The differential coincident pion electroproduction cross section in the 3He(e,e′π+)3H reaction has been measured with high resolution with the three-spectrometer set-up at the Mainz Microtron (MAMI) electron accelerator. Measurements were performed at the four incident energies E0 = 855, 675, 600, and 555 MeV at fixed four-momentum transfer Q2 = 0.045 GeV2, with the pions detected in parallel kinematics. This enables a separation of the measured cross section into the transverse and longitudinal structure functions by means of the Rosenbluth method. The experimental data are compared to model calculations, in which the elementary pion production amplitude includes the standard Born-amplitudes and also delta and higher resonance terms. Three-body Fadeev wave functions are used and the final state interaction of the outgoing pion is taken into account. The calculation describes the data only after medium modifications of the delta and of the pion are included.
- Coherent pion electroproduction
- Delta resonance region
- Longitudinal-transverse separation
- Medium effects
ASJC Scopus subject areas
- Nuclear and High Energy Physics