Related papers: Some O(\alpha^2) Annihilation Type Contributions t…
Order alpha^2 contribution to the orthopositronium decay rate due to one-photon virtual annihilation is found to be delta Gamma = (alpha/pi)^2 (pi^2 ln(alpha) - 0.8622(9))Gamma_LO.
I consider the problem of the evaluation of the orthopositronium decay rate, including second order radiative corrections. I present a brief theoretical discussion of this problem and a review of the results available in literature, and,…
The matrix element for the decay of orthopositronium to three photons can be expressed in terms of three independent amplitudes. We describe the analytic evaluation of these amplitudes, both to lowest order and with the inclusion of all…
A closed analytic expression is given for the spectrum of low energy photons in the annihilation of orthopositronium, which expression sums all the effects of the Coulomb interaction between the electron and the positron. The applicability…
We present a new, simplified analysis of the low-energy electron-positron interaction, and use the resulting effective theory to calculate the binding effects that contribute to the decay rate, Gamma, of orthopositronium, through…
Corrections $\sim \alpha^2 $ to the positronium decay rate, induced by one--loop vacuum polarization diagram, are calculated. Their relative values are $0.4468(3)(\alpha/\pi)^2$ for para- and $0.960(3)(\alpha/\pi)^2$ for orthopositronium.
We discuss how contributions to the order ${\cal O} (m \alpha^8)$ orthopositronium decay rate can be separated into two categories, one due to relativistic momenta and calculable in terms of QED scattering amplitudes, the other due to low…
We present the O(alpha) and O(alpha^3 ln(alpha)) corrections to the total decay width of orthopositronium in closed analytic form, in terms of basic transcendental numbers, which can be evaluated numerically to arbitrary precision.
The order - \alpha radiative corrections to the differential decay rate of polarized orthopositronium are obtained. Their influences on the three photons coincidence rate as a function of positronium polarization is considered.
The logarithmically enhanced alpha^3 ln(1/alpha) corrections to the para- and orthopositronium decay widths are calculated in the framework of dimensionally regularized nonrelativistic quantum electrodynamics.In the case of parapositronium,…
We evaluate the O(alpha_em/alpha_s) correction to the rate of B -> X_s gamma decay, i.e. we resum all the 0[ alpha_em ln M_W^2/m_b^2 x (alpha_s ln M_W^2/m_b^2)^n ] corrections for n=0,1,2,... Our calculation differs from the previously…
The partial decay rate $\Gamma(Z\to b\bar{b})$ is significantly influenced by the mass of the top quark due to electroweak radiative corrections. The leading $\sim m_t^2$ and the next-to-leading contribution $\sim \ln m_t^2$ are known to be…
Two-loop QED corrections to the decay rate of parapositronium (p-Ps) into two photons are presented. We find Gamma(p-Ps --> 2 photons) = 7989.64(2)/microsec. The non-logarithmic O(alpha^2) corrections turn out to be small, contrary to some…
In this talk we consider the O(alpha_s) radiative corrections to the decay of an unpolarized top quark into a bottom quark and a W gauge boson where the helicities of the W are specified as transverse-plus, transverse-minus and…
Order \alpha^2 corrections to the decay rate of orthopositronium are calculated in the framework of nonrelativistic QED. The resulting contribution is found to be in significant disagreement with one set of experimental measurements though…
Positronium annihilation amplitudes that are computed by assuming a factorization approximation with on-shell intermediate leptons do not exhibit good analytical behaviour. Using dispersion techniques, we find new contributions that…
Self-energy corrections of order O(alpha^2) to the parapositronium and orthopositronium decay rates are calculated. Numerical values of the corresponding coefficients are B_p=-3.74, B_o=2.02.
The photon spectrum in orthopositronium to 3 gamma decay is computed using effective field theory methods. For energetic photons, the spectrum agrees with the Ore-Powell result, but deviates from it when the photon energy is comparable to…
Positronium annihilation amplitudes that are computed by assuming a factorization approximation with on-shell intermediate leptons, do not exhibit good analytical behavior. We propose an ansatz which allows to include binding energy…
Order $\alpha^2$ corrections to the decay rate of parapositronium are calculated. A QED scattering calculation of the amplitude for electron-positron annihilation into two photons at threshold is combined with the technique of effective…