\eta - \eta' Mixing -- From Electromagnetic Transitions to Weak Decays of Charm and Beauty Hadrons (presented at Hadron 2011)

TL;DR

Understanding the e9 and e9' wave functions in terms of quark and gluon components is crucial for probing non-perturbative QCD and interpreting meson decay processes, with implications for new physics searches.

Contribution

The paper highlights the importance of specific measurements to better determine e9 and e9' wave functions, aiding in disentangling decay subprocesses and CP asymmetries.

Findings

Current data does not provide a clear picture of e9 and e9' wave functions.

Identifies key measurements needed to improve understanding of these wave functions.

Enhanced knowledge will clarify decay subprocess contributions and CP asymmetries in meson decays.

Abstract

It has been realized for a long time that knowing the \eta and \eta' wave functions in terms of quark and gluon components probes our understanding of non-perturbative QCD dynamics. Great effort has been given to this challenge -- yet no clear picture has emerged even with the most recent KLOE data. We point out which measurements would be most helpful in arriving at a more definite conclusion. A better knowledge of these wave functions will significantly help to disentangle the weight of different decay subprocesses in semi-leptonic decays of D^+, D_s^+ and B^+ mesons. The resulting insights will be instrumental in treating even non-leptonic B transitions involving $\eta$ and $\eta^{\prime}$ and their CP asymmetries; thus they can sharpen the case for or against New Physics intervening there.