Darmstadt 2016 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 1: Hadron Structure and Spectroscopy I
HK 1.3: Vortrag
Montag, 14. März 2016, 14:45–15:00, S1/01 A5
Measurement of the Proton Electromagnetic Form Factor in Time-like Region with the ISR Method at BESIII — •Dexu Lin1,2, Samer Ali Nasher Ahmed1,2, Alaa Dbeyssi1, Paul Larin1, Frank Maas1,2,3, Cristina Morales1, Christoph Rosner1,2, and Yadi Wang1 for the BESIII collaboration — 1Helmholtz-Institut Mainz, 55128 Mainz, Germany — 2Johann-Joachim-Becherweg 36 — 3PRISMA Cluster of Excellence, Johannes Gutenberg Universität Mainz, 55099 Mainz, Germay
The structure of the proton can be understood through the study of its electromagnetic (EM) form factors. Electron scattering experiments (space-like region) have explored the proton EM form factors with a high accuracy. Only few data on the proton form factors in the time-like region, and only a very coarse determination of the individual electric and magnetic form factors (or their ratio) has been possible so far.
The BESIII (Beijing Spectrometer III) at BEPCII (Beijing Electron Positron Collider II) has collected large data samples from J/ψ-mass up to 4.60 GeV. These data can be used to measure proton EM form factors by means of Initial-State-Radiation (ISR) events with the process e+e−→ ppγISR. With 7.408 fb−1 total luminosity of seven data samples from 3.773 -4.600 GeV, the proton form factors and the cross section of pp have been analyzed with ISR-tagged method. In this talk, the status of this work will be reported together with a discussion of the analysis of the background.