Isospin mixing in the nucleon and He-4 and the nucleon strange electric form factor

Conference · Mon Oct 01 04:00:00 EDT 2007

OSTI ID:1963782

Viviani, Michele ^[1]; Schiavilla, Rocco ^[2]

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1. INFN, Sezione di Pisa (Italy)
2. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States)

In order to isolate the contribution of the nucleon strange electric form factor to the parity-violating asymmetry measured in 4He(pol-e, e')He-4 experiments, it is crucial to have a reliable estimate of the magnitude of isospin-symmetry-breaking (ISB) corrections in both the nucleon and He-4. Isospin admixtures in the nucleon are studied by B. Kubis and R. Lewis in Ref. Phys. Rev. C 74, 015204 (2006) in chiral perturbation theory. We examine in the present contribution the issue of isospin admixtures in He-4 derived from ISB components in the nuclear and electromagnetic interactions. 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.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1963782
• Report Number(s): JLAB-THY-07-802; DOE/OR/23177-5884
• Country of Publication: United States
• Language: English