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The recently derived current algebra of classical non-linear sigma models on arbitrary Riemannian manifolds is extended to include the energy-momentum tensor. It is found that in two dimensions the energy-momentum tensor $\theta_{\mu\nu}$, the Noether current $j_\mu$ associated with the global symmetry of the theory and the composite field $j$ appearing as the coefficient of the Schwinger term in the current algebra, together with the derivatives of $j_\mu$ and $j$, generate a closed algebra. The subalgebra generated by the light-cone components of the energy-momentum tensor consists of two commuting copies of the Virasoro algebra, with central charge $\, c\!=\!0 $, reflecting the classical conformal invariance of the theory, but the current algebra part and the semidirect product structure are quite different from the usual Kac-Moody / Sugawara type construction.

1Robert's Rules of Order

By Henry M. Robert

Originally written in 1876 by Major Henry M. Robert of the US Army Corps of Engineers, <i>Robert's Rules of Order</i> is the most widely used authority in the United States today for "parliamentary law, based...upon the rules and practice of Congress" for "organizing and conducting the business of societies, conventions, and other deliberative assemblies." (Summary by TriciaG and from Preface)