title: Excitation spectrum of d-wave Fermi surface deformation.
abstract: Several instabilities competing with the d-wave singlet pairing were proposed for high-Tc cuprates. One of them is the d-wave Fermi surface deformation (dFSD), which is generated by forward scattering. In this Letter, correlation functions of the dFSD are calculated within the random phase approximation. In the normal state, the excitation spectrum shows a low energy peak, which smoothly connects to critical fluctuations of the dFSD at lower temperature. The competition with the d-wave pairing, however, blocks the critical fluctuations. The whole spectral weight is transferred to high energy and a pronounced peak appears there in the d-wave pairing state. This peak is an overdamped collective mode of the dFSD and can grow to become a resonance mode at moderate finite wave vectors.
authors.affiliation: RIKEN (The Institute of Physical and Chemical Research), Wako, Saitama 351-0198, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamase