相关论文: Positronium contribution to the electron g-2
We report on two recent results based on the evaluation of five-loop massless propagators in QCD and QED: (i) corrections of order $\alpha_s^4$ to the absorptive part of the polarization function in QCD with $n_f=3$;(ii) the five-loop…
In the framework of QED we evaluate the cross section for electron-positron pair production by a single photon in the presence of the external Aharonov-Bohm potential in first order of perturbation theory. We analyse energy, angular and…
We outline the recent results on the two-loop electroweak contributions to the electron-electron scattering cross sections and asymmetries. Although the two-loop corrections are strongly suppressed relative to the one-loop corrections, they…
The positronium molecule (Ps$_2$) has not been experimentally observed yet because its tiny (4.5 eV) binding energy cannot be detected when the molecule annihilates by emitting two photons with energy of 0.51 MeV each. It is shown in this…
We report a new value of electron $g-2$, or $a_e$, from 891 Feynman diagrams of order $\alpha^4$. The FORTRAN codes of 373 diagrams containing closed electron loops have been verified by at least two independent formulations. For the…
The electron structure function method is applied to calculate model-independent radiative corrections to an asymmetry of electron-proton scattering. The representations for both spin-independent and spin-dependent parts of the…
This talk summarizes the recent development in the evaluation of the leading order hadronic contributions to the running of the QED fine structure constant \alpha(s), at $s=M_{\rm Z}^2$, and to the anomalous magnetic moments of the muon…
The Modified Leading Log Approximation of QCD and the local parton hadron duality picture are shown to give a fully satisfactory description of data on charged particle energy spectra in $e^+e^-$ annihilation. The analysis of data in terms…
We perform a numerical computation of the anomalous magnetic moment ($g-2$) of the electron in QED by using the stochastic perturbation theory. Formulating QED on the lattice, we develop a method to calculate the coefficients of the…
A critical set of two-loop QED corrections to the $g$ factor of hydrogenlike ions is calculated without expansion in the nuclear binding field. These corrections are due to the polarization of the external magnetic field by the quantum…
A long-standing problem to account for the electron-positron annihilation in positron Hydrogen scattering above the Positronium formation threshold has been resolved by the use of the three-body Faddeev formalism. The multichannel…
We compute the full one-loop EW contributions of O(\alpha_S alpha_EM^3) entering the electron-positron into two b-quarks and one gluon cross section at the Z peak and LC energies. We include both factorisable and non-factorisable virtual…
We compute the full one-loop Electro-Weak (EW) contributions of O(alpha_S alpha_EM^3) entering the electron-positron into a quark-antiquark pair plus one gluon cross section at the Z peak and LC energies in presence of polarisation of the…
We calculate (g-2) of the muon and the QED coupling alpha(M_Z^2), by improving the determination of the hadronic vacuum polarization contributions and their uncertainties. We include the recently re-analysed CMD-2 data on e^+e^- -> pi^+…
We have calculated all contributions to the energy levels of parapositronium at order $m \alpha^7$ coming from vacuum polarization corrections to processes involving virtual annihilation to two photons. This work is motivated by ongoing…
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…
Recent and ongoing experimental work on the positronium spectrum motivates new efforts to calculate positronium energy levels at the level of three loop corrections. We have obtained results for one set of such corrections involving…
We present a calculation of the O(m alpha^7 ln(alpha)^2) corrections to positronium energy levels. The result is used to estimate the current uncertainty in theoretical predictions of the positronium spectrum.
In this note we present general expressions at one loop order that can be used to calculate the contributions to the anomalous magnetic moment of fundamental, charged Dirac fermions. In particular, we provide the expressions for charged and…
We calculate the two-loop contributions to the electric dipole moments of the electron and the neutron mediated by charged Higgs in a generic supersymmetric theories. The new contributions are originated from the potential CP violation in…