Thermodynamics and tunneling spectroscopy in the pseudogap regime of the boson-fermion model

Motivated by the STM experimental data on Bi2Sr2CaCu2O8+x which indicate the tunneling conductance asymmetry sigma(-V) not equal sigma(V), we report that such a behavior can be explained in terms of the boson-fermion model. It has been shown in the recent studies, based on various selfconsistent techniques to capture the many-body effects, that the low energy spectrum of the boson-fermion model is featured by an appearance of the pseudogap at T* > T-c. We argue that the pseudogap structure has to exhibit a particle-hole asymmetry. This asymmetry may eventually depend on the boson concentration. (C) 2003 Elsevier Science B.V. All rights reserved.