Related papers: Two-Loop Correction to Bhabha Scattering
A critical subject in fully differential QED calculations originates from numerical instabilities due to small fermion masses that act as regulators of collinear singularities. At next-to-next-to-leading order (NNLO) a major challenge is…
We present the results of our calculations to a one, two, and three loop approximation of the e$^+$e$^-$$\rightarrow$e$^+$e$^-$ Bhabha scattering cross-section at small angles. All terms contributing to the radiatively corrected…
We present a detailed analysis of QED corrections to $\bar{B} \to \bar{K} \ell^+ \ell^-$ decays at the double-differential level. Cancellations of soft and collinear divergences are demonstrated analytically using the phase space slicing…
We discuss the computation of QCD virtual corrections to the top production and decay process at linear colliders. The double pole approximation (DPA) is used, and we comment on similarities and differences between our results and results…
In the supersymmetric extension of the Standard Model we derive the two-loop QCD corrections to the scalar quark contributions to the electroweak precision observables entering via the rho parameter. A very compact expression is derived for…
We define a complete set of scalar master integrals (MIs) for massive 2-loop QED Bhabha scattering. Among others, there are thirty three 2-loop box type MIs. Five of them have been published in (semi-)analytical form, one is determined…
We clarify a discrepancy between two previous calculations of the two-loop QED Euler-Heisenberg Lagrangian, both performed in proper-time regularization, by calculating this quantity in dimensional regularization.
I discuss an application of numerical techniques for massive two-loop Feynman diagram evaluation to a phenomenologically very important rare decay process, B -> X_s l+l-. This process, currently being measured at B factories, has been…
We consider the two-loop corrections to the $HW^+W^-$ vertex at order $\alpha\alpha_s$. We construct a canonical basis for the two-loop integrals using the Baikov representation and the intersection theory. By solving the $\epsilon$-form…
A new Monte Carlo event generator for wide angle Bhabha scattering and muon pair production in $e^+e^-$ collisions is described. The program includes complete one-loop electroweak corrections, and QED radiative corrections. The O($\alpha$)…
We study the renormalization of the QCD $\theta$ angle at the two-loop level focusing on divergent and finite $CP$-violating contributions from evanescent operators, using dimensional regularization with the BMHV scheme. When one considers…
QCD one-loop corrections to the semileptonic process $e^+ e^- \to \mu^- \bar \nu_\mu u \bar d$ are computed. We compare the exact calculation with a ``naive'' approach to strong radiative corrections which has been widely used in the…
We derive logarithmically enhanced two-loop virtual electroweak corrections for arbitrary fermion-scattering processes at the TeV scale. This extends results previously obtained for massless fermion scattering to processes that involve also…
Analitical calculations have been used to describe the calorimeter event selection in small-angle electron-positron scattering at LEP1. The first-order QED correction to the Born cross-section has been derived with leading log and the…
We report on a high-precision calculation of the Bhabha process in QED, of interest for precise luminosity determination of low-energy electron-positron colliders. The calculation is based on the matching of exact next-to-leading order…
We report on two recent multiloop results in QED: (i) the four-loop corrections to the conversion relations between the QED charge renormalized in the on-shell and MS-bar schemes; (ii) analytical evaluation of a class of asymptotic…
We study electron-electron contact-interaction searches in the process e+ + e- --> e+ + e- at a future linear collider with longitudinally polarized beams, and evaluate the model-independent constraints on the contact interaction…
With the advent of generalized unitarity and parametric integration techniques, the construction of a generic Next-to-Leading Order Monte Carlo becomes feasible. Such a generator will entail the treatment of QCD color in the amplitudes. We…
We present the Monte Carlo program BHAGEN95, for calculating the cross-section of the Bhabha scattering process at LEP1/SLC and LEP2 energies, usable with continuity from small to large-angle configurations. We discuss some improvements in…
The leptonic QED radiative corrections are calculated in the next-to-leading log approximation ${\cal O}[\alpha^2 \ln(Q^2/m_e^2)]$ for unpolarized deeply inelastic $ep$--scattering in the case of mixed variables. The corrections are…