  In both cases of quark-antiquark (Q-Qbar) and three-quark (3Q) systems, we
study ground-state and low-lying excited-state potentials in terms of the
gluon-momentum component in the Coulomb gauge in SU(3) quenched lattice QCD. By
introducing UV-cut in the gluon-momentum space, we investigate the "UV-gluon
sensitivity" of the ground-state and excited-state potentials quantitatively.
Such a non-quark-origin excitation is a purely gluonic excitation, which can be
interpreted as a stringy excitation in the color flux-tube picture of hadrons.
For both Q-Qbar and 3Q systems, the IR part of the ground-state potential is
almost unchanged, even after cutting off high-momentum gluon component. On the
other hand, we find more significant change of excited-state potential by the
cut of UV-gluons. However, even after the removal of UV-gluons, the magnitude
of the low-lying gluonic excitation remains to be of the order of 1GeV.
