Composition of the Pseudoscalar Eta and Eta' Mesons

Abstract

The composition of the eta and eta' mesons has long been a source of discussion and is of current interest with new experimental results appearing. We investigate what can be learnt from a number of different processes: V to P gamma and P to V gamma (V and P are light vector and pseudoscalar mesons respectively), P to gamma gamma, J/psi,psi' to P gamma, J/psi,psi' to P V, and chi_{c0,2} to PP. These constrain the eta-eta' mixing angle to a consistent value, phi approx 42 degrees; we find that the c cbar components are lesssim 5% in amplitude. We also find that, while the data hint at a small gluonic component in the eta', the conclusions depend sensitively on unknown form factors associated with exclusive dynamics. In addition, we predict BR(psi' to eta' gamma) approx 1 10^{-5} and BR(chi_{c0} to eta eta') approx 2 10^{-5} - 1 10^{-4}. We provide a method to test the mixing using chi_{c2} to eta eta, eta' eta', and eta eta' modes and make some general observations on chi_{c0,2} decays. We also survey the semileptonic and hadronic decays of bottom and charmed mesons and find some modes where the mixing angle can be extracted cleanly with the current experimental data, some where more data will allow this, and some where a more detailed knowledge of the different amplitudes is required.

34 pages, 11 figures. v2: version published in JHEP, added substantial section on B and D meson electroweak decays, added comment on psi' to eta(')/eta_c gamma, Figs 5 and 6 split and made clearer, added references, other minor revisions which don't change conclusions

References in corpus (13)

• Measurement of the pseudoscalar mixing angle and ${\eta }^{\prime }$ gluonium content with KLOE detector
• Gluonic contribution to $B\to {\eta }^{(\prime )}$ form factors
• Study of electromagnetic decay of $J/\psi$ and ${\psi }^{\prime }$ to vector and pseudoscalar
• Study of the $e^{+}{e}^{-}\to \eta \gamma$ process with SND detector at the VEPP-2M $e^{+}{e}^{-}$ collider
• $B\to {\eta }^{(\prime )}({\ell }^{-}{\bar{\nu }}_{\ell },{\ell }^{+}{\ell }^{-},K,K^{\ast })$ decays in the quark-flavor mixing scheme
• New Quark Relations for Hadron Masses and Magnetic Moments - A Challenge for Explanation from QCD
• Branching Ratio and CP Asymmetry of $B^0\to {\eta }^{(\prime )}{\eta }^{(\prime )}$ Decays in the Perturbative QCD Approach
• Suppression of flavor symmetry breaking in B decay sum rules
• $B^0\to \omega {\eta }^{(\prime )}$ and $\varphi {\eta }^{(\prime )}$ decays in the perturbative QCD approach
• Branching Ratio and CP Asymmetry of $B_s\to {\pi }^0{\eta }^{(\prime )}$ Decays in the perturbative QCD Approach
• Anomalous enhancement of a penguin hadronic matrix element in B->K eta'
• Measurement of charmless $B$ Decays to $\eta K^{\ast }$ and $\eta \rho$
• ${\eta }^{(\prime )}$ productions in semileptonic B decays

Cited by in corpus (10)

• Isoscalar meson spectroscopy from lattice QCD
• A global fit to determine the pseudoscalar mixing angle and the gluonium content of the eta' meson
• Re-analysis of data on a0(1450) and a0(980)
• ${\rm Y}(4S,5S)\to {\rm Y}(1S)\eta$ transitions in the rescattering model and the new BaBar measurement
• The role of $N^{\ast }(1535)$ in ${\eta }^{\prime }$ production
• eta(1405) in a chiral approach based on mixing of the pseudoscalar glueball with the first radial excitations of eta and eta'
• Understanding the radiative decays of vector charmonia to light pseudoscalar mesons
• Okubo-Zweig-Iizuka-rule violation and B\to η^{(\prime)}K branching ratios
• Eta' gluonic content and J/psi->VP decays
• Pseudoscalar mixing in J/psi and psi(2S) decay