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arXiv · hep-lat/0211035

QCD and the eta prime Mass: Instantons or Confinement?

Thomas Schaefer
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Abstract

We argue that lattice calculations of the $η'$ mass in QCD with $N_c=2$ colors performed at non-zero baryon chemical potential can be used to study the mechanism responsible for the mass of the $η'$. QCD with two colors is an ideal laboratory because it exhibits confinement, chiral symmetry breaking and a would-be $U(1)_A$ Goldstone boson at all densities. Since the instanton density and the confinement scale vary with density in a very different way, instantons are clearly distinguishable from other possible mechanisms. There is an instanton prediction for the $η'$ mass at large density that can be compared to lattice results. The density dependence of the instanton contribution is a simple consequence of the integer topological charge carried by the instanton. We also argue that $N_c=3$ color QCD at finite isospin density can be used in order to study the origin of OZI-violation in the scalar sector.

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Thomas Schaefer. 2002-11-21. QCD and the eta prime Mass: Instantons or Confinement?. https://doi.org/10.1103/physrevd.67.074502

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