The spectrum of closed loops of fundamental flux in D=2+1 SU(N) gauge theories

TL;DR

This paper investigates the spectrum of closed fundamental flux loops in 2+1 dimensional SU(N) gauge theories, finding that the Nambu-Goto string model accurately describes the ground state and excited states for longer strings, with deviations only at very short lengths.

Contribution

The study provides detailed numerical results for the closed-string spectrum in 2+1D SU(N) gauge theories and demonstrates the effectiveness of the Nambu-Goto model over other effective string theories.

Findings

Ground state energies match Nambu-Goto predictions for most string lengths.

Deviations from Nambu-Goto occur only at very short strings.

Nambu-Goto model outperforms other effective string theories in describing the data.

Abstract

We study the closed-string spectrum of SU(N) gauge theories in the fundamental representation in 2+1 dimensions. We calculate the energies of the lowest lying ~ 30 states using a large variety of operators characterised by the quantum numbers of parity and longitudinal momentum. We find that our results for the ground state are very well approximated by the Nambu-Goto (NG) predictions even for short strings. For the excited states, we observe significant deviations from the NG predictions only for very short strings and they decrease rapidly with increasing string length. Finally, we see that Nambu-Goto provides a much better description of our results than the effective string theoretical predictions. We discuss the continuum and large-N limits.