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

Positronium is an ideal system for the research of the bound state QED. Thehyperfine splitting of positronium (Ps-HFS: about 203 GHz) is sensitive to newphysics beyond the Standard Model via a vacuum oscillation between an ortho-Psand a virtual photon. Previous experimental results of the Ps-HFS show 3.9sigma(15 ppm) discrepancy from the QED calculation. All previous experimentsused an indirect method with static magnetic field to cause Zeeman splitting (afew GHz) between triplet states of ortho-Ps, from which the HFS value wasderived. One possible systematic error source of the indirect method is thestatic magnetic field. We are developing a new direct measurement system of thePs-HFS without static magnetic field. In this measurement we use a gyrotron, anovel sub-THz light source, with a high-Finesse Fabry-Perot cavity to obtainenough radiation power at 203 GHz. The present status of the optimizationstudies and current design of the experiment are described.

Probing the Energy Structure of Positronium with a 203 GHz Fabry-Perot Cavity