Threshold singularities in the dynamic response of gapless integrable models

Vadim Cheianov

Lancaster University, UK

I shall describe a method of an asymptotically exact treatment of threshold singularities in dynamic response functions of gapless integrable models. The method utilizes integrability to recast the original problem in terms of the low-energy properties of a certain deformed Hamiltonian. The deformed Hamiltonian is local, hence it can be analysed using the conventional field theory methods. The technique will be illustrated on an example of spinless fermions on a lattice with nearest-neighbors repulsion. The work was done in collaboration with M. Pustilnik.