Constraints on axial two-body currents from solar neutrino data

We briefly review recent calculations of neutrino-deuteron cross sections within the effective field theory and traditional potential model approaches. We summarize recent efforts to determine the counter term describing axial two-body currents, L_1A, in the effective field theory approach. We determine the counterterm directly from the solar neutrino data and find several, slightly different, ranges of L_1A under different sets of assumptions. Our most conservative fit value with the largest uncertainty is L_1A=4.5₋₁₂⁺¹⁸ fm³. We show that the contribution of the uncertainty of L_1A to the analysis and interpretation of the solar neutrino data measured at the Sudbury Neutrino Observatory is significantly less than the uncertainty coming from the lack of having a better knowledge of θ₁₃.