English

QCD parameters and SM-high precision from $e^+e^-$ to Hadrons: Updated

High Energy Physics - Phenomenology 2024-04-26 v5 High Energy Physics - Experiment High Energy Physics - Lattice

Abstract

1. I update my previous comparison of the theoretical value of the muon anomaly with the new measurement and found Δaμaμexpaμth=(143±42th±22exp)×1011\Delta a_\mu\equiv a_\mu^{exp}-a_\mu^{th} = (143\pm 42_{th}\pm 22_{exp})\times 10^{-11} which is about 3σ\sigma discrepancy between the SM predictions and experiment. 2. I improve the estimate of QCD power corrections up to dimension D=12 and provide a new estimate of the ones up to D=20 within the SVZ expansion by combining the ratio of the Laplace sum rules (LSR) with the BNP τ\tau-like decay moments for the I=1 vector current. The results in Table 1 confirm a violation of the factorization of the four-quark condensates and the value of the gluon one <αsG2> <\alpha_s G^2> from some other sources. Up to D=20, I there is not any factorial nor exponential growth of the size of these power corrections. 3. I use these new values of power corrections to extract αs\alpha_s from the BNP lowest moment. To order αs4\alpha_s^4, I find within the SVZ expansion: αs(Mτ)=0.3081(50)fit(71)αs5\alpha_s(M_\tau)= 0.3081(50)_{fit}(71)_{\alpha_s^5} [resp. 0.3260(47)fit(62)αs5]0.3260 (47)_{fit}(62)_{\alpha_s^5}] implying αs(MZ)=0.1170(6)(3)evol\alpha_s(M_Z)= 0.1170(6)(3)_{evol} [resp. 0.1192(6)(3)evol0.1192(6)(3)_{evol}] for Fixed Order (FO) [resp. Contour Improved (CI)] PT series. They lead to the mean: αs(Mτ)SVZ=0.3179(58)fit(81)syst \alpha_s(M_\tau)\vert_{SVZ}=0.3179(58)_{fit}(81)_{syst} and αs(MZ)SVZ=0.1182(12)(3)evol \alpha_s(M_Z)\vert_{SVZ}= 0.1182(12)(3)_{evol} where the systematic error(syst) takes into account the discrepancy between FO and CI. Using the lowest BNP moment, we also obtain from the vector (V) component of τ\tau-decay the mean: αs(Mτ)τ,V=0.3219(52)(91)syst \alpha_s(M_\tau)\vert_{\tau,V}=0.3219(52)(91)_{syst} giving: αs(MZ)τ,V=0.1187(13)(3)evol\alpha_s(M_Z)\vert_{\tau,V}=0.1187(13)(3)_{evol}. The average of the two determinations leads to: αs(Mτ)=0.3198(72) \alpha_s(M_\tau)=0.3198(72) and αs(MZ)=0.1185(9)(3)evol\alpha_s(M_Z)= 0.1185(9)(3)_{evol}. 4. Some contributions beyond the SVZ expansion (1/Q21/Q^2, instantons and duality violation) expected to be small are discussed in Sections 10,11.

Keywords

Cite

@article{arxiv.2402.13983,
  title  = {QCD parameters and SM-high precision from $e^+e^-$ to Hadrons: Updated},
  author = {Stephan Narison},
  journal= {arXiv preprint arXiv:2402.13983},
  year   = {2024}
}

Comments

Latex sources, 19 pages, 8 figures, 3 tables. Some preliminaries results have been presented at the alphas2024 workshop (5-9th february 2024-ECT*-Trento-IT). Section 9 on the determination of alpha_s from tau-decay has been corrected. Version published in Nucl. Phys. A + Corrigendum (to appear in Nucl. Phys. A)

R2 v1 2026-06-28T14:56:01.933Z