Abstract
The helicity-dependent recoil proton polarizations and as well as the helicity-independent component have been measured in the reaction at four-momentum transfer , center-of-mass proton emission angle , and invariant mass . This first precise measurement of double-polarization observables in the energy domain of the Roper resonance by exploiting recoil polarimetry has allowed for the extraction of its scalar electroexcitation amplitude at an unprecedentedly low value of , establishing a powerful instrument for probing the interplay of quark and meson degrees of freedom in the nucleon.
- Received 15 March 2017
DOI:https://doi.org/10.1103/PhysRevLett.119.022001
© 2017 American Physical Society