Form Factor Measurements at BESIII for an Improved Standard Model Prediction of the Muon g-2

Marco Destefanis

doi:10.1142/s2010194518600261

Abstract

The anomalous part of the magnetic moment of the muon, (g-2)[Formula: see text], allows for one of the most precise tests of the Standard Model of particle physics. We report on recent results by the BESIII Collaboration of exclusive hadronic cross section channels, such as the 2[Formula: see text], 3[Formula: see text], and 4[Formula: see text] final states. These measurements are of utmost importance for an improved calculation of the hadronic vacuum polarization contribution of (g-2)[Formula: see text], which currenty is limiting the overall Standard Model prediction of this quantity. BESIII has furthermore also intiatated a programme of spacelike transition form factor measurements, which can be used for a determination of the hadronic light-by-light contribution of (g-2)[Formula: see text] in a data-driven approach. These results are of relevance in view of the new and direct measurements of (g-2)[Formula: see text] as foreseen at Fermilab/USA and J-PARC/Japan.

Highlights

The muon anomalous part of the magnetic moment (MAMM) is one of the most interesting topics which could be addressed in modern experiments
According to the Dirac theory, the gyromagnetic ratio can be defined as g = 2(1 + a), where a is the MAMM, that, in the case of the muon, is aμ gμ −2 2
The measured cross sections could be used as input in the calculation of the muon anomalous magnetic moment contribution coming from three pions final states

Summary

Anomalous Magnetic Moment of the Muon

The muon anomalous part of the magnetic moment (MAMM) is one of the most interesting topics which could be addressed in modern experiments. The muon anomaly arises mainly from quantum fluctuation, but in order to provide a precision measurement, the weak and the. This is an Open Access article published by World Scientific Publishing Company. The fact that the dispersion integral is proportional to 1/s2 suggests that the main contribution to the HVP comes from the low mass region In particular it depends on pionic events, especially from the 2π final state. The BESIII experiment is able to provide a high precision measurement of the pionic contributions, offering a wider mass range and a lower suppression of ISR events, which is connected with the radiator function of the dispersion integral

BEPCII and BESIII Spectrometer

Findings

Conclusions