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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We compute in order alpha_s the nonrelativistic QCD (NRQCD) short-distancecoefficients that match quark-antiquark operators of all orders in theheavy-quark velocity v to the electromagnetic current. We employ a new methodto compute the one-loop NRQCD contribution to the matching condition. The newmethod uses full-QCD expressions as a starting point to obtain the NRQCDcontribution, thus greatly streamlining the calculation. Our results show that,under a mild constraint on the NRQCD operator matrix elements, the NRQCDvelocity expansion for the quark-antiquark-operator contributions to theelectromagnetic current converges. The velocity expansion converges rapidly forapproximate J/psi operator matrix elements.

Order-alpha_s corrections to the quarkonium electromagnetic current at all orders in the heavy-quark velocity