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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The difference in proton radii measured with $\mu p$ atoms and with $ep$atoms and scattering remains an unexplained puzzle. The PSI MUSE proposal is tomeasure $\mu p$ and $e p$ scattering in the same experiment at the same time.The experiment will determine cross sections, two-photon effects, form factors,and radii independently for the two reactions, and will allow $\mu p$ and $ep$results to be compared with reduced systematic uncertainties. These data shouldprovide the best test of lepton universality in a scattering experiment todate, about an order of magnitude improvement over previous tests. Measuringscattering with both particle polarities will allow a test of two-photonexchange at the sub-percent level, about a factor of four improvement onuncertainties and over an order of magnitude more data points than previous lowmomentum transfer determinations, and similar to the current generation ofhigher momentum transfer electron experiments. The experiment has the potentialto demonstrate whether the $\mu p$ and $ep$ interactions are consistent ordifferent, and whether any difference results from novel physics or two-photonexchange. The uncertainties are such that if the discrepancy is real it shouldbe confirmed with $\approx$5$\sigma$ significance, similar to that alreadyestablished between the regular and muonic hydrogen Lamb shift.

Technical Design Report for the Paul Scherrer Institute Experiment R-12-01.1: Studying the Proton "Radius" Puzzle with {\mu}p Elastic Scattering