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 Plus

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

Zendy Tools

Zendy Open

Within the ghost-free Analytic Perturbation Theory (APT), devised in the lastdecade for low energy QCD, simple approximations are proposed for 3-loopanalytic couplings and their effective powers, in both the space-like(Euclidean) and time-like (Minkowskian) regions, accurate enough in the largerange (1--100 GeV) of current physical interest.\par Effectiveness of the newModel is illustrated by the example of $\Upsilon(1\mathrm{S})$ decay where thestandard analysis gives $\alpha_s(M_{\Upsilon})=0.170\pm 0.004$ value that isinconsistent with the bulk of data for $\alpha_s$.  Instead, we obtain $\alpha_s^{Mod}(M_{\Upsilon})=0.185\pm 0.005$ thatcorresponds to $\alpha_s^{Mod}(M_Z)=0.120\pm 0.002 $ that is close to the worldaverage.\par The issue of scale uncertainty for $\Upsilon$ decay is alsodiscussed.Comment: 12 pages, 0 figures. Model slightly modified to increase its  accuracy. Numerical results upgraded, references added. The issue of scale  uncertainty is discusse

Analytic perturbation theory for QCD practitioners and upsilon decay