θ Vacuum: A matrix model

Romuald A. Janik, Maciej A. Nowak, Gábor Papp, Ismail Zahed

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

We model the effects of a large number of zero modes for Nf species of quarks at finite vacuum angle θ, using a matrix model with Gaussian weights constrained by the topological susceptibility and compressibility. The quenched free energy exhibits a cusp at θ < π that is sensitive to the accuracy of the numerical analysis and the maximum density of winding modes. Our results bear much in common with recent lattice simulations by Schierholz and others. The unquenched free energy exhibits similar sensitivities, but for small quark masses or a large density of zero modes the results are in agreement with those derived using anomalous Ward identities and effective Lagrangians.

Original languageEnglish
Pages (from-to)1297-1315
Number of pages19
JournalActa Physica Polonica B
Volume32
Issue number4
Publication statusPublished - Dec 1 2001

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Janik, R. A., Nowak, M. A., Papp, G., & Zahed, I. (2001). θ Vacuum: A matrix model. Acta Physica Polonica B, 32(4), 1297-1315.