Spectral function of superconducting cuprates near optimal doping

We argue that the unusual peak-dip-hump features observed in photoemission experiments on Bi2212 at T ≪ T_c can be explained by the interaction of the fermionic quasiparticles with overdamped spin fluctuations. We show that the strong spin-fermion interaction combined with the feedback effect on the spin damping due to superconductivity yields the fermionic spectral function A(k_F, ω) which simultaneously displays a quasiparticle peak at ω = Δ and a broad maximum (hump) at ω ≫ Δ. In between the two regimes, the spectral function has a dip at Δ ∼ 2Δ. We argue that our theory also explains the tunneling data.