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

Muonic helium atom hyperfine structure (HFS) measurements are a sensitivetool to test the three-body atomic system and bound-state quantumelectrodynamics theory, and determine fundamental constants of the negativemuon magnetic moment and mass. The world's most intense pulsed negative muonbeam at the Muon Science Facility of the Japan Proton Accelerator ResearchComplex allows improvement of previous measurements and testing further $CPT$invariance by comparing the magnetic moments and masses of positive andnegative muons (second-generation leptons). We report new ground-state HFSmeasurements of muonic helium-4 atoms at a near-zero magnetic field, performedfor the first time using a small admixture of CH$_{4}$ as an electron donor toform neutral muonic helium atoms efficiently. Our analysis gives $\Delta\nu$ =4464.980(20) MHz (4.5 ppm), which is more precise than both previousmeasurements at weak and high fields. The muonium ground-state HFS was alsomeasured under the same conditions to investigate the isotopic effect on thefrequency shift due to the gas density dependence in He with CH$_{4}$ admixtureand compared with previous studies. Muonium and muonic helium can be regardedas light and heavy hydrogen isotopes with an isotopic mass ratio of 36. Noisotopic effect was observed within the current experimental precision.

Improved Measurements of Muonic Helium Ground-State Hyperfine Structure at a Near-Zero Magnetic Field