2003/10/27 by Stephen F. Pate
Physics and Astronomy · #hep-ex #nucl-ex
paper · pdf · doi:10.1103/physrevlett.92.082002
published as Phys.Rev.Lett. 92 (2004) 082002 · 4 pages, 3 figures, 2 tables; to be submitted to Physical Review Letters
arxiv created 2003/10/27 · arxiv updated 2009/12/01
A new method of obtaining the strange form factors of the nucleon is presented, in which forward-angle parity-violating ep elastic scattering data is combined with νp and ν p elastic scattering data. The axial form factor in electron-nucleon scattering is complicated by the presence of electro-weak radiative corrections that in principle need to be calculated or separately measured, but this axial form factor is suppressed at forward angles. The neutrino data has no such complication. Hence the use of forward-angle parity-violating ep data with νp and ν p data allows the extraction of all three strange form factors: electric, magnetic and axial (GEs, GMs, and GAs). In this letter, νp and ν p data from the Brookhaven E734 experiment are combined with the Jefferson Lab HAPPEX ep data to obtain two distinct solutions for the strange form factors at Q2 = 0.5 GeV2. More generally, combining the neutrino elastic scattering data from E734 with the existing and upcoming ep data will yield the strange form factors of the nucleon for Q2 of 0.45-1.05 GeV2. Measurement of GAs is crucial to the determination of the strange quark contribution to the nucleon spin, Δs.