Showing papers by "Pierpaolo Mastrolia published in 2004"
TL;DR: In this paper, the master integrals needed for the calculation of the two-loop QCD corrections to the forward-backward asymmetry of a quark-antiquark pair produced in electron-positron annihilation events were presented.
106 citations
TL;DR: In this article, the closed analytic expression of the form factors of the two-loop QED vertex amplitude for on-shell electrons of finite mass m and arbitrary momentum transfer S =−Q2 was presented.
79 citations
TL;DR: In this paper, the master integrals necessary for the analytic calculation of the box diagrams with one electron loop (NF=1) entering in the 2-loop (α3) QED virtual corrections to the Bhabha scattering amplitude of the electron are presented.
64 citations
TL;DR: In this article, the two-loop virtual, UV renormalized corrections at order α 4 (N F = 1 ) in QED to the Bhabha scattering differential cross section, for arbitrary values of the squared c.m. energy s and momentum transfer t, and on-shell electrons and positrons of finite mass m.
56 citations
TL;DR: In this article, a subset of four-loop contributions to the lowest two moments, namely those from diagrams which involve two internal loops from massive and massless fermions coupled to virtual gluons, were presented.
Abstract: The vacuum polarization due to a virtual heavy quark pair and specifically the coefficients of its Taylor expansion in the external momentum are closely related to moments of the cross section for quark-antiquark pair production in electron-positron annihilation. Relating measurement and theoretically calculated Taylor coefficients, an accurate value for charm- and bottom-quark mass can be derived, once corrections from perturbative QCD are sufficiently well under control. Up to three-loop order these have been evaluated previously. We now present a subset of four-loop contributions to the lowest two moments, namely those from diagrams which involve two internal loops from massive and massless fermions coupled to virtual gluons, hence of order alphas^3 nf^2. The calculation demonstrates the applicability of Laporta's algorithm to four-loop vacuum diagrams with both massive and massless propagators and should be considered a first step towards the full evaluation of the order alphas^3 contribution.
33 citations
TL;DR: In this paper, the authors considered the 4-loop sunrise graph with two massless lines, two lines of equal mass M and a line of mass m, for external invariant timelike and equal to m2.
18 citations
18 citations