@article{Tchernyshyov2000WhereIT,
title={Where is the pi particle},
author={Oleg Tchernyshyov and M. R. Norman and Andrey V. Chubukov},
journal={Physical Review B},
year={2000}
}

We discuss the interplay of particle-particle and particle-hole spin-triplet channels in high-T_c superconductors using a quasiparticle dispersion motivated by angle-resolved photoemission. Within a generalized RPA, we find a well defined antibound state of two holes, the pi resonance of Demler and Zhang, as well as a bound state of a particle and a hole, the spin exciton. We show that the energy of the pi resonance always exceeds 2 Delta, twice the maximum d-wave gap, therefore the neutron… Expand

We review recent experimental and theoretical results on the interaction between single-particle excitations and collective spin excitations in the superconducting state of high-Tc cuprates. We… Expand

We argue that the pseudogap phase may be an attribute of the non-BCS pairing of quantum-critical, diffusive fermions near the antiferromagnetic quantum critical point. We derive and solve a set of… Expand

A comprehensive survey of the cuprate, heavy-fermion and iron-based superconductors shows a universal linear relationship between their magnetic resonance energy and superconducting gap. This result… Expand