By using the gauge-gravity duality, we investigate the correlation function
of flavored fermion in the Dpβ/Dp+4β model as top-down
approaches of holographic QCD for p=4,3. The bulk spinor, as the source of
the flavored fermion in QCD, is identified to the worldvolume fermion on the
flavor Dp+4β-branes and the standard form of its action can be
therefore obtained by the T-duality rules in string theory. Keeping this in
hand, we afterwards generalize the prescription for two-point correlation
function in AdS/CFT dictionary into general D-brane backgrounds and apply it to
the case of p=4,3, i.e. the D4/D8 and D3/D7 approach respectively.
Resultantly, our numerical calculation with the bubble background always
displays discrete peaks in the correlation functions which imply the bound
states created by the flavored fermions as the confinement in QCD. With the
black brane background, the onshell condition illustrated by the correlation
function covers basically the dispersion curves of fermion obtained by the hard
thermal loop approximation in the hot medium. In this sense, we conclude
remarkably that our top-down approach in this work could reveal the fundamental
properties of QCD both in the confined and deconfined phase.Comment: 41 pages; 11 figures; 1 table; fix Figure 7 and Figure 1