Determination of the Strange Form Factors of the Nucleon fromνp,ν¯p, and Parity-Violatinge→

Abstract

Determination of the strange form factors of the nucleon from νp,νp, and parity-violating ep elastic scattering A new method of obtaining the strange form factors of the nucleon is presented, in which forwardangle parity-violating ep elastic scattering data is combined with νp andνp 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 andνp data allows the extraction of all three strange form factors: electric, magnetic and axial (G s E , G s M , and G s A ). In this letter, νp and νp 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 Q 2 = 0.5 GeV 2 . 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 Q 2 of 0.45-1.05 GeV 2 . Measurement of G s A is crucial to the determination of the strange quark contribution to the nucleon spin, ∆s.

Neutral current neutrino-nucleus interactions at intermediate energies

“…Former attempts to extract the strange axial form factor from the data [41,42] faced the fact that, as pointed out by Alberico et al [42], "the experimental uncertainty is still too large to be conclusive about specific values of the strange form factors of the nucleon" and a "rather wide range of values for the strange parameters is compatible with the BNL E734 data." The advent of new polarized electron scattering data from the above mentioned experiments changes appreciably the situation because, as shown by Pate [43,44], it allows to perform a simultaneous determination of all (electric, magnetic and axial) strange form factors with small error bars, in spite of the uncertainties of the E734 data [45]. But this is only possible in the region of 0.45 < Q 2 < 1.05 GeV 2 where the E734 differential cross sections were measured, so new NC neutrino scattering data at low Q 2 are needed for a reliable extrapolation down to Q 2 = 0.…”

A letter of intent for a neutrino scattering experiment on the booster neutrino meanline: FINeSSE

“…This re-analysis uses these three combinations of data to determine all three strange form factors. This results in two possible solutions at Q2 = 0.5 Gey2 summarized in Table 2.2 where Solution 1 is favored [29]. At the present time, there is only sufficient data at Q2 = 0.5 Gey2 to make such a determination.…”

“…A new analysis of the BNL 734 data by Pate [29] combines low energy uN data and parity violating eN elastic scattering data from HAPPEX [30]. Using the known values for the electric, magnetic, and non-strange (CC) axial form factors of the proton and neutron, the difference of the up and Lip elastic cross sections is shown to be a function only of the strange magnetic and axial form factors, C M and CA.…”

The G0 experiment at Jefferson Laboratory: The nucleon strangeness form factors

“…Details of the analysis including final estimates of systematic uncertainties can be found in references [13,12]. Finally, experimental asymmetries have been obtained for 18 Reference [14] has demonstrated that elastic νp andνp cross-sections measurements and PV ep elastic asymmetries can be combined to extract G …”