Bonn 2020 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 23: Hadron Structure and Spectroscopy VI
HK 23.5: Talk
Wednesday, April 1, 2020, 15:30–15:45, J-HS M
Towards a Measurement of the Hadronic R Value Using Initial State Radiation at BESIII — •Thomas Lenz, Achim Denig, and Christoph Florian Redmer for the BESIII collaboration — Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, Deutschland
The hadronic vacuum polarization is an important contribution to the running QED coupling constant at the Z pole, αQED(MZ2), and the anomalous magnetic moment of the muon aµ= (gµ− 2) / 2. Both quantities allow for crucial precision tests of the Standard Model and their theoretical uncertainties are dominated by hadronic contributions. Experimental inputs, like the hadronic R value Rhad = σ(e+ e− → hadrons) / σ(e+ e− → µ+ µ−), are used in dispersive approaches to calculate these quantities.
The large data sets collected at the BESIII experiment at the e+ e− collider BEPCII in Beijing, China, offer an excellent environment for initial state radiation (ISR) measurements. This presentation discusses the feasibility of using the ISR technique to measure Rhad in a continuous spectrum.
Supported by DFG (SFB 1044).