Related papers: Multiloop Calculations: towards R at Order alpha_s…
We present the first genuine QCD five-loop calculation of the vacuum polarization functions: analytical terms of order alpha_s^4 n_f^2 to the absorptive parts of vector and scalar correlators. These corrections form an important…
The calculation of the R-ratio of electron-positron annihilation into hadrons is discussed. The method, which enables one to properly account for all the effects due to continuation of the spacelike perturbative results into the timelike…
We provide a brief summary of recent developments in QCD calculations in and beyond fixed-order perturbation theory, for observables in $e^{+}e^{-}$ annihilation as well as hadron collisions.
We present a calculation of the differential two jet cross section in e^+e^- annihilation through next-to-next-to-leading order in the strong coupling constant alpha_s. The calculation is performed using a new method for dealing with real…
Using modern multiloop calculation methods, we derive the analytical expressions for the total cross sections of the processes $e^-\gamma \to e^-X\bar{X}$ with $X=\mu,\,\gamma$ or $e$ at arbitrary energies. For the first two processes our…
We use a recent O(alpha_s^2) calculation of the differential cross section for the production of heavy quarks in e+e- annihilation to compute a few moments of the heavy quark single-inclusive production cross section. We verify that,…
The total cross section for electron-positron annihilation into hadrons is calculated in the region just below the B meson threshold. QCD corrections up to third order, quark mass effects, initial state radiation, the running of alpha_QED…
We present the first explicit formulae for the complete set of one-loop helicity amplitudes necessary for computing next-to-leading order corrections for e^+ e^- annihilation into four jets, for W, Z or Drell-Yan production in association…
We consider the computation of D and B fragmentation functions in e+e- annihilation. We compare the results of fitting present data using the next-to-leading-logarithmic resummed approach, versus the O(alpha_s^2) fixed-order calculation,…
Total hadron multiplicities and multiplicities of hadrons in events with heavy quarks in $e^+e^-$ annihilation at the energies of LEP-1.5 and LEP-2 are calculated on the basis of QCD.
We report on our calculation of the order \alpha_s^4 axial singlet contributions for the decay rates of the Z-boson as well as the vector singlet contribution to the cross section for electron-positron annihilation into hadrons. Together…
We apply the modern multiloop methods to the calculation of the total cross sections of electron-positron annihilation to 2 and 3 photons exactly in $s/m^2$ with the accuracy $O(\alpha^3)$. Examining the asymptotics of our results, we find…
A general method for calculating \NLO cross sections in perturbative QCD is presented. The algorithm is worked out for calculating $N$-jet cross sections in hadron-hadron collisions. The generalization of the scheme to performing…
We present the higher order QCD corrections to the fragmentation functions and the corresponding cross sections.
We compute the order alpha_s^2 corrections to the one particle inclusive electroproduction cross section of hadrons with non vanishing transverse momentum. We perform the full calculation analytically, and obtain the expression of the…
The top quark cross section close to threshold in $e^+e^-$ annihilation is computed including the summation of logarithms of the velocity at next-to-next-to-leading-logarithmic order in QCD. The remaining theoretical uncertainty in the…
We calculate the rate for $e^+e^-$ annihilation into four jets at next-to-leading order in perturbative QCD, but omitting terms that are suppressed by one or more powers of $1/\Nc^2$, where $\Nc$ is the number of colors. The…
We evaluate the multiplicity of hadrons in the $e^+e^-$-annihilation at a given thrust $T$ in the modified leading-log approximation, including $O(\sqrt{\alpha_s})$ corrections. The calculation is done at a large value of $\tau =1-T$ by the…
An analytic formula is given for the total scattering cross section of an electron and a photon at order $\alpha^3$. This includes both the double-Compton scattering real-emission contribution as well as the virtual Compton scattering part.…
We report on the next-to-leading order QCD calculation for e+ e- --> 4 jets. We explain some modern techniques which have been used to calculate the one-loop amplitudes efficiently. We further report on the general purpose numerical program…