Signatures of unstable particles in finite volume spectra
Department of Theoretical Physics, Eötvös Loránd University
Lundi 20/11/2006, 11:00
Salle Claude Itzykson, Bât. 774, Orme des Merisiers
We develop methods to extract resonance widths from finite volume
spectra of 1+1 dimensional quantum field theories. Our two methods are
based on Luscher's description of finite size corrections, and are
dubbed the Breit-Wigner and the improved "mini-Hamiltonian" method,
respectively. We establish a consistent framework for the finite
volume description of sufficiently narrow resonances that takes into account
the finite size corrections and mass shifts properly. Using
predictions from form factor perturbation theory, we test the two methods against
finite size data from truncated conformal space approach, and find
excellent agreement which confirms both the theoretical framework and
the numerical validity of the methods. Although our investigation is
carried out in 1+1 dimensions, the extension to physical (3+1)
space-time dimensions is straightforward, given sufficiently accurate
finite volume spectra.
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