2003/07/22 by Davide Controzzi, D. Controzzi, Giuseppe Mussardo +1 · 2 citations
Chemistry · Mathematics · Physics and Astronomy · #Advanced NMR Techniques and Applications #Combinatorics #Mathematics #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Sigma #Spectrum (functional analysis) #Term (time) #Theoretical and Computational Physics #cond-mat #hep-lat #hep-th
paper · pdf · doi:10.1103/physrevlett.92.021601
published as Phys.Rev.Lett. 92 (2004) 021601 · 4 pages REVTEX4, 2 figures reference added,corrected typos
arxiv created 2003/07/22 · openalex publication_date 2004/01/15 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Form factor perturbation theory is applied to study the spectrum of the O(3) nonlinear sigma model with the topological term in the vicinity of \ensuremathθ=\ensuremathπ. Its effective action near this value is given by the nonintegrable double sine-Gordon model. Using previous results by Affleck and the explicit expressions of the form factors of the exponential operators e^\ifmmode±\else\textpm\fii√8\ensuremathπ\ensuremathφ(x), we show that the spectrum consists of a stable triplet of massive particles for all values of \ensuremathθ and a singlet state of higher mass. The singlet is a stable particle only in an interval of values of \ensuremathθ close to \ensuremathπ, whereas it becomes a resonance below a critical value \ensuremathθc.