Time-like proton form factor measurement with P(-)ANDA
The electromagnetic probe is an excellent tool to investigate the structure of the nucleon. The nearly 4π detector PANDA, will allow to make a precise determination of the electromagnetic form factors of the proton in the time-like region with unprecedented precision. In the one-photon exchange approximation, the center of mass unpolarized differential cross section of the reaction pp → e~+e~- is a linear combination of the squared moduli of the electric G_E and magnetic G_M proton form factors. The precise measurement of the angular distribution over almost full angular range then directly gives these quantities. At present only two experiments have provided the ratio R=|G_E|/|G_M| but with large statistical uncertainties. It is shown that with strict PID cuts and a kinematic fit, the dominant background, (p)p→π~+π~-, can be supressed to much less than 1% of the signal, without affecting the extraction of the ratio R. PANDA will therefore offer a unique opportunity to measure the ratio with a precision ranging from<1% at low q~2 up to 30 % for q~2 =14 (GeV/c)~2.
electromagnetic form factors nuclear structure FAIR PANDA
M.Sudot
Institut de Physique Nucleaire,CNRS/IN2P3,Universite Paris Sud,Orsay,France
国际会议
The 12th International Workshop on the Physics of Ezcited Nucleon NSTAR2009(2009激发态核子物理研讨会)
北京
英文
1244-1248
2009-04-19（万方平台首次上网日期，不代表论文的发表时间）