  The Fourier-transform scanning tunneling spectroscopy (FTSTS) contains rich
signals related to the quasiparticle scattering interference and/or the
density-wave-like orders which are crucial in interpretation of the ground
states and the phase transitions in quasi-2D strongly correlated electron
systems such as cuprate and pnictide high-Tc superconductors. The octet model
has been used to describe the FTSTS data according to the simplified banana
band model of cuprates in superconducting ground state and worked well deep
inside the superconducting dome, but away from the superconducting ground state
the description starts to show severe limitations, such as appearance of
particle-hole asymmetry of the quasiparticle band as will be discussed later.
The first efforts to describe the FTSTS signals based on the fully-phased
Green's function-based quasiparticle scattering interference theory, however
lacked the full similarity to the FTSTS data, in part due to the lack of
accurate information on the tunneling and scattering matrix elements. In this
paper we discuss how the noise due to the potential disorder and the various
artifacts in the raw FTSTS data can be handled by a simple cross-sectional
analysis with an isotropic Gaussian averaging and modeling the set-point effect
by an energy-independent and position-dependent factor to the density of states
function. The result shows that in the cross-sectional presentation an enhanced
correlation exists between the FTSTS data and the theoretical simulation even
without the accurate model for the tunneling and the scattering matrix elements
and without the assumption for particle-hole symmetry, suggesting that it can
be a new starting point of a more robust quantum physical analysis framework
appropriate for the phase transition study in the high-Tc superconductors and
other strongly correlated electron systems.
