Pairon spectral function for high-T_c cuprate superconductors

The pairon spectral function for the high-Tc cuprate superconductor YBa(2)Cu(3)O7-d has been evaluated through renormalized pairon frequency, analogous to the frequency (energy) of excited pairons. The exercise has been carried out with the help of many-body quantum dynamical Green's function theory via a model Hamiltonian that includes the effects of the electrons, phonons, impurities and anharmonic fields. The analysis of the obtained results reveals that renormalized pairon frequency progressively increases up to the critical temperature T-c and afterwards, instead of dropping to zero, it decreases smoothly with increasing temperature, capturing the essence of the pseudogap in high-Tc cuprates. A further analysis of temperature-dependent spectral function also establishes the presence of the pseudogap above Tc. The spectral function displays a conscious behavior with the variation of electron-phonon coupling constant (gk).