta = 1 / g^2; 3 pages; latex and espcrc2.sty; one figure generated by PiCTeX; our contribution to Lattice '9

Learning about spin-one-half fields

It is hard to understand spin-one-half fields without reading Weinberg. This paper is a pedagogical footnote to his formalism with an emphasis on the boost matrix, spinors, and Majorana fields.Comment: Fixed typo in this 19-page pedagogical paper on spinors and Majorana and Dirac field

Supersymmetry without Grassmann Variables

Supersymmetry transformations may be represented by unitary operators in a formulation of supersymmetry without numbers that anti-commute. The physical relevance of this formulation hinges on whether or not one may add states of even and odd fermion number, a question which soon may be settled by experiment.Comment: 8 pages, JHEP styl

The Sadhu

Short story about an Australian woman of Indian descent visiting India and being taken by a friend to meet a sadhu

Affective Terrains: Art, War, and National Belonging

This paper examines how cultural representations affirm national belonging within the context of Canada’s involvement in the War on Terror. To do this, it takes as its central case study an exhibition of official war art, 11 Artists for 11/11 (2012), which was mounted on public display in celebration of Remembrance Day. This paper approaches the exhibition and the works included in it by addressing their representative and non-representative (or affective) qualities, in order to think through the ways in which visual narratives of military history participate in shaping sentimental attachments to Canadian identity and being Canadian