Isospin Mixing in the Nucleon and {sup 4}He and the Nucleon Strange Electric Form Factor
- INFN, Sezione di Pisa, and Department of Physics, University of Pisa, I-56127 Pisa (Italy)
- Jefferson Lab, Newport News, Virginia 23606 (United States)
- HISKP (Theorie), Universitaet Bonn, Nussallee 14-16, D-53115 Bonn (Germany)
- Department of Physics, University of Regina, Regina, Saskatchewan, S4S 0A2 (Canada)
In order to isolate the contribution of the nucleon strange electric form factor to the parity-violating asymmetry measured in {sup 4}He(e-vector,e{sup '}){sup 4}He experiments, it is crucial to have a reliable estimate of the magnitude of isospin-symmetry-breaking (ISB) corrections in both the nucleon and {sup 4}He. We examine this issue in the present Letter. Isospin admixtures in the nucleon are determined in chiral perturbation theory, while those in {sup 4}He are derived from nuclear interactions, including explicit ISB terms. A careful analysis of the model dependence in the resulting predictions for the nucleon and nuclear ISB contributions to the asymmetry is carried out. We conclude that, at the low momentum transfers of interest in recent measurements reported by the HAPPEX Collaboration at Jefferson Lab, these contributions are of comparable magnitude to those associated with strangeness components in the nucleon electric form factor.
- OSTI ID:
- 21028209
- Journal Information:
- Physical Review Letters, Vol. 99, Issue 11; Other Information: DOI: 10.1103/PhysRevLett.99.112002; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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