Orateur
Dr
David GREYNAT
(Fisica Teorica - Uni. de Zaragoza)
Description
With the help of the Mellin-Barnes transform, we show how to simultaneously resum the expansion of any kind of non-analytic functions around 0, 1 and $ infinity$ in a systematic way. We exemplify the method for the perturbative vector, axial scalar and pseudo-scalar correlator at $\mathcal{O}(\alpha_s^{3})$. We show that the coefficients, $\Omega(n)$, of the Taylor expansion of the vacuum polarization function in terms of the conformal variable $\omega$ admit, for large $n$, an expansion in powers of $1/n$ (up to logarithms of $n$) that we can calculate exactly. This large-$n$ expansion has a sign-alternating component given by the logarithms of the OPE, and a fixed-sign component given by the logarithms of the threshold expansion in the external momentum $q^2$.
Auteur principal
Dr
David GREYNAT
(Fisica Teorica - Uni. de Zaragoza)
Co-auteurs
Dr
Pere Masjuan
(Universidad de Granada)
Prof.
Santiago PERIS
(IFAE- Barcelona)
