$\eta$ and ${\eta }^{\prime }$ masses and decay constants

Abstract

We present preliminary results for the masses and decay constants of the $\eta$ and ${\eta }^{\prime }$ mesons using CLS $N_f=2+1$ ensembles. One of the major challenges in these calculations are the large statistical fluctuations due to disconnected quark loops. We tackle these by employing a combination of noise reduction techniques which are tuned to minimize the statistical error at a fixed cost. On the analysis side we carefully assess excited states contributions by using a direct fit approach.

Comments: 8 pages, 7 figures, talk presented at the 35th International Symposium on Lattice Field Theory, 18-24 June 2017, Granada, Spain. v2: corrected axis label