Showing papers by "Heinrich Leutwyler published in 1991"
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TL;DR: The determination of the σ-term from πN scattering is critically examined in this paper, where low-energy precision measurements are needed to clarify discrepancies in experimental data and to reduce the uncertainty in the strangeness content for which y ≅ 0.2.
625 citations
TL;DR: In this paper, the authors used dispersion relations to calculate the nucleon from factor of the scalar operator u u+d d and showed that the corresponding mean square radius is remarkably large.
181 citations
TL;DR: In this paper, the authors analyze temperature effects and volume effects in the correlation functions of the vector and axial quark charges and of the winding number, using the large-volume expansion of the effective low-energy theory.
72 citations
TL;DR: In this article, the energy momentum tensor to order 4 in chiral perturbation theory was calculated and new terms not present in previous work entered the effective Lagrangian.
Abstract: We calculate the energy momentum tensor to orderE4 in chiral perturbation theory. New terms not present in previous work enter the effective Lagrangian. We describe these and estimate the values of the new coupling constants, using the results of a disperisve analysis of the π andK energy momentum tensors and relying on tensor meson dominance for the spin two component. In addition, we compare our findings with the predictions of known scalar meson dominance models of the conformal anomaly.
66 citations
TL;DR: In this article, the authors study the 4-component φ4 model in 4 dimensions in the broken phase where the Goldstone modes dominate the finite size effects and find very good agreement with the theoretically expected functional behaviour.
45 citations
TL;DR: In this article, the distribution of the mean field Φ = V−1∫ddxφ(x) at large volume was studied and the shape of the constraint effective potential in the scaling limit was calculated.
26 citations
TL;DR: For O(N)-symmetric spin models in the spontaneously broken phase, the distribution of the mean field Φ = V−1fddx φ(x) at large volume was studied in this paper.
21 citations
TL;DR: For O(n)-symmetric spin systems in the spontaneously broken phase enclosed in a finite volume V, the authors in this paper derived a large-volume expansion for the correlation functions of the projected field φp(x) = Φ · φ(x)/|Φ|c.
17 citations
TL;DR: In this paper, a scalar Higgs field in an expanding Robertson-Walker geometry was studied, using the real-time formulation of Semenoff and Weiss, and it was shown that the density matrix associated with the Hamiltonian at a sharp time describes a state for which perturbation theory is not renormalizable.
11 citations