English

Leading-order hadronic contribution to the electron and muon g-2

High Energy Physics - Phenomenology 2016-06-22 v2

Abstract

I present a new data driven update of the hadronic vacuum polarization effects for the muon and the electron g2g-2. For the leading order contributions I find aμhad(1)=(686.99±4.21)[687.19±3.48]×1010a_\mu^{\mathrm{had}(1)}=(686.99\pm 4.21)[687.19\pm 3.48]\times 10^{-10} based on e+ee^+e^-data [incl. τ\tau data], aμhad(2)=(9.934±0.091)×1010a_\mu^{\mathrm{had}(2)}= (-9.934\pm 0.091) \times 10^{-10} (NLO) and aμhad(3)=(1.226±0.012)×1010a_\mu^{\mathrm{had}(3)}= (1.226\pm 0.012) \times 10^{-10} (NNLO) for the muon, and aehad(1)=(184.64±1.21)×1014a_e^{\mathrm{had}(1)}=(184.64\pm 1.21)\times 10^{-14} (LO), aehad(2)=(22.10±0.14)×1014a_e^{\mathrm{had}(2)}=(-22.10\pm 0.14)\times 10^{-14} (NLO) and aehad(3)=(2.79±0.02)×1014a_e^{\mathrm{had}(3)}=(2.79\pm 0.02)\times 10^{-14} (NNLO) for the electron. A problem with vacuum polarization undressing of cross-sections (time-like region) is addressed. I also add a comment on properly including axial mesons in the hadronic light-by-light scattering contribution. My estimate here reads aμ[a1,f1,f1](7.51±2.71)×1011.a_\mu[a_1,f_1',f_1] \sim ({ 7.51 \pm 2.71}) \times 10^{-11}\,. With these updates aμexpaμthe=(32.73±8.15)×1010a_\mu^{\rm exp}-a_\mu^{\rm the}=(32.73\pm 8.15)\times 10^{-10} a 4.0 σ\sigma deviation, while aeexpaethe=(1.10±0.82)×1012a_e^{\rm exp}-a_e^{\rm the}=(-1.10\pm 0.82)\times 10^{-12} shows no significant deviation.

Keywords

Cite

@article{arxiv.1511.04473,
  title  = {Leading-order hadronic contribution to the electron and muon g-2},
  author = {Fred Jegerlehner},
  journal= {arXiv preprint arXiv:1511.04473},
  year   = {2016}
}

Comments

10 pages, 21 figures, including updated BESIII results arXiv:1507.08188v3, results slightly go down