22 research outputs found

    Tenth-Order QED Contribution to the Electron g-2 and an Improved Value of the Fine Structure Constant

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    This paper presents the complete QED contribution to the electron g-2 up to the tenth order. With the help of the automatic code generator, we have evaluated all 12672 diagrams of the tenth-order diagrams and obtained 9.16 (58)(\alpha/\pi)^5. We have also improved the eighth-order contribution obtaining -1.9097(20)(\alpha/\pi)^4, which includes the mass-dependent contributions. These results lead to a_e(theory)=1 159 652 181.78 (77) \times 10^{-12}. The improved value of the fine-structure constant \alpha^{-1} = 137.035 999 174 (35) [0.25 ppb] is also derived from the theory and measurement of a_e.Comment: 4 pages, 2 figures. Some numbers are slightly change

    Everyone Makes Mistakes - Including Feynman

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    This talk is dedicated to Alberto Sirlin in celebration of his seventieth birthday. I wish to convey my deep appreciation of his many important contributions to particle physics over 40 years and look forward to many more years of productive research.Comment: 16 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

    Improved α4\alpha^4 Term of the Muon Anomalous Magnetic Moment

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    We have completed the evaluation of all mass-dependent α4\alpha^4 QED contributions to the muon g2g-2, or aμa_\mu, in two or more different formulations. Their numerical values have been greatly improved by an extensive computer calculation. The new value of the dominant α4\alpha^4 term A2(8)(mμ/me)A_2^{(8)} (m_\mu / m_e) is 132.6823 (72), which supersedes the old value 127.50 (41). The new value of the three-mass term A3(8)(mμ/me,mμ/mτ)A_3^{(8)} (m_\mu / m_e, m_\mu / m_\tau) is 0.0376 (1). The term A2(8)(mμ/mτ)A_2^{(8)} (m_\mu / m_\tau) is crudely estimated to be about 0.005 and may be ignored for now. The total QED contribution to aμa_\mu is 116584719.58(0.02)(1.15)(0.85)×1011116 584 719.58 (0.02)(1.15)(0.85) \times 10^{-11}, where 0.02 and 1.15 are uncertainties in the α4\alpha^4 and α5\alpha^5 terms and 0.85 is from the uncertainty in α\alpha measured by atom interferometry. This raises the Standard Model prediction by 13.9×101113.9 \times 10^{-11}, or about 1/5 of the measurement uncertainty of aμa_\mu. It is within the noise of current uncertainty (100×1011\sim 100 \times 10^{-11}) in the estimated hadronic contributions to aμa_\mu.Comment: Appendix A has been rewritten extensively. It includes the 4th-order calculation for illustration. Version accepted by PR
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