Electromagnetic Form Factors in the Time Like Domain

The electromagnetic form factors in the time like domain can be accessed by the reaction or its time inversed process. Despite a long standing experimental effort to determine these form factors, the precision in the knowledge of the ratio |GE|/|GM| ist still very poor in the time like domain. All world data suffer from limited statistics and therefore have used the hypothesis of |GE|=|GM| in order to extract a value for |GM|. While there is no theory argument for this hypothesis, recent JLAB data from polarisation transfer in elastic electron scattering show, that this hypothesis does not hold. Only a few data points allow the determination of |GE|/|GM| with large uncertainties, the different experiments show considerable differences. The P̄ANDA-experiment at the future GIS/FAIR accelerator complex will offer the possibility to measure the modulus of these form factors with unprecedented accuracy.