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

With the help of the Mellin-Barnes transform, we show how to simultaneouslyresum the expansion of a heavy-quark correlator around q^2=0 (low-energy), q^2=4 m^2 (threshold, where m is the quark mass) and q^2=-\infty (high-energy) in asystematic way. We exemplify the method for the perturbative vector correlatorat O(alpha_s^2) and O(alpha_s^3). We show that the coefficients, Omega(n), ofthe Taylor expansion of the vacuum polarization function in terms of theconformal variable \omega admit, for large n, an expansion in powers of 1/n (upto logarithms of n) that we can calculate exactly. This large-n expansion has asign-alternating component given by the logarithms of the OPE, and a fixed-signcomponent given by the logarithms of the threshold expansion in the externalmomentum q^2.Comment: 27 pages, 8 figures. We fix typos in Eqs. (18), (27), (55) and (56).  Results unchange

Resummation of threshold, low- and high-energy expansions for heavy-quark correlators