Erhard Seiler

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Compact (ferroand antiferromagnetic) sigma-models and noncompact (hyperbolic) sigma-models are compared in a lattice formulation in dimensions d ≥ 2. While the ferroand antiferromagnetic models are essentially equivalent, the qualitative difference to the noncompact models is highlighted. The perturbative and the large N expansions are studied in both types(More)
According to the standard classification of Conformal Quantum Field Theory (CQFT) in two dimensions, the massless continuum limit of the O(2) model at the Kosterlitz-Thouless (KT) transition point should be given by the massless free scalar field; in particular the Noether current of the model should be proportional to (the dual of) the gradient of the(More)
We prove Guerra’s theorem, 4 bounds and Frohlich bounds in the Y, and $34 field theories. Among our technical results of interest is a proof that 2 # 0 in &* and that the spatially cutoff vacuum in Ye has a charge zero component. The two main inputs are Osterwalder-Schrader positivity in the spatial direction as well as in the time direction, and a finite(More)
In dimension D ≤ 2 the low temperature behavior of systems enjoying a continuous symmetry is dominated by super-instantons: classical configurations of arbitrarily low energy. Perturbation theory in the background of a super-instanton produces thermodynamic answers for the invariant Green’s functions that differ from the standard ones, but only in(More)
In this talk I give an overview of the work done during the last 15 years in collaboration with the late Adrian Patrascioiu. In this work we accumulated evidence against the commonly accepted view that theories with nonabelian symmetry – either two dimensional nonlinear σ models or four dimensional Yang-Mills theories – have the property of asymptotic(More)