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A meron cluster solution for the sign problem of the two-dimensional O(3) model

Frank Brechtefeld
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Abstract

The two-dimensional O(3) model at a vacuum angle theta=pi is investigated. This model has a severe sign problem. By a Wolff cluster algorithm an integer or half-integer topological charge is assigned to each cluster. The meron clusters (clusters with half-integer topological charge) are used to construct an improved estimator for the correlation function of two spins at theta=pi. Only configurations with 0 and 2 merons contribute to this correlation function. An algorithm, that generates configurations with only 0 and 2 merons, is constructed and numerical simulations at theta=pi are performed. The numerical results indicate the presence of long range correlations at theta=pi.

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Frank Brechtefeld. 2002-07-22. A meron cluster solution for the sign problem of the two-dimensional O(3) model. https://arxiv.org/abs/hep-lat/0207012

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