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/

Zendy Open

Presents the pdf analysis as premium feature

PDF Analysis

Insights

Presents the summarisation as premium feature

Summarisation

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

The notion of position operator for massless spinning particles is discussedin some detail. The noncommutativity of coordinates is related to the gaugesymmetry following from the freedom in definition of standard state in Wigner'sconstruction of induced representations of Poincare group. The counterpart ofNewton-Wigner operator is discussed. It is explained why the Newton-Wignerconstruction works only for helicity $ \mid\lambda\mid\leq1/2$.

Localizability, gauge symmetry and Newton-Wigner operator for massless particles