Estimation of the LO Hadronic Contribution to gμ – 2 Using the NRC KI—IHEP Total Cross Section Database

Abstract

An up-to-date compilation of the world data on the \({{e}^{ + }}{{e}^{ - }} \to {\text{hadrons}}\) total cross section is used for dispersive evaluation of the leading order hadronic contribution to the muon anomalous magnetic moment \({{a}_{\mu }} = {{({{g}_{\mu }} - 2)} \mathord{\left/ {\vphantom {{({{g}_{\mu }} - 2)} 2}} \right. \kern-0em} 2}\). An impact of the recent \(\sigma ({{e}^{ + }}{{e}^{ - }} \to {{\pi }^{ + }}{{\pi }^{ - }})\) measurement by the CMD-3 experiment being in a significant tension with comparably precisise BaBar and KLOE measurements is discussed. Our value \(a_{\mu }^{{{\text{had}}{\text{,LO}}}} = (696.2 \pm {{1.9}_{{{{e}^{ + }}{{e}^{ - }}{\text{exp}}{\text{.}}}}} \pm {{2.1}_{{{\text{syst}}{\text{.}}}}}) \times {{10}^{{ - 10}}}\) is still consistent with recent estimates by other authors made before publication of the CMD-3 result. The SM prediction of \({{a}_{\mu }}\) including our \(a_{\mu }^{{{\text{had}}{\text{,LO}}}}\) estimate \(a_{\mu }^{{{\text{SM}}}} = 11 659 184(4) \times {{10}^{{ - 10}}}\) is by \( \sim {\kern 1pt} 4.7\sigma \) lower than the experimental value \(a_{\mu }^{{{\text{exp}}}} = 11 659 205.9(2.2) \times {{10}^{{ - 10}}}\).