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Fine Structure of the QCD String Spectrum

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journal contribution
posted on 01.04.2003 by Keisuke Jimmy Juge, Julius Kuti, Colin Morningstar

Using advanced lattice methods in quantum chromodynamics, three distinct scales are established in the excitation spectrum of the gluon field around a static quark-antiquark pair as the color source separation R is varied. On the shortest length scale, the excitations are consistent with states created by local gluon field operators arising from a multipole operator product expansion. An intermediate crossover region below 2 fm is identified with a dramatic rearrangement of the level orderings. On the largest length scale of 2–3 fm, the spectrum agrees with that expected for stringlike excitations. The energies nearly reproduce asymptotic π/R string gaps, but exhibit a fine structure, providing important clues for developing an effective bosonic string description.