München 2019 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 3: Hadron Structure and Spectroscopy I
HK 3.2: Gruppenbericht
Montag, 18. März 2019, 14:30–15:00, HS 13
Measurement of the space-like transition form factor and study of direct production of χc1 at BESIII — Achim Denig, Tong Liu, •Yuping Guo, and Christoph Florian Redmer for the BESIII collaboration — Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, Mainz, Germany
The transition form factors (TFF) of mesons are important experimental inputs to the calculation of the hadronic light-by-light (HLbL) contribution of muon anomaly, aµ. The HLbL contribution is one of the two limitations of the accuracy of the theoretical calculation. The TFFs can be measured in space-like regime through two-photon process at e+e− collision machine, such as BESIII. The advantage of the measurement at BESIII is that the working center-of-mass (CM) energy allows measurement of the TFF in relative low Q2 region, which is the relevant kinematic region for the calculation. The measurements of the TFF of π0 as a function of Q2 from 0.3 to 3.0 GeV2 and the amplitude of π+π− with Q2 from 0.1 to 4.0 GeV2 will be presented.
In gamma-gamma interactions, a direct production of non-vector resonances becomes possible at e+e− accelerators. Currently, only the direct production of vector meson with JPC=1– has been observed, mesons with other quantum numbers are produced through the decays of the vector mesons. With a dedicated set of four data samples collected at CM energies around the χc1 mass, the direct production of χc1 in e+e− machine has been studied. The status of the analysis will be presented.