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 σ(-V)≠σ(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*>Tc. We argue that the pseudogap structure has to exhibit a particle-hole asymmetry. This asymmetry may eventually depend on the boson concentration