Dynamic structure factor of spin-1/2 chains with long-range interactions

We study the dynamic structure factor of spin-1/2 chains with long-range power-law decaying unfrustrated interactions by means of stochastic analytic continuation (SAC) of quantum Monte Carlo (QMC) imaginary-time data. I will explain different parametrizations of the spectral function S(q,ω) in the SAC method and their applications in the antiferromagnetic (AFM) and quasi long-range ordered (QLRO) phases. The spectral functions are observed to evolve from one with a sharp quasi-particle peak (magnon) in the AFM phase to an edge with power-law divergent form in the QLRO phase as the exponent governing the power-law decay of the interactions is changed. This study can serve as a bench-mark for SAC/QMC studies of systems with a transition from conventional to fractionalized quasi-particles, which we also plan to study in 2D systems.