Correlator of heavy-quark currents at small q 2 in the large- $\beta_0$ limit

Abstract

Abstract. The correlator of vector heavy-quark currents at small q 2 is considered in the large-β0 limit. The leading IR renormalon ambiguity of the sum of the perturbative series is canceled by the UV renormalon ambiguity of the gluon condensate. Asymptotic behaviour of the perturbative series is obtained in a modelindependent way, up to a single unknown normalization factor. Gluon-virtuality distribution functions for the perturbative correction are calculated.

Small-momentum expansion of heavy-quark correlators in the large-β0 limit and αs extractions

“…The result for the small-momentum expansion of the vector correlator in the large-β 0 limit is available since the work of Grozin and Sturm [28]. Here, we confirm their result JHEP08(2021)027 and calculate, for the first time, the small-momentum expansion of the scalar, pseudoscalar, and axial-vector correlators at O(1/β 0 ).…”

Four-loop moments of the heavy quark vacuum polarization function in perturbative QCD

“…The symbol n f denotes the number of active quark-flavors, contributing through fermion-loops inserted into gluon lines. The terms being proportional to α j s n j−1 l are even known to all orders j in perturbative QCD [12]. The symbol n l denotes the number of light quarks, considered as massless.…”

Heavy-quark QCD vacuum polarisation function: analytical results at four loops

“…In the meantime, the corresponding Feynman diagrams have been calculated analytically [7,8]. The terms proportional to α , where n l in the number of light quarks, are known in all orders j of perturbative QCD [9]. References [10,11] contain the complete four-loop contributions to the first two Taylor coefficients from non-singlet diagrams.…”