The strange quark contribution to the vector and axial form factors of the nucleon has been determined for momentum transfers in the range 0.45 < Q 2 < 1.0 GeV 2. The results are obtained via a combined analysis of forward-scattering, parity-violating elastic ep asymmetry data from the G0 and HAPPEx experiments at Jefferson Lab, and elastic νp and ¯νp scattering data from Experiment 734 at Brookhaven National Laboratory. The parity-violating asymmetries measured in elastic ep scattering at forward angles establish a relationship between the strange vector form factors Gs E and GsM, with little sensitivity to the strange axial form factor GsA. On the other hand, elastic neutrino scattering at low Q 2 is dominated by the axial form factor, with some significant sensitivity to the vector form factors as well. Combination of the two data sets allows the simultaneous extraction of G s E, Gs M, and Gs A over a significant range of Q2 for the very first time. The Q 2-dependence of the strange axial form factor suggests that the strange quark contribution to the proton spin, ∆s, is negative. PACS numbers: 13.40.Gp,14.20.D
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