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Journal of Physics C Solid State Physics

Spectral density method for the damping of boson elementary excitations in one-dimensional spin S chain

L. S. Campana, M. D’Ambrosio, Ugo Esposito

Published Nov 30, 1985• 2 citations
Publisher

Abstract

Damping effects of boson elementary excitations in the Dyson-Maleev representation of one-dimensional spin S chain using the spectral density method (SDM) are studied. For the spectral density the authors use the 'gaussian ansatz', and the reasonable results, obtained in the low-temperature limit, confirm that it is able to describe damping effects in the SDM.

DOI
10.1088/0022-3719/18/33/012

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Damping effects of boson elementary excitations in the Dyson-Maleev representation of one-dimensional spin S chain using the spectral density method (SDM) are studied. For the spectral density the authors use the 'gaussian ansatz', and the reasonable results, obtained in the low-temperature limit, confirm that it is able to describe damping effects in the SDM.
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Spectral density for the elementary excitation of the multichannel Kondo model is investigated at finite temperatures with the use of the Bethe-ansatz method. Our formulation is based on the method of Yang and Yang developed in one-dimensional interacting boson systems. In the orbital singlet case, the narrow peak structure develops in the low-energy region as the temperature is decreased, whereas in the underscreened case, the excitation spectrum exhibits a divergence property at zero excitation energy, irrespective of the temperature. In the overscreened case, in which the non-Fermi-liquid fixed point is stable in the ground state, the peak structure develops in the low-energy region and the weight at zero excitation energy increases as the temperature is decreased. We discuss characteristic properties of the excitation spectrum in connection with bulk properties.