9 research outputs found
Improved Term of the Muon Anomalous Magnetic Moment
We have completed the evaluation of all mass-dependent QED
contributions to the muon , or , in two or more different
formulations. Their numerical values have been greatly improved by an extensive
computer calculation. The new value of the dominant term is 132.6823 (72), which supersedes the old value 127.50 (41).
The new value of the three-mass term
is 0.0376 (1). The term is crudely estimated to
be about 0.005 and may be ignored for now. The total QED contribution to
is , where 0.02 and
1.15 are uncertainties in the and terms and 0.85 is from
the uncertainty in measured by atom interferometry. This raises the
Standard Model prediction by , or about 1/5 of the
measurement uncertainty of . It is within the noise of current
uncertainty () in the estimated hadronic
contributions to .Comment: Appendix A has been rewritten extensively. It includes the 4th-order
calculation for illustration. Version accepted by PR
Reconsidered estimates of the 10th order QED contributions to the muon anomaly
The problem of estimating the 10th order QED corrections to the muon
anomalous magnetic moment is reconsidered. The incorporation of the recently
improved contributions to the and - corrections to
within the renormalization-group inspired scheme-invariant approach
leads to the estimate . It is in good
agreement with the estimate , obtained
by Kinoshita and Nio from the numerical calculations of 2958 10-th order
diagrams, which are considered to be more important than the still uncalculated
6122 10th-order -dependent vertex graphs, and 12672 5-loop
diagrams, responsible for the mass-independent constant contribution both to
and . This confirms Kinoshita and Nio guess about dominance of
the 10-th order diagrams calculated by them. Comparisons with other estimates
of the - contributions to , which exist in the literature,
are presented.Comment: 19 pages, LaTeX, some misprints in the text and literature corrected.
Results unchaged, to appear in Phys.Rev.
Order alpha_s^3 ln^2(1/alpha_s) Corrections to Heavy-Quarkonium Creation and Annihilation
In the framework of nonrelativistic QCD, we compute the leading
double-logarithmic corrections of order alpha_s^3 ln^2(1/alpha_s) to the
heavy-quark-antiquark bound-state wave function at the origin, which determines
the production and annihilation rates of heavy quarkonia. The phenomenological
implications for the top-antitop and Upsilon systems are discussed.Comment: 14 pages (Latex), 1 figures (Axodraw); text slightly extended, a few
typos corrected, three references added; accepted for publication in Nucl.
Phys.
Complete Result for Positronium Energy Levels at Order alpha^6 m
We have completed theoretical predictions for positronium energy levels
through order alpha^6 m by the calculation of the spin independent, radiative
recoil correction. This contribution is significant and amounts to 10.64 MHz
for the 1S state. We further perform detailed comparison of theoretical
predictions to experimental results for 1S-2S and 2S-2P transitions.Comment: 9 pages, 2 tables. Email: [email protected]
Logarithmic effects in quantum electrodynamics under low energies
Connected states (positronium, muonium, hydrogen, heavy mu-mesonic atoms) are considered in the paper aiming at the development of effective calculation methods for quantum electrodynamic corrections, containing logarithmical gain factors. As a result insertions of the vacuum polarization into multipole moments of nuclei have been calculated exactly on z_ _a_l_p_h_a_ parameter. The calculation method for logarithmic corrections in atomic systems has been suggested. The new theoretical value of the positrinium: G=7,990 (1)x10"9s"-"1 has been found; corrections relatively to alpha "4ln alpha sorder to transfer frequences in positronium have been calculatedAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio