Revisiting the muon anomaly from e + e − → hadrons
Stéphan Narison · Journal of subatomic particles and cosmology. · 2025
In this talk, I revisit and present a more comprehensive and systematic estimate of the lowest order Hadronic Vacuum Polarization (HVP) contribution a μ | h v p l o to the muon anomalous magnetic moment (muon anomaly) from e + e − → Hadrons obtained recently in Ref. [1]. New CMD-3 data are used for e + e − → 2 π [2] while precise BABAR [3] and recent BELLE2 [4] e + e − → 3 π data are used to update the estimate of the I = 0 isoscalar channel below the ϕ -meson mass. Adding the data compiled by PDG22 [5] above 1 GeV and the QCD improved continuum used in Ref. [1] , one deduces : a μ | l o h v p = ( 7094 ± 37 ) × 10 − 11 . A comparison with previous data driven ( e + e − and τ -decays) estimates is done. Adding the Higher Order a μ | h v p h o corrections, the phenomenological estimate of the Hadronic Light by Light scattering up to NLO and the QED and Electroweak (EW) contributions, one obtains : Δ a μ p h e n o ≡ a μ exp − a μ p h e n o = ( 81 ± 41 ) × 10 − 11 where the recent experimental value a μ exp from Ref. [6] has been used. This result consolidates the previous one in Ref.[1], after adding the π 0 γ, ηγ contributions and can be compared with the one from the most precise Lattice result Δ a μ l a t t i c e = ( 90 ± 58 ) × 10 − 11 . Then, we deduce the (tentative) SM prediction average : Δ a μ S M = ( 87 ± 34 ) × 10 − 11 . We complete the paper by revising our predictions on the LO HVP contributions in adding the π 0 γ, ηγ contributions to the ones in Ref. [1] . Then, we obtain: a τ | l o h v p = ( 3516 ± 25 ) × 10 − 11 and Δ α h a d ( 5 ) ( M Z 2 ) = ( 2770.7 ± 4.5 ) × 10 − 5 for 5 flavours.