Pseudogap in underdoped high- T c superconductors in the framework of the boson-fermion model

The question of whether the pseudogap in high-${T}_{c}$ cuprates is related to superconducting precursor effects or to the existence of extrinsic bosonic massive excitations is investigated on the basis of the boson-fermion model. The characteristic three-peak structure of the electronic spectral function and the temperature-dependent Fermi vector derived here are signatures for a two-component scenario which can be tested by angle-resolved photoemission spectroscopy and inverse photoemission spectroscopy experiments.