English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The value of the $\eta - \eta'$ mixing angle $\theta_P$ is phenomenologicallydeduced from a rather exhaustive and up-to-date analysis of data includingstrong decays of tensor and higher-spin mesons, electromagnetic decays ofvector and pseudoscalar mesons, $J/\psi$ decays into a vector and apseudoscalar meson, and other transitions. A value of $\theta_P$ between$-17^\circ$ and $-13^\circ$ is consistent with all the present experimentalevidence and the average $\theta_P=-15.5^\circ\pm 1.3^\circ$ seems to befavoured.Comment: 17 pages, LaTeX. 2 references added, some comments on Chiral  Perturbation Theor

The $\eta$ - $\eta\prime$ mixing angle revisited