  Studying the Witten-Sakai-Sugimoto model with type IIA string theory, we find
the glueball-baryon interaction is predicted in this model. The glueball is
identified as the 11D gravitational waves or graviton described by the M5-brane
supergravity solution. Employing the relation of M-theory and type IIA string
theory, glueball is also 10D gravitational perturbations which are the excited
modes by close strings in the bulk of this model. On the other hand, baryon is
identified as a D4-brane wrapped on $S^{4}$ which is named as baryon vertex, so
the glueball-baryon interaction is nothing but the close string/baryon vertex
interaction in this model. Since the baryon vertex could be equivalently
treated as the instanton configurations on the flavor brane, we identify the
glueball-baryon interaction as "graviton-instanton" interaction in order to
describe it quantitatively by the quantum mechanical system for the collective
modes of baryons. So the effective Hamiltonian can be obtained by considering
the gravitational perturbations in the flavor brane action. With this
Hamiltonian, the amplitudes and the selection rules of the glueball-baryon
interaction can be analytically calculated in the strong coupling limit. We
show our calculations explicitly in two characteristic situations which are
"scalar and tensor glueball interacting with baryons". Although there is a long
way to go, our work provides a holographic way to understand the interactions
of baryons in hadronic physics and nuclear physics by the underlying string
theory.
