München 2019 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 3: Hadron Structure and Spectroscopy I
HK 3.3: Vortrag
Montag, 18. März 2019, 15:00–15:15, HS 13
Measurement of the Hadronic R Value at BESIII — •Thomas Lenz, Achim Denig, and Christoph Florian Redmer for the BESIII collaboration — Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, Deutschland
The running QED coupling constant at the Z pole αQED(MZ2) provides, alongside the anomalous magnetic moment of the muon aµ= (gµ− 2) / 2, an important precision test of the Standard Model. Their theorectical uncertainties are dominated by the hadronic vacuum polarization. Precise experimental measurements of the hadronic R value Rhad = σ(e+ e− → Hadrons) / σ(e+ e− → µ+ µ−) are used to reduce these uncertainties.
The BESIII experiment at the e+ e− collider BEPCII in Beijing has collected data at 130 different energies between 2.0 GeV and 4.6 GeV for measuring the hadronic R value with at least 105 hadronic events at each data point. This presentation gives an overview about the current status of that analysis and also discusses the feasability of using the initial state radiation technique to measure the R value in a continous spectrum.
Supported by DFG (SFB 1044).