  We investigate the scattering problem of a two-particle composite system on a
delta-function potential. Using the time independent scattering theory, we
study how the transmission/reflection coefficients change with the height of
external potential, the incident momentum, and the strength of internal
potential. In particular, we show that the existence of internal degree of
freedom can significantly change the transmission/reflection coefficients even
without internal excitation. We consider two scenarios: the internal degree of
freedom of the incident wave is set to be in a state with even parity or odd
parity, we find that the influence of a symmetric Hamiltonian is greater on the
odd-parity internal states than on the even-parity ones.
