Topological fluctuations and susceptibility in SU(3) lattice gauge theory

We measure the topological charge density of the (Monte Carlo generated) SU(3) vacuum. Our algorithm involves first smoothening the generated configurations in a way that conserves the total charge in the continuum limit. We work in a range of couplings 5.6 ≤ β = 6/g2 ≤ 6.0 and on lattice sizes up to 164. We find that the topological susceptibility scales like the string tension (within errors). This allows us to extract a value in physical units. Χt1/4 = 191 ± 16 MeV, in good agreement with the Witten-Veneziano mass formula. We also show how Χt is strongly suppressed as the temperature is increased through the deconfining transition, so that the UA(1) symmetry is effectively restored in the deconfined phase. Our results leave open the possibility that Χt is an order parameter for this transition. We carefully monitor finite size effects and perform a variety of calculations - reproducibility, stability under Monte Carlo, distribution of core sizes, etc. - which give us a direct insight into the approach to continuum topology. (orig.)