Severo Ochoa Seminar: Properties of the eta and eta-prime mesons

por Sara Collins (Regensburg University)

martes 5 nov. 2019 12:00 → 13:00 Europe/Madrid

Seminar Room, 1.1.1 (IFIC)

The eta and eta-prime mesons have been the focus of many theoretical studies because of their connection to the chiral anomaly of QCD and their important role in many QCD processes.  In the past, lattice studies have largely been restricted to determining their masses due to the computational challenge of evaluating the quark line disconnected diagrams, with the systematics of the calculations often not being explored. Recent technical developments now mean matrix elements relevant for decay form factors and decay constants can be
determined too. I will present results for the four (independent) axial decay constants of the eta and eta-prime mesons, in addition to their masses. The analysis is performed on the CLS 2+1 flavour ensembles, with pion masses ranging from 420 MeV down to the physical mass point. Four lattice spacings and two distinct approaches to the physical point in the quark mass plane enable the continuum limit and chiral interpolation to be performed with care. Results are obtained for some of the lesser known low energy constants that appear in NLO large-NcChPT expressions. As a by-product, we test the flavour-singlet PCAC relation, probing the purely gluonic contribution to the singlet decay constants.