Electroweak radiative corrections to parity-violating electroexcitation of the Δ
We analyze the degree to which parity-violating (PV) electroexcitation of the Δ(1232) resonance may be used to extract the weak neutral axial vector transition form factors. We find that the axial vector electroweak radiative corrections are large and theoretically uncertain, thereby modifying the nominal interpretation of the PV asymmetry in terms of the weak neutral form factors. We also show that, in contrast with the situation for elastic electron scattering, the axial N→Δ PV asymmetry does not vanish at the photon point as a consequence of a new term entering the radiative corrections. We argue that an experimental determination of these radiative corrections would be of interest for hadron structure theory, possibly shedding light on the violation of Hara's theorem in weak, radiative hyperon decays.
Additional Information© 2001 The American Physical Society Received 10 July 2001; published 20 December 2001 This work was supported in part under U.S. Department of Energy contracts #DE-AC05-84ER40150 and #DEFGO2-00ER41146, the National Science Foundation under Grant No. PHY98-01875, and the National Science Foundation Young Investigator program. C.M.M. acknowledges financial support from FAPESP (Brazil) through grant 99/00080-5. We thank K. Gustafson, T. Ito, J. Martin, R. McKeown, and S. P. Wells for helpful discussions.
Published - ZHUprd02c.pdf