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

A potential explanation [U.~D.~Jentschura, Phys.\ Rev.\ A {\bf 88}, 062514(2013)] of the proton radius puzzle originating from the non-perturbativelepton-pair content of the proton is studied. Well-defined quantities thatdepend on this lepton-pair content are evaluated. Each is found to be of theorder of $10({\alpha\over \pi})^2$, so that we find such a lepton-pair contentexists in the proton. However, we argue that this relatively large result andgeneral features of loop diagrams rule out the possibility of lepton-paircontent as an explanation of the proton radius puzzle. In addition, thecontributions of a class of explanations of the proton radius puzzle (for whichthe dependence on the $\mu p$ relative distance is as a contact interaction) isdetermined.

Non-Perturbative Lepton Sea Fermions in the Nucleon and the Proton Radius Puzzle