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Fine Structure of the QCD String Spectrum

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journal contribution
posted on 01.04.2003, 00:00 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.