arXiv subjects

L. Avdeev

Publications and source records attributed to L. Avdeev.

3 recordsLinked to original sources

arXiv1997

Towards Automatic Analytic Evaluation of Diagrams with Masses

A method to calculate two-loop self-energy diagrams of the Standard Model is demonstrated. A direct physical application is the calculation of the two-loop electroweak contribution to the anomalous magnetic moment of the muon ${{1/2}(g-2)}_μ$. Presently, we confine ourselves to a ``toy'' model with only $μ$, $γ$ and a heavy neutral scalar particle (Higgs). The algorithm is implemented as a FORM-based program package. For generating and automatically evaluating any number of two-loop self-energy diagrams, a special C-program has been written. This program creates the initial FORM-expression for every diagram generated by QGRAF, executes the corresponding subroutines and sums up the final results.

hep-ph↗

arXiv1996

Towards Automatic Analytic Evaluation of Massive Feynman Diagrams

A method to calculate two-loop self-energy diagrams of the Standard Model is demonstrated. A direct physical application is the calculation of the two-loop electroweak contribution to the anomalous magnetic moment of the muon ${1/2}(g-2)_μ$. Presently we confine ourselves to a ``toy'' model with only $μ$, $γ$ and a scalar particle (Higgs). The algorithm is implemented as a package of computer programs in FORM. For generating and automatically evaluating any number of two-loop self-energy diagrams, a special C-program has been written. This program creates the initial FORM-expression for every diagram generated by QGRAF, executes the corresponding subroutines and sums up the final results.

hep-ph↗

arXiv1995

$O(αα_s^2)$ correction to the electroweak $ρ$ parameter

The three-loop QCD contributions to the vacuum polarization functions of the $Z$ and $W$ bosons at zero momentum are calculated. The top quark is considered to be massive and the other quarks massless. Using these results, we calculate the correction to the electroweak $ρ$ parameter. All computations are done in the framework of dimensional regularization as well as regularization by dimensional reduction. We use recurrence relations obtained by the method of integration by parts to reduce all integrals to a small set of master integrals. A comparison of the two-loop and three-loop QCD corrections to the $ρ$ parameter is performed.

hep-ph↗