Lattice QCD study for stringy excitation and role of UV gluons

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.