Dresden 2011 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 62: CE: Low-dimensional Systems - Models 2
TT 62.4: Talk
Friday, March 18, 2011, 11:15–11:30, HSZ 105
Excitations and spectral densities of the one-dimensional Ising model in a field — •Marc Daniel Schulz and Kai Phillip Schmidt — Lehrstuhl für Theoretische Physik I, TU Dortmund, 44221 Dortmund, Germany
The one-dimensional quantum Ising model in a transverse field is a well-studied model in theoretical physics, which was solved exactly more than 40 years ago. 30 years ago, the prediction of the existence of a certain number of bound states at the critical point in the presence of an infinitesimal longitudinal field was made by integrable field theory. Here we study the excitation spectra and the spectral densities of the Ising model in a transverse and a longitudinal field, containing the physics of free and confined quasi-particles. To this end, we derive effective low-energy models for the low- and for the high-field case by means of perturbative and graph-based continuous unitary transformations. Our calculations are expected to be relevant for recent inelastic neutron scattering measurements on the quasi one-dimensional compound CoNb2O6 which is believed to be effectively described by an one-dimensional Ising model in a field.