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 review of developed by the authors new techniques for covariantcalculation of matrix elements in QED, the so-called formalism of "DiagonalSpin Basis" (DSB), is presented. In DSB spin 4-vectors of in- and out- fermionsare expressed just in terms of their 4-momenta. In this approach the littleLorentz group, common for the initial and final states,is realized. This bringsthe spin operators of in- and out-particles to coincidence. The developedapproach is valid both for massive fermions and for massless ones. There occurno problems with accounting for spin flip amplitudes in it. Just 4-momenta ofparticles participating in reactions are required in it to construct themathematical apparatus for calculations of matrix elements. We apply thisformalism to the next processes: 1) M\"oller and Bhabha bremsstrahlung($e^{\pm}e^- \to e^{\pm}e^- \gamma$) in the ultrarelativistic limit wheninitial particles and photon are helicity polarized; 2) Compton back-scatteringof photons of intensive circularly polarized laser wave on a beam oflongitudinally polarized ultrarelativistic electrons ($e+n\gamma_0 \to e+\gamma$); 3) $e^+e^-$-pair production by a hard photon in simultaneous collision withseveral laser beam photons ($\gamma+n \gamma_0 \to e^+ + e^-$); 4)Bethe-Heitler process in the case of a linearly polarized photon emission by anelectron with account for proton recoil and form factors; 5) the reaction $ep\to ep \gamma$ with proton polarizability being taken into account in thekinematics when proton bremsstrahlung dominates; 6) orthopositronium 3-photonannihilation ($e^+e^{-} \to 3 \gamma$).Comment: review, 50 pages, 6 figure

The diagonal spin basis and calculation of processes involving polarized particles