  We investigate the quasiparticle excitation of the bilayer quantum Hall (QH)
system at total filling factor $\nu_{\mathrm{T}} = 1$ in the limit of
negligible interlayer tunneling under tilted magnetic field. We show that the
intrinsic quasiparticle excitation is of purely pseudospin origin and solely
governed by the inter- and intra-layer electron interactions. A model based on
exciton formation successfully explains the quantitative behavior of the
quasiparticle excitation gap, demonstrating the existence of a link between the
excitonic QH state and the composite fermion liquid. Our results provide a new
insight into the nature of the phase transition between the two states.
