Brower, R; Chandrasekharan, S; Negele, JW; Wiese, U-J, *QCD at fixed topology*,
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, vol. 560 no. 1-2
(2003),
pp. 64-74 [pdf], [doi] .
**Abstract:**

*Since present Monte Carlo algorithms for lattice QCD may become trapped in a fixed topological charge sector, it is important to understand the effect of calculating at fixed topology. In this Letter, we show that although the restriction to a fixed topological sector becomes irrelevant in the infinite volume limit, it gives rise to characteristic finite-size effects due to contributions from all θ-vacua. We calculate these effects and show how to extract physical results from numerical data obtained at fixed topology. © 2003 Published by Elsevier Science B.V.*