Abstract
In a kinematically complete experiment at the Mainz microtron MAMI, pion angular distributions of the 3He(e,e′π+)3H reaction have been measured in the excitation region of the Δ resonance to determine the longitudinal (L), transverse (T), and the LT interference part of the differential cross section. The data are described only after introducing self-energy modifications of the pion and Δ-isobar propagators. Using Chiral Perturbation Theory (ChPT) to extrapolate the pion self energy as inferred from the measurement on the mass shell, we deduce a reduction of the π+ mass of Δmπ+ = (-1.7-2.1+1.7) MeV/c2 in the neutron-rich nuclear medium at a density of p = (0.057-0.057+0.085) fm-3. Our data are consistent with the Δ self energy determined from measurements of π0 photoproduction from 4He and heavier nuclei.
Original language | English |
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Pages (from-to) | 67-73 |
Number of pages | 7 |
Journal | Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics |
Volume | 530 |
Issue number | 1-4 |
DOIs | |
Publication status | Published - 2002 Mar 28 |
Externally published | Yes |
Keywords
- Delta resonance region
- Few-body system
- He
- Longitudinal-transverse separation
- Medium effects
- Pion electroproduction
- Self energy
ASJC Scopus subject areas
- Nuclear and High Energy Physics